Applied Sciences

Editorial

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5 pages, 186 KiB

Open AccessEditorial

Emerging Construction Materials and Sustainable Infrastructure

by Gangbing Song, Yu Zheng and Bo Wu

Appl. Sci. 2019, 9(19), 4127; https://doi.org/10.3390/app9194127 - 2 Oct 2019

Cited by 3 | Viewed by 2044

Abstract

As well reported, ordinary Portland cement (OPC) production causes between 0 [...] Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

Research

Jump to: Editorial

23 pages, 4897 KiB

Open AccessArticle

Research on Application of Uplift-Restricted Slip-Permitted (URSP) Connectors in Steel-Concrete Composite Frames

by Linli Duan, Xin Nie, Ran Ding and Liangdong Zhuang

Appl. Sci. 2019, 9(11), 2235; https://doi.org/10.3390/app9112235 - 30 May 2019

Cited by 23 | Viewed by 4506

Abstract

Tensile stresses and cracks in concrete slabs induced by a hogging moment have always been a disadvantage of steel-concrete composite structures and key issue of concern in the design of such structures. To reduce the tensile stress and control the crack width of [...] Read more.

Tensile stresses and cracks in concrete slabs induced by a hogging moment have always been a disadvantage of steel-concrete composite structures and key issue of concern in the design of such structures. To reduce the tensile stress and control the crack width of the reinforced concrete (RC) slab, a new type of connector, called the uplift-restricted and slip-permitted (URSP) connector has been proposed and successfully applied in the area subjected to a negative bending moment in steel-concrete composite bridges. The feasibility of the URSP connector in steel-concrete composite frame buildings is investigated in this study based on a comprehensive parametric analysis. The effects of URSP connectors on the cracking behavior, as well as the stiffness and strength of composite frames, are systematically analyzed using an elaborate finite element model, which resembles a typical composite beam-column joint subjected to both lateral loads and vertical loads. In addition, an optimized arrangement length of URSP connectors is proposed for practical design. The research findings indicate that the application of URSP connectors greatly improves the crack resistance of RC slabs without an obvious reduction of the ultimate capacity and lateral stiffness of the composite frame. It is recommended that the distribution length of URSP connectors at each beam end should be 20–25% of the frame beam length. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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10 pages, 1031 KiB

Open AccessArticle

Sustainable Silicon Waste Material Utilization for Road Construction: An Application of Modified Binder for Marshall Stability Analysis

by Muhammad Hasnain Saeed, Syyed Adnan Raheel Shah, Hunain Arshad, Ahsan Waqar, Mansoor Abdul Hamid Imam, Abdullah Naveed Sadiq, Salman Hafeez, Junaid Mansoor and Muhammad Waseem

Appl. Sci. 2019, 9(9), 1803; https://doi.org/10.3390/app9091803 - 30 Apr 2019

Cited by 10 | Viewed by 3978

Abstract

Across the globe, sustainable infrastructure development—in context of road networks, and recycling waste material and production—are the two predominant factors associated with the construction industry in making roads and developing transportation networks. Globally, millions of tons of basic hot mix asphalt are produced, [...] Read more.

Across the globe, sustainable infrastructure development—in context of road networks, and recycling waste material and production—are the two predominant factors associated with the construction industry in making roads and developing transportation networks. Globally, millions of tons of basic hot mix asphalt are produced, which are being utilized to generate large volumes of the finished road material. This study deals with the method of modifying bitumen by adding a silicon mobile cover waste material in a cost-effective manner, that can yield improved characteristic properties to bitumen, in a sustainable way to save material, improve quality/performance and reduce costs. In this investigation, globally produced and used mobile silicon cover accessories were utilized as a partial replacement (at 10%, 20%, 30%, 40%, and 50%) with bitumen. A large quantity of used silicon phone covers are thrown in the garbage and dumped in grounds as a waste material worldwide. Modifying bitumen with up to 40% silicon, using a potentially viable waste available in large quantities, was proven to be stabilized according to ASTM Marshall Test criteria of stability (>9) and flow(within range 2–4) in road construction. The results of the investigation are promising, and the use of silicon waste could mark a significant impact on the economics of road construction industry for sustainable infrastructure development by saving bitumen, which is a costly resource. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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21 pages, 9031 KiB

Open AccessArticle

Application of Polymer Curing Agent in Ecological Protection Engineering of Weak Rock Slopes

by Ding Yao, Guoping Qian, Jiawu Liu and Jialiang Yao

Appl. Sci. 2019, 9(8), 1585; https://doi.org/10.3390/app9081585 - 17 Apr 2019

Cited by 12 | Viewed by 3722

Abstract

Under the action of water, weak rock slopes easily expand and the strength and stiffness decrease, which results in slope instability. The styrene–acrylic emulsion cement-matrix composite, a new type of polymer curing agent, was developed for the curing and treatment of weak rock [...] Read more.

Under the action of water, weak rock slopes easily expand and the strength and stiffness decrease, which results in slope instability. The styrene–acrylic emulsion cement-matrix composite, a new type of polymer curing agent, was developed for the curing and treatment of weak rock slopes. The strength-reduction factor method and ANSYS finite element software were used to calculate and analyze the stability of slopes before and after protection. The stability safety factor of weak rock after protection increased by 30% from 2.0 to 2.6. In order to evaluate the performance of the polymer curing agent, the mixture test was carried out in the laboratory. It was found that the waterproofness, hydrophobicity, and microstructure of weak rock slopes with the polymer curing agent can be significantly improved. Finally, the polymer curing agent was adopted and the external-soil spray-seeding technique was used in physical engineering. From test results, it was indicated that the polymer curing agent for weak slopes is beneficial in improving the water-damage resistance of a slope surface and prevent or reduce the softening of weak rock so that plants can grow for a long time. The treatment for weak rock slopes was successfully combined with plant protection, achieving the dual effect of weak rock slope protection and ecological protection. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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18 pages, 5297 KiB

Open AccessArticle

Experimental Research on Bond Behavior between GFRP Bars and Stirrups-Confined Concrete

by Kui Gao, Zhao Li, Jiarui Zhang, Jianwei Tu and Xinping Li

Appl. Sci. 2019, 9(7), 1340; https://doi.org/10.3390/app9071340 - 29 Mar 2019

Cited by 19 | Viewed by 4420

Abstract

This paper presents the results of a series of pullout tests that were performed on Glass-fiber-reinforced polymer (GFRP) bars embedded in concrete, while providing a detailed report on the influence of various variables that impinge upon bond behavior, such as the surface characteristics [...] Read more.

This paper presents the results of a series of pullout tests that were performed on Glass-fiber-reinforced polymer (GFRP) bars embedded in concrete, while providing a detailed report on the influence of various variables that impinge upon bond behavior, such as the surface characteristics and diameter of the bars, concrete strength, as well as the confined effect of stirrups. The Bertero-Popov-Eligehausen (BPE) and Cosenza-Manfredi-Realfonzo (CMR) models analyzed the bond stress (τ)–slip (s) relationship between GFRP bar and stirrups-confined concrete. The tests results indicate that when the bond failure interface only occurs on the surface of a GFRP bar, the bond strength is not dependent upon the concrete strength. Moreover, the results indicate that in comparison to specimens without stirrups, their stirrup-containing counterparts are more prone to pullout failure with greater ductility and higher bond strength and corresponding slip. The BPE and CMR models are able to investigate the τ-s relationship between GFRP bars and the stirrups-confined concrete with accuracy. With the experimental data, the specific parameters in the models classified by surface characteristics have been suggested. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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10 pages, 4048 KiB

Open AccessArticle

Strength and Water Purification Properties of Environment-Friendly Construction Material Produced with the (D)PAOs and Zeolite

by Young-Il Jang, Byung-Jae Lee and Jong-Won Lee

Appl. Sci. 2019, 9(5), 972; https://doi.org/10.3390/app9050972 - 7 Mar 2019

Cited by 7 | Viewed by 2759

Abstract

The goal of this study was to improve the water purification performance of secondary concrete products that can be used in rivers and streams. To this end, mortar and porous concrete were produced by adding both de-nitrifying phosphate accumulating organisms ((D)PAOs) and zeolite, [...] Read more.

