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A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Construction and Building Materials".

Deadline for manuscript submissions: closed (31 May 2020) | Viewed by 59361

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Dr. Farhad Aslani

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Materials and Structures Innovation Group, School of Engineering, The University of Western Australia, Perth, WA 6009, Australia
Interests: smart and sustainable construction materials; advanced concrete technology (conductive concrete, self-compacting concrete, geopolymer concrete, lightweight concrete, heavyweight concrete, engineered cementitious composite, and ultra-high performance concrete); fire performance of structures; advanced reinforced concrete structures; steel-concrete composite structures; rehabilitation and strengthening techniques; offshore structures; additive manufacturing (3D printing) of cementitious/geopolymer composites
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Dear Colleagues,

The aim of New Advances in Self-Compacting Concrete and Geopolymer Concrete—Special Issue is to publish the best research on self-compacting concrete (SCC) and geopolymer concrete (GC) incorporating fiber reinforcement, lightweight aggregates, heavyweight aggregates, recycled concrete aggregates, tire derived aggregates, recycled glass aggregates, rice husk ash, etc. In doing so, this Special Issue will present the results of research on the properties and performance of SCC and GC; novel experimental techniques; the latest analytical and modelling methods; the examination and the diagnosis of real SCC and GC structures; and the potential for improved and innovative SCC and GC.

Relevant topics to this Special Issue include, but are not limited to the following subjects:

Self-compacting concrete
Geopolymer concrete
Fibers reinforcement
Recycled concrete aggregates
Tire derived aggregates
Lightweight aggregates
Heavyweight aggregates
High temperatures
Durability
Concrete technology

Dr. Farhad Aslani
Guest Editor

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Keywords

Self-compacting concrete
Geopolymer concrete
Fibers reinforcement
Recycled concrete aggregates
Tire derived aggregates
Lightweight aggregates
Heavyweight aggregates
High temperatures
Durability
Concrete technology.

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Published Papers (11 papers)

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Research

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16 pages, 4535 KiB

Open AccessArticle

Influence of Water Content on Mechanical Strength and Microstructure of Alkali-Activated Fly Ash/GGBFS Mortars Cured at Cold and Polar Regions

by Xiaobin Wei, Feng Ming, Dongqing Li, Lei Chen and Yuhang Liu

Materials 2020, 13(1), 138; https://doi.org/10.3390/ma13010138 - 29 Dec 2019

Cited by 25 | Viewed by 3282

Abstract

Negative temperature curing is a very harmful factor for geopolymer mortar or concrete, which will decrease the strength and durability. The water in the geopolymer mixture may be frozen into ice, and the water content is a crucial factor. The purpose of this paper is to explore the influence of water content on the properties of alkali-activated binders mortar cured at −5 °C. Fly ash (FA) and ground granulated blast furnace slag (GGBFS) were used as binders. Three groups of experiments with different water content were carried out. The prepared samples were investigated through uniaxial compression strength test, Scanning electron microscopy (SEM), and X-ray diffraction (XRD) for the determination of their compressive strength, microstructural features, phase, and composition. The results indicated that, the compressive strength of samples basically maintained 25.78 MPa–27.10 MPa at an age of 28 days; for 90 days, the values reached 33.4 MPa–34.04 MPa. The results showed that lower water content is beneficial to improving the early strength of mortar at −5 °C curing condition, while it has little impact on long-term strength. These results may provide references for the design and construction of geopolymer concrete in cold regions. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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29 pages, 11000 KiB

Open AccessArticle

Fresh-State and Mechanical Properties of High-Performance Self-Compacting Concrete with Recycled Aggregates from the Precast Industry

by Tiago Barroqueiro, Pedro R. da Silva and Jorge de de Brito

Materials 2019, 12(21), 3565; https://doi.org/10.3390/ma12213565 - 30 Oct 2019

Cited by 22 | Viewed by 2936

Abstract

The urgent need to change the less positive impacts of the construction industry on the environment, and more specifically the production and use of concrete, is the main motivation for the research for more efficient and environmentally sustainable solutions. This paper presented the results of an experimental campaign whose ultimate goal was to produce high-performance self-compacting concrete (SCC) using recycled aggregates (RA) from the precast industry. The results of the fresh-state and mechanical properties tests performed on six concrete mixes (using RA from the precast industry) were presented. The first concrete mix is a reference mix using natural aggregates only (100% NA), and the remaining five mixes had various contents of fine (FRA) and coarse (CRA) recycled aggregates in concrete’s composition: (2) 25/25% (25% RA); (3) 50/50% (50% RA); (4) 100/100% (100% RA); (5) 0/100% (100% CRA); (6) 100/0% (100% FRA). The results showed that the high-performance concrete mixes with RA from the precast industry performed worse than the reference mix. However, taking into account all the mechanical properties studied, it can be concluded that RA from precast concrete elements are of very good quality and can be incorporated in the production of high-performance SCC. The potential demonstrated by the combined use of fine and coarse recycled aggregates was also emphasized. This type of work is expected to effectively contribute to raise awareness among the various players in the construction industry, particularly in the precast concrete industry, to the feasibility of using RA in significant quantities (notably coarse aggregates) and to the safety needed to assume structural functions, even for applications where high performance is required. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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17 pages, 8505 KiB

Open AccessArticle

Effect of Heat Curing Method on the Mechanical Strength of Alkali-Activated Slag Mortar after High-Temperature Exposure

by Tai Thanh Tran, Hyuk Kang and Hyug-Moon Kwon

Materials 2019, 12(11), 1789; https://doi.org/10.3390/ma12111789 - 2 Jun 2019

Cited by 19 | Viewed by 3244

Abstract

The aim of this work was to study the mechanical strength and microstructure changes of alkali-activated slag mortar (AAS mortar) after being heat treated in the temperature range of 200–1000 °C. The AAS mortar was cured in the ambient condition (20 ± 5 °C, 60 ± 5% RH) (Relative humidity: RH) and high temperature condition (80 °C) for 27 days with three different heating regimes: curing in a dry oven, curing in sealed plastic bags, and in a steam environment. The activator for the AAS synthesis was a mixture of sodium silicate solution (water glass) and sodium hydroxide (NaOH) with a SiO₂/Na₂O weight ratio of 1, and a dosage of 4% Na₂O by slag weight. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) incorporated with energy-dispersive X-ray spectroscopy (EDX) were used to assess the mortar microstructure change. The results revealed that the curing method significantly affected the mechanical strength of AAS at temperatures lower than 800 °C. The heat treatment at late age of 28 days was more beneficial for compressive strength enhancement in specimens without using heat curing methods. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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27 pages, 8004 KiB

Open AccessArticle

Using Carbonated BOF Slag Aggregates in Alkali-Activated Concretes

by Mohammad Mastali, Ahmad Alzaza, Khaled Mohammad