The goal of this study was to improve the water purification performance of secondary concrete products that can be used in rivers and streams. To this end, mortar and porous concrete were produced by adding both de-nitrifying phosphate accumulating organisms ((D)PAOs) and zeolite, and their mechanical properties and water purification performance were analyzed. The compression strength test results showed that the strength was the highest when the mixing ratios of (D)PAOs and zeolite were set to 10% and 5%, respectively. For better contaminant adsorption, however, the optimal mixing ratio of zeolite was determined to be 10%. When the mixing ratio of (D)PAOs was set to 10%, the concentrations of biochemical oxygen demand (BOD) and chemical oxygen demand (COD) decreased by 57.9% and 89.9%, respectively, after seven days of immersion when compared to the initial concentrations. When compared to plain porous concrete, the total nitrogen (T-N) and total phosphorus (T-P) removal ratios of the develop concrete were 11.0% and 17.8% higher, respectively. When the mixing ratios of (D)PAOs and zeolite were set to 10% for both, the T-N and T-P removal ratios were determined to be 86.3% and 88.1%, respectively, while the BOD and COD concentrations were 2.668 mg/L and 16.915 mg/L, respectively. In simpler terms, the water purification performance was up to 17% higher in the concrete mixed with both 10% (D)PAOs and 10% zeolite than in the concrete mixed with 10% (D)PAOs only. Overall, the optimal mixing ratios of (D)PAOs and zeolite to maximize the water purification effect of secondary concrete products while maintaining their strengths equivalent to or higher than those of their corresponding plain concrete products are considered to be 10% for both. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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16 pages, 10153 KiB

Open AccessArticle

Experimental Investigation of the Natural Bonding Strength between Stay-In-Place Form and Concrete in FRP-Concrete Decks/Beams

by Jianwu Gong, Xingxing Zou and Ping Xia

Appl. Sci. 2019, 9(5), 913; https://doi.org/10.3390/app9050913 - 4 Mar 2019

Cited by 12 | Viewed by 3943

Abstract

The Fiber Reinforced Polymer (FRP)-concrete hybrid deck/beam is a structural system that combines the durable thin-walled FRP composite profiles and the cost-effective concrete by interfacial shear connections. The interfacial slip can reduce the composite action, thereby causing a degradation of flexural rigidity and [...] Read more.

The Fiber Reinforced Polymer (FRP)-concrete hybrid deck/beam is a structural system that combines the durable thin-walled FRP composite profiles and the cost-effective concrete by interfacial shear connections. The interfacial slip can reduce the composite action, thereby causing a degradation of flexural rigidity and capacity. Therefore, using stay-in-place (SIP) forms is a simple way to fully utilize the natural bonding between FRP and concrete, which plays a pivotal role in the structural design of FRP-concrete hybrid decks/beams. This paper presents an experimental study on the natural bonding provided by the SIP forms and the in situ cast concrete. First, four comparative push-out test specimens revealed that the use of SIP forms could improve the ultimate shear capacity of steel bolts by 11.1%. Moreover, it could provide an initial stage with nearly zero slip. The average natural bonding strength of FRP-concrete was evaluated as 0.27 MPa, which agreed well with previous tests in the literature. Second, the beam specimen also confirmed that there was a load response stage with nearly zero slip along the FRP-concrete interface when SIP forms were used as the permanent form. Third, the strain measurements on the steel bolts, FRP profile, and concrete revealed that the failure of the natural bonding was a brittle process. Finally, the flexural response of the FRP-concrete hybrid beam was analytically modeled as three distinct stages, namely the full composite action stage, the slipping stage caused by a natural bonding decrease, and the partial composite action stage. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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17 pages, 5191 KiB

Open AccessArticle

Experimental Study of the Mechanical Behavior of the Steel–Concrete Joints in a Composite Truss Bridge

by Yingliang Tan, Bing Zhu, Tingyi Yan, Biao Huang, Xuewei Wang, Wenwei Yang and Bo Huang

Appl. Sci. 2019, 9(5), 854; https://doi.org/10.3390/app9050854 - 27 Feb 2019

Cited by 14 | Viewed by 3944

Abstract

The mechanical behavior of the steel–concrete joints in a composite bridge was investigated. Pull-out tests on eight specimens were carried out to evaluate the connection performance of Perfobond rib shear connectors (PBL shear connectors). In addition, static load tests were conducted on three [...] Read more.

The mechanical behavior of the steel–concrete joints in a composite bridge was investigated. Pull-out tests on eight specimens were carried out to evaluate the connection performance of Perfobond rib shear connectors (PBL shear connectors). In addition, static load tests were conducted on three composite joint specimens with a scale of 1/2 in a composite truss bridge. The crack load, load–displacement curves, strain distribution, and the joint stiffness were obtained from the composite joint to analyze the mechanical behavior of steel–concrete joints. The experimental results show that the embedded depth plays an important role in the ultimate bearing capacity and the deformation of PBL shear connectors and could even change the failure mode. Based on the test results of composite joints, the displacement increased almost linearly with the horizontal load on the concrete chord. There was no evident failure, and large deformation occurred in composite joints. In addition, the ultimate loads obtained from three composite joint specimens were greater than 2.93 times the design load (2050 kN). These investigated composite joints had excellent bearing capacity (above 6000 kN). This study will provide an experimental reference for the design of steel–concrete joints for composite truss bridges. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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20 pages, 12557 KiB

Open AccessArticle

Experimental and Parametric Study on the Pull-Out Resistance of a Notched Perfobond Shear Connector

by Shuangjie Zheng, Yuqing Liu, Yangqing Liu and Chen Zhao

Appl. Sci. 2019, 9(4), 764; https://doi.org/10.3390/app9040764 - 21 Feb 2019

Cited by 16 | Viewed by 4258

Abstract

To ease the installation of perforating rebars through multi-holes, an alternative notched perfobond shear connector was proposed by cutting out the hole edge. This paper presents the test results of six pull-out specimens with conventional and notched perfobond shear connectors. The objective was [...] Read more.

To ease the installation of perforating rebars through multi-holes, an alternative notched perfobond shear connector was proposed by cutting out the hole edge. This paper presents the test results of six pull-out specimens with conventional and notched perfobond shear connectors. The objective was to compare the failure modes and pull-out behaviors of perfobond shear connectors using circular holes and notched holes. Furthermore, the explicit finite element method was introduced and validated to generate parametric results for pull-out tests of notched perfobond shear connectors. A total of 33 parametric simulations were performed to further study the influences of several variables, including the hole diameter, the cut width, the perfobond thickness, the concrete strength, the diameter and strength of the rebar, and the strength of the structural steel. The experimental and numerical results were used to evaluate the previous equations for perfobond shear connectors. Finally, an alternative equation was proposed to estimate the pull-out resistance of notched perfobond shear connectors. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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13 pages, 2788 KiB

Open AccessArticle

Durability Parameters of Reinforced Recycled Aggregate Concrete: Case Study

by S. P. Arredondo-Rea, R. Corral-Higuera, J. M. Gómez-Soberón, D. C. Gámez-García, J. M. Bernal-Camacho, C. A. Rosas-Casarez and M. J. Ungsson-Nieblas

Appl. Sci. 2019, 9(4), 617; https://doi.org/10.3390/app9040617 - 13 Feb 2019

Cited by 42 | Viewed by 4422

Abstract

Recycled concrete aggregate (RA) from pavement demolition was used to make concrete. Ten concrete mixtures with different replacement percentages of RA (coarse and fine) were made. The corrosion rate of steel and the electrical resistivity of concrete were determined on reinforced concrete specimens [...] Read more.

Recycled concrete aggregate (RA) from pavement demolition was used to make concrete. Ten concrete mixtures with different replacement percentages of RA (coarse and fine) were made. The corrosion rate of steel and the electrical resistivity of concrete were determined on reinforced concrete specimens subjected to wetting-drying cycles (3.5% solution of NaCl). Corrosion rate was determined using the electrochemical technique of linear polarization resistance, while the electrical resistivity was measured by electrochemical impedance spectroscopy. The results show that the use of RA introduces more interfaces in concrete, which accelerates the steel corrosion process because the porosity increases and the electrical resistivity decreases. However, steel corrosion and the electrical resistivity in concrete are not significantly influenced by replacing a maximum 30% of coarse aggregate or 20% of fine aggregate with RA. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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5 pages, 1684 KiB

Open AccessArticle

Preparation of Carbon Nitride Dots with Sizes Larger than 20 nm

by Peihui Luo, Yunlong Yu and Xiangfeng Guan

Appl. Sci. 2019, 9(3), 464; https://doi.org/10.3390/app9030464 - 29 Jan 2019

Cited by 1 | Viewed by 2971

Abstract

Carbon nitride dots (CNDs) were obtained via carbonization of polymer formed via the reaction of 1, 2-ethylenediamine (EDA) and CCl₄. The average diameter of CNDs is calculated to be ca. 44 nm. They possess solubility in water and polar organic solvents. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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20 pages, 6317 KiB

Open AccessArticle

Damage Analyses of Replaceable Links in Eccentrically Braced Frame (EBF) Subject to Cyclic Loading

by Zhanzhong Yin, Dazhe Feng and Wenwei Yang

Appl. Sci. 2019, 9(2), 332; https://doi.org/10.3390/app9020332 - 18 Jan 2019

Cited by 15 | Viewed by 4653

Abstract

In the current design of steel eccentrically braced frames (EBFs), the yielding link is coupled with the floor beam. This causes the design of cross-sectional dimensions of links to be enlarged, resulting in over-designed structures and foundations, and increasing the cost of the [...] Read more.

In the current design of steel eccentrically braced frames (EBFs), the yielding link is coupled with the floor beam. This causes the design of cross-sectional dimensions of links to be enlarged, resulting in over-designed structures and foundations, and increasing the cost of the overall structure. In addition, the beams are forecast to sustain severe damage through repeated inelastic deformations under design-level earthquakes, and thus the structure may require extensive repair or need to be replaced. To improve upon these drawbacks, a shear device with replaceable links based on EBFs was designed. The hysteresis curve, the stress distribution, and the deformation of the specimen were obtained by cyclic loading tests of the eight replaceable links. The energy dissipation behavior, the bearing capacity, the failure modes, and the plastic rotation angle of those specimens were analyzed. The results indicated clearly that the links in this shear device had inelastic deformation concentrated in the link showing very stable hysteresis behavior, and damaged links were replaced easily as end-plate connections were adopted. The energy dissipation capacity and the plastic rotation angle of the specimens were mainly dependent on the arrangement of stiffener, length ratio, and welding access holes. Experimental studies performed in this research and the related damage analyses reveal that cracks are the major causes of damage to the EBF and there is a lack of research on real-time monitoring of the onset and development of these cracks in EBF structures. As a future work, this paper proposes a piezoceramic patch transducer-based active sensing approach to monitor the crack onset and development of the EBF when subjected to dynamic loadings. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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19 pages, 5378 KiB

Open AccessArticle

Study on Restoring Force Performance of Corrosion Damage Steel Frame Beams under Acid Atmosphere

by Bin Wang, Weizeng Huang and Shansuo Zheng

Appl. Sci. 2019, 9(1), 103; https://doi.org/10.3390/app9010103 - 29 Dec 2018

Cited by 10 | Viewed by 3169

Abstract

In order to study the restoring force characteristics of corroded steel frame beams in an acidic atmosphere, based on different corrosion damage degrees, tests on the material properties of 48 steel samples and six steel frame beam specimens with a scale ratio of [...] Read more.

In order to study the restoring force characteristics of corroded steel frame beams in an acidic atmosphere, based on different corrosion damage degrees, tests on the material properties of 48 steel samples and six steel frame beam specimens with a scale ratio of 1/2 under low cyclic repeated loading were conducted. According to the test results, the relationship between the weight loss rate and the mechanical properties of corrosion damage steel was obtained by numerical regression analysis, and the hysteresis curves and skeleton curves of the corroded steel frame beams were also obtained. The simplified trilinear skeleton curve model of the corroded steel frame beams and the expression of the corresponding feature points were determined by analyzing the failure process. The strength and stiffness degradation rule of the steel frame beam was analyzed furtherly. The hysteresis rule was established by introducing the cyclic degradation index which considers the effect of different corrosion degrees, and finally the restoring force model based on the corroded steel frame beams in an acidic atmospheric environment was established. Comparison with the test results show that the skeleton curve and the restoring force model established in this paper can accurately describe the seismic performance of corrosion damaged steel frame beams and can provide a basis for the seismic calculation analysis of corroded steel structures in an acidic atmosphere. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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18 pages, 3731 KiB

Open AccessArticle

Permeability and Leaching Properties of Recycled Concrete Aggregate as an Emerging Material in Civil Engineering

by Andrzej Głuchowski, Wojciech Sas, Justyna Dzięcioł, Emil Soból and Alojzy Szymański

Appl. Sci. 2019, 9(1), 81; https://doi.org/10.3390/app9010081 - 26 Dec 2018

Cited by 17 | Viewed by 3918

Abstract

In this article, a study of the threshold gradient and leaching properties for recycled material, namely, recycled concrete aggregate (RCA), was conducted. The RCA in this study is a material that comes from recycling concrete debris. A series of tests in permeameter apparatus [...] Read more.

In this article, a study of the threshold gradient and leaching properties for recycled material, namely, recycled concrete aggregate (RCA), was conducted. The RCA in this study is a material that comes from recycling concrete debris. A series of tests in permeameter apparatus in a constant head manner were conducted. The test method has been improved to eliminate common mistakes, which occur when the constant head method is used. During the following study, aggregates with gradations equal to 0–8, 0–16, and 0.05–16 mm were tested. The tests were conducted on gradients ranging from 0.2 to 0.83. This range of tested gradients led to the evaluation of the flux velocity and indicated non-Darcian flow. For engineering applications, the threshold gradients for three RCA blends were calculated using a statistical analysis. The average coefficient of permeability, k_avg, for linear flow was equal to 1.02 × 10⁻⁴–1.89 × 10⁻⁴ m/s. In this paper, suffosion analysis was also conducted for the three blends in order to eliminate the possibility of particle movement. Moreover, for RCA blend 0–16 mm, leaching properties was examined. It was found that the concentration of chlorides, sulphates, and heavy metals in the water solution does not exceed the permissible standards. This paper ends with conclusions and proposals concerning the threshold gradients obtained from the statistical analysis, suffosion analysis, and flux velocity. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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14 pages, 4017 KiB

Open AccessArticle

Effect of Mineral Additives on the Behavior of an Expansive Soil for Use in Highway Subgrade Soils

by Yongzhen Cheng and Xiaoming Huang

Appl. Sci. 2019, 9(1), 30; https://doi.org/10.3390/app9010030 - 22 Dec 2018

Cited by 19 | Viewed by 5186

Abstract

Black cotton soil (BCS) forms a major soil group in Kenya and is characterized by high shrink/swell potential when exposed to water. A comprehensive series of laboratory tests were performed on BCS treated with lime (0–9%), volcanic ash (VA, 0–25%), and their combinations [...] Read more.

Black cotton soil (BCS) forms a major soil group in Kenya and is characterized by high shrink/swell potential when exposed to water. A comprehensive series of laboratory tests were performed on BCS treated with lime (0–9%), volcanic ash (VA, 0–25%), and their combinations in order to study the physical–mechanical properties and mineralogical changes of the stabilized BCS. Moreover, a test road which replaced the BCS with the lime–VA-stabilized BCS was constructed to investigate the moisture change and soil movement in the BCS foundation. The results revealed that BCS stabilized with combinations of lime and VA shows larger California bearing ratio (CBR) and unconfined compressive strength (UCS) values when compared with a single stabilizer. BCS stabilized with 3% lime + 15% VA meets the performance requirements of roadbed materials in accordance with JTG D30-2015. The increase of pH and electrical conductivity (EC) in the stabilized soil promotes chemical reactions between the stabilizers and BCS to form new cementing agents, which are confirmed by X-ray diffraction (XRD) and transmission electron microscope (TEM) findings. The replacement of BCS with 3% lime + 15% VA-stabilized BCS shows an obvious effect on controlling the moisture change and soil movement in the foundation BCS. This research provides a low-cost strategy for making use of the vast resources of BCS in Kenya obtained from foundation excavation. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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16 pages, 12023 KiB

Open AccessArticle

Compaction Characteristics and Minimum Void Ratio Prediction Model for Gap-Graded Soil-Rock Mixture

by Tao Wang, Sihong Liu, Yan Feng and Jidu Yu

Appl. Sci. 2018, 8(12), 2584; https://doi.org/10.3390/app8122584 - 12 Dec 2018

Cited by 10 | Viewed by 5837

Abstract

Gap-graded soil-rock mixtures (SRMs), composed of coarse-grained rocks and fine-grained soils particles, are very inhomogeneous materials and widely encountered in geoengineering. In geoengineering applications, it is necessary to know the compaction characteristics in order to estimate the minimum void ratio of gap-graded SRMs. [...] Read more.

Gap-graded soil-rock mixtures (SRMs), composed of coarse-grained rocks and fine-grained soils particles, are very inhomogeneous materials and widely encountered in geoengineering. In geoengineering applications, it is necessary to know the compaction characteristics in order to estimate the minimum void ratio of gap-graded SRMs. In this paper, the void ratios of compacted SRMs as well as the particle breakage during vibrating compaction were investigated through a series of vibrating compaction tests. The test results show that gap-graded SRMs may reach a smaller void ratio than the SRM with a continuous gradation under some circumstances. When the particles in a gap interval play the role of filling components, the absence of them will increase the void ratio of the SRM. The particle breakage of gap-graded SRMs is more prominent than the SRM with continuous gradation on the whole, especially at the gap interval of 5–20 mm. Based on the test results, a minimum void ratio prediction model incorporating particle breakage during compaction is proposed. The developed model is evaluated by the compaction test results and its validation is discussed. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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22 pages, 5319 KiB

Open AccessArticle

Experimental Study on the Static Behavior of Reinforced Warren Circular Hollow Section (CHS) Tubular Trusses

by Wenwei Yang, Jiankang Lin, Ni-na Gao and Ruhao Yan

Appl. Sci. 2018, 8(11), 2237; https://doi.org/10.3390/app8112237 - 13 Nov 2018

Cited by 13 | Viewed by 14786

Abstract

For truss structures, the question of whether to weld hidden welds or not has been controversial. In the actual construction process of truss structures, the members are usually spot welded in place on the assembly platform, and then welded as a whole, while [...] Read more.

For truss structures, the question of whether to weld hidden welds or not has been controversial. In the actual construction process of truss structures, the members are usually spot welded in place on the assembly platform, and then welded as a whole, while the hidden welds of the truss are not welded, especially for small pipe diameter trusses. Furthermore, in this study, under hidden weld unwelded conditions, two kinds of reinforcing method (adding a half outer sleeve on each joint and filling concrete into the chord members) are adopted to achieve the purpose of strengthening the truss. Therefore, this paper presents an experimental study on the static behavior of four types of Warren tubular trusses made of CHS members. These four types are (1) T-HW: The truss with hidden welds welded; (2) T-HN: The truss with hidden welds unwelded; (3) TS-AS: The truss strengthened on the basis of T-HN by adding a half outer sleeve on each joint; (4) TS-FC: The truss strengthened on the basis of T-HN by filling concrete into the top and bottom chord members. The mechanical behavior, failure mode, bearing capacity, and load-displacement of all specimens were investigated. The surface plasticity of the bottom chord member, the weld fracture around tubular joints at the bottom chord member, and the bending deformation of the bottom chord member were observed in the tests. Compared with the T-HW specimen, the load carrying capacity of the T-HN specimen decreased by 18%. On the other hand, the T-HN specimen has better deformability than the T-HW specimen. The reinforcing method of adding a half outer sleeve on each joint and filling concrete into the chord members can effectively improve the load carrying capacity and stiffness of the truss, thus reducing the overall deformation of the truss, but the reinforcing method of filling concrete into the chord members is more efficient. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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22 pages, 11504 KiB

Open AccessArticle

Hybrid Fibres as Shear Reinforcement in High-Performance Concrete Beams with and without Openings

by Piotr Smarzewski

Appl. Sci. 2018, 8(11), 2070; https://doi.org/10.3390/app8112070 - 26 Oct 2018

Cited by 35 | Viewed by 3785

Abstract

The article presents the results of research work aimed at testing the use of hybrid steel-polypropylene fibre as a strengthening solution to upgrade reinforced high-performance concrete (HPC) beams with openings (BO1 ÷ BO3) and without (B1 ÷ B3). A total of six simply [...] Read more.

The article presents the results of research work aimed at testing the use of hybrid steel-polypropylene fibre as a strengthening solution to upgrade reinforced high-performance concrete (HPC) beams with openings (BO1 ÷ BO3) and without (B1 ÷ B3). A total of six simply supported beams were tested under four-point bending. The test beams had a cross section of 200 × 400 mm and a total length of 2500 mm. Two square openings in each shear span were located symmetrically about the mid-point in three BO beams. Research was carried out with regard to the quantity and type of reinforcement. Beams B1 and BO1 were constructed with traditional reinforcement made of steel bars. As regards the remaining beams, instead of stirrups and compressive bars, fibre reinforcement of varying fibre volume contents was applied. In the analysis, a non-contact system for three-dimensional measurements of strain and displacement was used. Analysis of the behaviour of the beams under static load was based on the measurements of cracks, deflections and strains. The test results show that the first diagonal crack and the ultimate shear strength increase significantly as the fibre content increases. The above study showed that the hybrid fibres have a positive effect, reducing crack width and ensuring an increase in the load-bearing capacity. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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20 pages, 9084 KiB

Open AccessArticle

3D Numerical Analysis of Synergetic Interaction between High-Rise Building Basement and CFG Piles Foundation

by Xirong Niu, Yangping Yao, Yanfang Sun, Yuhao He and Haiqing Zhang

Appl. Sci. 2018, 8(11), 2040; https://doi.org/10.3390/app8112040 - 24 Oct 2018

Cited by 7 | Viewed by 5543

Abstract

A strong bearing capacity and the satisfaction of strict settlement requirements are necessary for high-rise buildings. A single-raft foundation cannot meet certain settlement requirements, in which case CFG (cement/fly ash/gravel, an emerging and sustainable construction material) piles can be used in the foundation [...] Read more.

A strong bearing capacity and the satisfaction of strict settlement requirements are necessary for high-rise buildings. A single-raft foundation cannot meet certain settlement requirements, in which case CFG (cement/fly ash/gravel, an emerging and sustainable construction material) piles can be used in the foundation to set up a cushion between the top of the pile and the raft slab, where the piles act as settlement reducers. The rafts of disconnected piles (DPs) exhibit complex synergetic interactions involving the raft, cushion, pile, and soil under the load of the superstructure. Multiple piles in particular lead to an increase in the number of degrees of freedom of the problem, resulting in difficulty in solving it. However, when the number of piles is very large and the structure is complex—for example, many buildings are placed on the same raft with basement structures—even if the embedded pile element is used during numerical calculations, either the method remains prone to non-convergence or the time needed for numerical calculations is too long. It is, thus, difficult to satisfy the requirement of an efficient scheme of evaluation in practice. To solve this problem, a method that uses a simulation of the integral equivalent of the CFG pile reinforcement zone is proposed in this paper. In the CFG pile reinforcement zone, the effect of the pile is reflected in the enhancement of parameters of the soil in the strengthened zone, and the reinforcement zone (including the soil and the pile) is regarded as an anisotropic elastoplastic material. As the structure of the pile is no longer needed in the model, its elimination significantly reduces the complexity of the model and improves its calculation efficiency. An example of a numerical calculation is provided to verify the viability and accuracy of the integral equivalent simulation method in comparison with the embedded pile element simulation method. Finally, the proposed method is applied to the three-dimensional numerical analysis of a scheme for the treatment of foundations of high- and low-rise buildings with basements, and its effectiveness is further verified through comparison with theoretical results. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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15 pages, 2698 KiB

Open AccessArticle

Numerical Investigation of the Nonlinear Composite Action of FRP-Concrete Hybrid Beams/Decks

by Jianwu Gong, Xingxing Zou, Han Shi, Cheng Jiang and Zhaochao Li

Appl. Sci. 2018, 8(11), 2031; https://doi.org/10.3390/app8112031 - 23 Oct 2018

Cited by 6 | Viewed by 2744

Abstract

Interfacial slip can cause rigidity degradation and stress concentration in fiber-reinforced polymer-concrete hybrid beam (FCHB). Therefore, precisely evaluating the composite action between fiber-reinforced polymer (FRP) and concrete of FCHB plays a pivotal role in structural analysis and design. Previous push-out tests showed that [...] Read more.

Interfacial slip can cause rigidity degradation and stress concentration in fiber-reinforced polymer-concrete hybrid beam (FCHB). Therefore, precisely evaluating the composite action between fiber-reinforced polymer (FRP) and concrete of FCHB plays a pivotal role in structural analysis and design. Previous push-out tests showed that most connections for FCHB behave nonlinearly in load-slip relationships even at a low load level. However, existing analytical equations have their limitations due to the assumption of linear load-slip interfacial relationship which is not suitable for FCHB. The originality of this paper is to propose a finite difference method (FDM) to elaborate the interfacial slip and shear stress. FDM agreed well with the analytical solutions of the linear load-slip relationships for connections. Results indicate that higher accurateness can be obtained by using more elements. And 40 elements for half span of FCHB can reduce the error of numerical results to 1%. Then, the proposed FDM was expanded to predict the interfacial behavior of FCHB considering nonlinear interfacial load-slip relationships. It was found that perforated FRP rib connections can ensure nearly full composite action and the bolted connection can lead to a very high slip level. The use of ultra-high performance concrete (UHPC) results in a higher degree of composite action than normal concrete. The deflection considering slip was computed by adding deformation under full composition action and that caused by the slip effect. It was suggested that high strength steel bolts are effective both in normal concrete and UHPC. When the slip modulus is suggested to be larger than 20 kN/mm, the capacity per bolt should be larger than 20 kN. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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19 pages, 12934 KiB

Open AccessArticle

Experimental and Numerical Study on the Seismic Performance of Prefabricated Reinforced Masonry Shear Walls

by Weifan Xu, Xu Yang, Fenglai Wang and Bin Chi

Appl. Sci. 2018, 8(10), 1856; https://doi.org/10.3390/app8101856 - 9 Oct 2018

Cited by 16 | Viewed by 4103

Abstract

The seismic performance of prefabricated reinforced concrete block masonry shear walls (PRMSWs) was studied. Five PRMSWs were tested under cyclic loading to evaluate the effect of the axial compression ratio and the distribution of the vertical rebar on the inelastic behavior. Based on [...] Read more.

The seismic performance of prefabricated reinforced concrete block masonry shear walls (PRMSWs) was studied. Five PRMSWs were tested under cyclic loading to evaluate the effect of the axial compression ratio and the distribution of the vertical rebar on the inelastic behavior. Based on the experimental results, the lateral load capacity, failure mode, lateral drift, ductility, stiffness degradation, energy dissipation, and the seismic performance stability of the specimens were analyzed. The finite element analysis of the specimens was conducted with ABAQUS, which agreed quite well with the laboratory findings. Relevant results showed that PRMSW exhibited favorable ductility and energy dissipation. The increase of the compression ratio led to stiffer, but more brittle, inelastic behavior of the specimens that had higher flexural strength. The shear walls that had concentrated vertical rebar at the sides exhibited relatively higher load capacity and less ductility compared to the walls that had evenly distributed rebar. The inelastic lateral drift limit of the PRMSW could be assigned 1/120. The equivalent viscous damping ratio of the PRMSW was 9–13% at ultimate load. These results provide a technical basis for the design and application of the PRMSW structures. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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20 pages, 4398 KiB

Open AccessFeature PaperArticle

Performance of Concrete with Waste Granite Powder: The Effect of Superplasticizers

by Elyas Asadi Shamsabadi, Mansour Ghalehnovi, Jorge De Brito and Ali Khodabakhshian

Appl. Sci. 2018, 8(10), 1808; https://doi.org/10.3390/app8101808 - 2 Oct 2018

Cited by 58 | Viewed by 7293

Abstract

Granite stone is highly demanded by construction sector. In the processing stage, great amounts of waste powder are produced that can be used as cement replacement in concrete production. Reduced workability is the first problem of this replacement and it can be mitigated [...] Read more.

Granite stone is highly demanded by construction sector. In the processing stage, great amounts of waste powder are produced that can be used as cement replacement in concrete production. Reduced workability is the first problem of this replacement and it can be mitigated by using superplasticizers (SP). This study was carried out to limit the disadvantages related to waste granite powder (WGP) use through the use of SP. For this purpose, 19 concrete mixes containing various types of SP with different contents and WGP as cement replacement were appraised. Fresh concrete density, splitting tensile strength, electrical resistivity, compressive strength and resistance to sulphate attack tests were conducted. The mixes were assessed based on their environmental impact, economic, and mechanical performance. The results have shown that SP can eliminate most disadvantages caused by using stone waste, particularly negative effects on the mechanical properties. They can even improve some properties of concrete, including electrical resistivity by up to around 90%. Furthermore, the concrete mixes PT5, PF5, and PF10, which were made with both SP and stone waste, obtained the best results, with over 30% improvement in the multi-criteria evaluation index values compared to the mix W0 (reference mix). The proper use of WGP as replacement for cement would have environmental benefits and help the economy of the granite stone industry. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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24 pages, 9541 KiB

Open AccessArticle

Study on Hysteresis Model of Welding Material in Unstiffened Welded Joints of Steel Tubular Truss Structure

by Yaqi Suo, Wenwei Yang and Peng Chen

Appl. Sci. 2018, 8(9), 1701; https://doi.org/10.3390/app8091701 - 19 Sep 2018

Cited by 9 | Viewed by 7578

Abstract

The weld form of intersecting joints in a steel tubular truss structure changes with the various intersecting curves. As the key role of joints in energy dissipation and seismic resistance, the weld is easy to damage, as a result the constitutive behavior of [...] Read more.

The weld form of intersecting joints in a steel tubular truss structure changes with the various intersecting curves. As the key role of joints in energy dissipation and seismic resistance, the weld is easy to damage, as a result the constitutive behavior of the weld is different from that of the base metal. In order to define the cumulative damage characteristic and study the constitutive behavior of welded metal with the influence of damage accumulation, low-cycle fatigue tests were carried out to evaluate overall response characteristics and to quantify variation of cyclic stress amplitude, unloading stiffness and energy dissipation capacity. The results show that the cyclic softening behavior of welding materials is apparent, however, the steel shows hardening behavior with the increase of cyclic cycles, while the cyclic stress amplitude, unloading stiffness, and energy dissipation capacity of the welding materials degenerate gradually. Based on the Ramberg–Osgood model and introducing the damage variable D, a hysteretic model of welding material with the effect of damage accumulation was established, including an initial loading curve, cyclic stress-strain curve, and hysteretic curve model. Further, the evolution equation of D was also built. The parameters reflecting the damage degradation were fitted by the test data, and the simulation results of the model were proved to be in good agreement with the test results. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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17 pages, 3535 KiB

Open AccessArticle

Study on Structural Robustness of Isolated Structure Based on Seismic Response

by Wenwei Yang, Chao Bao, Xiaotong Ma and Shangrong Zhang

Appl. Sci. 2018, 8(9), 1686; https://doi.org/10.3390/app8091686 - 18 Sep 2018

Cited by 8 | Viewed by 4188

Abstract

The qualitative analysis for structural robustness study subjected to severe earthquakes is unable to meet engineering requirements, and a quantitative analysis method for structural robustness is needed to be proposed. The existing analysis methods, such as Incremental Dynamic Analysis Method and Pushover method, [...] Read more.

The qualitative analysis for structural robustness study subjected to severe earthquakes is unable to meet engineering requirements, and a quantitative analysis method for structural robustness is needed to be proposed. The existing analysis methods, such as Incremental Dynamic Analysis Method and Pushover method, only study the response of the structure directly from the macroscopic view, rather than focusing on the response of a single component on the structure. Especially for the construction of isolated structure, the impact of accidental bearing failure on the isolated structure and the impact of progressive collapse cannot be considered. In this paper, based on the Alternative Load Path Method, the quantitative analysis method for structural robustness analysis under earthquake is proposed. The structural robustness of some different vertical irregular isolated structures under different earthquakes is studied. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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11 pages, 2816 KiB

Open AccessArticle

Research on Compression Behavior of Square Thin-Walled CFST Columns with Steel-Bar Stiffeners

by Zhao Yang and Chengxiang Xu

Appl. Sci. 2018, 8(9), 1602; https://doi.org/10.3390/app8091602 - 10 Sep 2018

Cited by 23 | Viewed by 5267

Abstract

Local buckling in steel tubes was observed to be capable of reducing the ultimate loads of thin-walled concrete-filled steel-tube (CFST) columns under axial compression. To strengthen the steel tubes, steel bars were proposed in this paper to be used as stiffeners fixed onto [...] Read more.

Local buckling in steel tubes was observed to be capable of reducing the ultimate loads of thin-walled concrete-filled steel-tube (CFST) columns under axial compression. To strengthen the steel tubes, steel bars were proposed in this paper to be used as stiffeners fixed onto the tubes. Static-loading tests were conducted to study the compression behavior of square thin-walled CFST columns with steel bar stiffeners placed inside or outside the tube. The effect and feasibility of steel bar stiffeners were studied through the analysis of failure mode, load–displacement relationship, ultimate load, ductility, and local buckling. Different setting methods of steel bars were compared as well. The results showed that steel-bar stiffeners proposed in this paper can be effective in delaying local buckling as well as increasing the bearing capacity of the columns, but will decrease the ductility of the columns. In order to obtain a higher bearing capacity of columns, steel bars with low stiffness should be placed inside and steel bars with high stiffness should be placed outside of the steel tubes. The study is helpful in providing reference to the popularization and application of this new structural measure to avoid or delay the local buckling of thin-walled CFST columns. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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19 pages, 11075 KiB

Open AccessArticle

Influence of a New Form of Bolted Connection on the Mechanical Behaviors of a PC Shear Wall

by Shaofei Jiang, Shenghang Lian, Jian Zhao, Xiang Li and Shenglan Ma

Appl. Sci. 2018, 8(8), 1381; https://doi.org/10.3390/app8081381 - 16 Aug 2018

Cited by 14 | Viewed by 3916

Abstract

A variety of forms of connection in precast reinforced concrete (PC) have been proposed, but the impact of the connection forms on the shear wall remains to be studied. In this paper, through quasi-static experiments and numerical simulations, the influences of a new [...] Read more.

A variety of forms of connection in precast reinforced concrete (PC) have been proposed, but the impact of the connection forms on the shear wall remains to be studied. In this paper, through quasi-static experiments and numerical simulations, the influences of a new form of bolted connection on the mechanical behaviors of the PC shear wall are investigated. The results show that the strain of the connector is less than the yield strain and the failure does not occur in the connector; the mechanical behaviors of this connection form of the PC shear wall are equivalent to those of the cast-in-place reinforced concrete (RC) shear wall. Meanwhile, reasonable suggestions are put forward for the design of the connector from the pretightening force, bolt number, and axial compression ratio. This implies that this form of bolted connection has little influence on the mechanical behaviors of the PC shear wall and design suggestions can be used in practical projects. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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24 pages, 9621 KiB

Open AccessArticle

Fire Behavior of U-shaped Steel Beams Filled with Demolished Concrete Lumps and Fresh Concrete

by Bo Wu and Mingming Ji

Appl. Sci. 2018, 8(8), 1361; https://doi.org/10.3390/app8081361 - 13 Aug 2018

Cited by 8 | Viewed by 4409

Abstract

To reuse waste concrete in a more straightforward and simplified way, a new kind of structural member containing fresh concrete (FC) and demolished concrete lumps (DCLs) distinctly larger than conventional recycled aggregates has been proposed. Previous research has shown that, at room temperature, [...] Read more.

To reuse waste concrete in a more straightforward and simplified way, a new kind of structural member containing fresh concrete (FC) and demolished concrete lumps (DCLs) distinctly larger than conventional recycled aggregates has been proposed. Previous research has shown that, at room temperature, the mechanical performance of the U-shaped steel beams filled with DCLs and FC is similar to that of the U-shaped steel beams filled with FC alone. This research explores the fire behavior of the U-shaped steel beams filled with DCLs and FC. Five specimens including three beams filled with DCLs and FC and two reference beams filled with FC alone were tested in fire. The experimental parameters included the replacement ratio of DCLs, the longitudinal reinforcement ratio, the load ratio, and the thickness of fire insulation. Based on the test results, numerical models in which the thermal resistance at the interface between the U-shaped steel and the in-filled concrete is considered are developed using SAFIR to determine the thermal and structural responses of the specimens. Lastly, parametric studies are carried out preliminarily to investigate the effects of some parameters on the fire resistance of such beams. It is found that the replacement ratio of DCLs within a range of 0% to 33% has a very limited effect on the temperature distribution, structural response, and fire resistance of the specimens, that embedding longitudinal reinforcements can significantly increase the fire resistance of such beams, that the interface thermal resistance can generate a temperature drop of up to 280 °C at the interface between the U-shaped steel and the in-filled concrete, and that the numerical models are capable of predicting the thermal and structural responses of such beams. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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17 pages, 10176 KiB

Open AccessArticle

Experimental Study on an Optimized-Section Precast Slab with Structural Aesthetics

by Hyunjin Ju, Sun-Jin Han, Il Sup Choi, Seokdong Choi, Min-Kook Park and Kang Su Kim

Appl. Sci. 2018, 8(8), 1234; https://doi.org/10.3390/app8081234 - 26 Jul 2018

Cited by 14 | Viewed by 5291

Abstract

The optimized-section precast slab with structural aesthetics (OPS) is a half precast concrete slab with multi-ribs that optimizes the cross-section by eliminating the unnecessary bottom flanges at mid-span and has good structural performance by utilizing prestressing strands and truss-type shear reinforcements. In addition, [...] Read more.

The optimized-section precast slab with structural aesthetics (OPS) is a half precast concrete slab with multi-ribs that optimizes the cross-section by eliminating the unnecessary bottom flanges at mid-span and has good structural performance by utilizing prestressing strands and truss-type shear reinforcements. In addition, it is a member that is designed to highlight the structural aesthetics through the curved shape of a variable cross-section at the bottom of the flange which is created from a natural shape that is formed in the section optimization process. In this study, experimental research was carried out to examine the structural performance of the OPS, which includes flexure and shear tests on the precast concrete unit members for resisting construction loads, the composite members with cast-in-place concrete, and the continuous end section. The experiment results confirm that, in accordance with the current design code, the flexural performance of OPS is on the safe side regardless of the member type, whereas the shear performance of the precast concrete unit member differs slightly from that of the composite member due to the differences in the contributions of the shear reinforcement as the effective depth varies. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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15 pages, 1533 KiB

Open AccessArticle

Sensitivity Factors Analysis on the Compressive Strength and Flexural Strength of Recycled Aggregate Infill Wall Materials

by Zongping Chen, Yaqi Zhang, Jianjia Chen and Jie Fan

Appl. Sci. 2018, 8(7), 1090; https://doi.org/10.3390/app8071090 - 5 Jul 2018

Cited by 9 | Viewed by 3081

Abstract

This paper describes an experimental research study designed to evaluate the feasibility of usage of the crushed clay brick and concrete block as fine aggregate raw materials producing recycled aggregate infill wall materials. To better understand the influences of various factors, an investigation [...] Read more.

This paper describes an experimental research study designed to evaluate the feasibility of usage of the crushed clay brick and concrete block as fine aggregate raw materials producing recycled aggregate infill wall materials. To better understand the influences of various factors, an investigation was carried out with 96 specimens made by regenerated brick granule and concrete block. The regenerated brick granule content (regenerated brick granule and concrete granule proportion), water–cement ratio, aggregate–cement ratio, lime content and aggregate replacement rate were considered in an orthogonal experimental design method (DOE method) involving five factors and four factor levels. The mechanical properties of the recycled aggregate infill wall materials (RAIW) between each factor and level were evaluated by compressive strength, flexural strength and the flexural–compressive ratio. The empirical relationship among mechanical properties and factors of recycled aggregate infill wall materials was proposed by using multivariate regression analysis. The results showed that the water–cement ratio was 0.7–0.8 which is especially effective for improving the compressive strength and flexural strength of recycled aggregate infill wall materials, and the aggregate–cement ratio was the most significant factor in the flexural–compressive ratio. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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16 pages, 6448 KiB

Open AccessArticle

Experimental Investigation on the Seismic Behavior of Newly-Developed Precast Reinforced Concrete Block Masonry Shear Walls

by Weifan Xu, Xu Yang and Fenglai Wang

Appl. Sci. 2018, 8(7), 1071; https://doi.org/10.3390/app8071071 - 30 Jun 2018

Cited by 11 | Viewed by 7337

Abstract

Typically, a special type of concrete block with cleaning holes is used in the bottom layer of traditional reinforced masonry shear walls (RMSWs) for mortar cleaning and vertical rebar connection, which results in reduced integrity and weakened structural behavior. In this paper, a [...] Read more.

Typically, a special type of concrete block with cleaning holes is used in the bottom layer of traditional reinforced masonry shear walls (RMSWs) for mortar cleaning and vertical rebar connection, which results in reduced integrity and weakened structural behavior. In this paper, a precast construction technology was introduced to overcome these shortcomings. The cleaning-hole blocks were eliminated in the newly-developed precast RMSWs. Quasi-static tests on two traditional and two precast fully grouted RMSWs were conducted. The results showed that the flexural capacity of precast walls exhibited about a 10% increase when compared to traditional RMSWs under the same axial compression. Precast RMSWs that failed in flexural mode showed favorable deformation capacity and the displacement ductility value corresponding to 15% strength degradation reached 4.9. The wall stiffness degraded rapidly to 50% of the initial stiffness, K₀, at 0.2% drift and, at 0.5% drift, the corresponding stiffness decreased to about 21% K₀ at a more gradual rate. Furthermore, precast RMSWs exhibited significant energy dissipation capacity. The experiment suggests that precast RMSWs have a satisfactory seismic performance. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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14 pages, 3221 KiB

Open AccessArticle

Preliminary Investigation of the Feasibility of Using a Superpave Gyratory Compactor to Design Cement-Treated Aggregate Mixture

by Yinfei Du, Pusheng Liu, Jun Tian, Jian Zhang and Yu Zheng

Appl. Sci. 2018, 8(6), 946; https://doi.org/10.3390/app8060946 - 7 Jun 2018

Cited by 10 | Viewed by 3456

Abstract

Cement-treated aggregate mixture (CTAM) is widely used in many countries. To design this mixture using the vibration compaction method brings about many problems, such as serious inconsistencies in key parameters and strong vibration energy and noise imposed on adjacent buildings and people. This [...] Read more.

Cement-treated aggregate mixture (CTAM) is widely used in many countries. To design this mixture using the vibration compaction method brings about many problems, such as serious inconsistencies in key parameters and strong vibration energy and noise imposed on adjacent buildings and people. This work presents a preliminary investigation of the use of Superpave gyratory compactor, which has been widely used to compact hot mix asphalt in the laboratory, to design CTAM. The 3-2-2 mode of the locking point was used to determine that the gyration compaction number N_design should be 105. The performances of the CTAM specimens prepared using gyration compaction were compared with those prepared using the Proctor and vibration compaction methods. Compared with Proctor and vibration compaction, gyration compaction had a smaller influence on aggregate degradation. Also, the optimal moisture content after gyration compaction was the minimum. The index values for maximum dry density, unconfined compressive strength and dry/temperature shrinkage coefficient after gyration compaction were between those for Proctor compaction and vibration compaction. It can be concluded that it is feasible to design CTAM by using a Superpave gyratory compactor to compact the mixture for 105 cycles. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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17 pages, 2695 KiB

Open AccessArticle

Reliability Study on FRP Composites Exposed to Wet-Dry Cycles

by Hongjun Liang, Shan Li, Yiyan Lu and Ting Yang

Appl. Sci. 2018, 8(6), 892; https://doi.org/10.3390/app8060892 - 30 May 2018

Cited by 13 | Viewed by 3555

Abstract

Due to lack of research data on the rates of deterioration of FRP properties under a harsh environment exposure, it was pointed out in the design guidelines that the durability of FRP needs to be further developed. Therefore, in this study, 48 FRP [...] Read more.

Due to lack of research data on the rates of deterioration of FRP properties under a harsh environment exposure, it was pointed out in the design guidelines that the durability of FRP needs to be further developed. Therefore, in this study, 48 FRP samples were tested under wet-dry cycles exposure. The effect of wet-dry cycling times on the failure modes, tensile strength, and the probability distribution of different FRP (GFRP and CFRP) composite specimens were investigated. The experimental results showed that the wet-dry cycles have a significant adverse influence on the tensile strength, have a certain adverse effect on the elongation, and a very limited influence on the elastic modulus of FRP. According to the experimental results, a probability analysis was conducted on the degradation of tensile strength. Five widely used test methods were adopted to verify the possible distribution types of tensile strength, and a reliability index β was then calculated. Subsequently, the effects of the design tensile strengths of ACI-440, TR-55, GB 50608-2010, GB 50367-2013, European Fib Bulletin 14 and Italian CNR guidelines on the β were investigated. The investigation illustrates that only the design value of the TR-55 code can guarantee sufficient long-term safety of a CFRP composite, whereas all the six codes cannot guarantee the long-term safety of a GFRP composite and the partial safety factors in these codes are still not conservative. Therefore, a more conservative safety factor was suggested. Moreover, the design value of tensile strength needs to be further conservative when the standard deviation of the load is large. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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12 pages, 7172 KiB

Open AccessArticle

Mechanical and Hydraulic Behaviors of Eco-Friendly Pervious Concrete Incorporating Fly Ash and Blast Furnace Slag

by Hua Peng, Jian Yin and Weimin Song

Appl. Sci. 2018, 8(6), 859; https://doi.org/10.3390/app8060859 - 24 May 2018

Cited by 58 | Viewed by 4418

Abstract

Eco-friendly pervious concretes containing fly ash (FA) and blast furnace slag (BFS) were prepared in this study. The compressive strength and hydraulic behaviors were investigated to explore the effect of replacement content of FA and BFS. Rheological tests of cementitious pastes were first [...] Read more.

Eco-friendly pervious concretes containing fly ash (FA) and blast furnace slag (BFS) were prepared in this study. The compressive strength and hydraulic behaviors were investigated to explore the effect of replacement content of FA and BFS. Rheological tests of cementitious pastes were first conducted and the results showed that FA could increase the apparent viscosity and BFS did not change the rheology performance. Compared to traditional concretes, FA and BFS both decreased the compressive strength of pervious concrete at 28 d, while pervious concrete incorporated with FA and/or BFS presented comparable strength at 60 d. Compared to the control concrete mix, at the same replacement rate, FA changed the compressive strength more obviously than BFS. FA and BFS both decreased the effective porosity and permeability coefficient of pervious concrete. However, when the replacement rate (30%) was the same, concretes with ternary blends presented obviously larger porosity than binary blends. The relationships between porosity and permeability, and strength were also established. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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17 pages, 9349 KiB

Open AccessArticle

Residual Axial Bearing Capacity of Concrete-Filled Circular Steel Tubular Columns (CFCSTCs) after Transverse Impact

by Guofeng Du, Anja Andjelic, Zhao Li, Zhen Lei and Xuemeng Bie

Appl. Sci. 2018, 8(5), 793; https://doi.org/10.3390/app8050793 - 16 May 2018

Cited by 26 | Viewed by 4457

Abstract

The purpose of this research is to study the effect of both transverse impact, and ratio of outer diameter to thickness of outer steel tube (D/t), on the residual axial bearing capacity of concrete-filled circular steel tubular columns (CFCSTCs). A total [...] Read more.

The purpose of this research is to study the effect of both transverse impact, and ratio of outer diameter to thickness of outer steel tube (D/t), on the residual axial bearing capacity of concrete-filled circular steel tubular columns (CFCSTCs). A total of sixteen samples, including four samples left untreated for comparison, are experimentally studied to investigate the effect of both drop-hammer transverse impact height (H), and D/t ratio, on the residual axial bearing capacity of CFCSTCs. The failure mode, load-displacement curves, load-strain curves, and residual axial bearing capacity of those samples are extensively investigated. A finite element analysis (FEA) model is established to predict the effect of D/t ratio on the residual axial bearing capacity of CFCSTCs. The results indicate that the H and the D/t ratio have noticeable effects on the axial compression performance of CFCSTCs. Failure mode of samples is commonly local buckling. In addition, maximum reduction of the axial bearing capacity of columns reaches about 35% compared with that of untreated columns. The results also show that the bearing capacity of the column increases with a decreasing D/t ratio of the same diameter (D). Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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21 pages, 5125 KiB

Open AccessArticle

Compressive Behaviors of Prisms Made of Demolished Concrete Lumps and Fresh Concrete

by Bo Wu, Yong Yu and Zongping Chen

Appl. Sci. 2018, 8(5), 743; https://doi.org/10.3390/app8050743 - 8 May 2018

Cited by 10 | Viewed by 3919

Abstract

Directly adopting coarsely crushed demolished concrete lumps (DCLs) with pouring concrete (referred to as fresh concrete, FC) in new structural members has been demonstrated to be more efficient and environmental than the traditional approach of recycling waste concrete as coarse aggregate particles. In [...] Read more.

Directly adopting coarsely crushed demolished concrete lumps (DCLs) with pouring concrete (referred to as fresh concrete, FC) in new structural members has been demonstrated to be more efficient and environmental than the traditional approach of recycling waste concrete as coarse aggregate particles. In this study, 45 prisms made of FC and DCLs were tested under axial compressive loading up to failure. The varied parameters included the dimensions of the prisms, the replacement ratio of DCLs, and the characteristic size of the lumps. The compressive performance of 36 cubes and cylinders was also experimentally examined for comparison. A formula was developed to predict the strength of compound concrete prisms filled with DCLs. Empirical formulas were also established relating a prism’s strength with its elastic modulus and peak strain. It was found that: (a) when the replacement ratio is between 20% and 40%, the strength of a prism is about 1.13 that of a cylinder, due to the casting direction of the prism being different from that of the cylinder; (b) as the size of filler lumps increases relative to the size of the specimen, the strength of prisms decreases faster than that of cylinders, which weaken faster than cubes; and (c) due to the coupling effect of the aggregate size of FC and the specimen size, the compressive strength of prisms first increases with their size and then declines gradually. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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16 pages, 5816 KiB

Open AccessArticle

Evaluation of Fe-Based Shape Memory Alloy (Fe-SMA) as Strengthening Material for Reinforced Concrete Structures

by Kinam Hong, Sugyu Lee, Sanghoon Han and Yeongmo Yeon

Appl. Sci. 2018, 8(5), 730; https://doi.org/10.3390/app8050730 - 5 May 2018

Cited by 49 | Viewed by 6228

Abstract

This paper aims to evaluate potential of an Fe-based shape memory alloy (Fe-SMA) for strengthening civil structures. Mechanical properties of the Fe-SMA were investigated with a direct tensile test, which showed the stress-induced transformation, stress at fracture of the Fe-SMA, and modulus of [...] Read more.

This paper aims to evaluate potential of an Fe-based shape memory alloy (Fe-SMA) for strengthening civil structures. Mechanical properties of the Fe-SMA were investigated with a direct tensile test, which showed the stress-induced transformation, stress at fracture of the Fe-SMA, and modulus of elasticity. Heating temperature ranging from 110

℃

to 220

℃

and pre-straining level ranging from 2% to 8% of the Fe-SMA were considered as variables to provoke a shape memory effect (SME), which generates a recovery stress. The recovery stresses ranged from 207.59 MPa to 438.61 MPa, which plays a role in introducing a pre-stressing force to concrete members. Bonding behavior of the Fe-SMA embedded into a groove with a cement-based mortar filler was investigated to determine the required bonding length to fully develop the pre-stressing force of the Fe-SMA with a near-surface mounted (NSM) strengthening technique. All the tested specimens showed slippage failure and suggested a minimum bonding length of 600 mm. The pre-stressing force applied on the concrete can be calculated with the recovery stress of the Fe-SMA. Based on those test results, the Fe-SMA shows sufficient potential to be used as strengthening material for civil structures. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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25 pages, 8541 KiB

Open AccessArticle

Deep Embedment (DE) FRP Shear Strengthening of Concrete Bridge Slabs under Loads Close to Supports

by Lipeng Xia and Yu Zheng

Appl. Sci. 2018, 8(5), 721; https://doi.org/10.3390/app8050721 - 4 May 2018

Cited by 13 | Viewed by 4205

Abstract

Shear forces are the most common governing failure mechanism of reinforced concrete bridge deck slabs subjected to loads close to their supports. This paper reveals a comprehensive study of the behaviour of concrete slabs shear-strengthened with a deep embedment fibre reinforced polymer (FRP) [...] Read more.

Shear forces are the most common governing failure mechanism of reinforced concrete bridge deck slabs subjected to loads close to their supports. This paper reveals a comprehensive study of the behaviour of concrete slabs shear-strengthened with a deep embedment fibre reinforced polymer (FRP) technique. In the experimental investigation, a series of eight full scale concrete slabs were created and tested up to failure. Several structural variables were changed to assess the effectiveness of this shear strengthening technique. The behaviour of test slabs is discussed and the influence of this strategy was evaluated by comparing the test results. It was shown that brittle shear failures could be avoided by using this strengthening strategy. The ultimate capacity and deflection at the failure were both enhanced by using the deep embedment strengthening method. Additionally, a nonlinear finite element analysis (NLFEA) was proposed to develop further investigation. This NLFEA model gave excellent predictions for the structural behaviour of the test concrete slabs. Finally, a two-way theoretical model was proposed to predict the loading-carrying capacity of concrete slabs strengthened with deep embedment FRP bars. The ultimate strength predicted by this theoretical method showed good agreement with that from the test results. Full article

(This article belongs to the Special Issue Emerging Construction Materials and Sustainable Infrastructure)

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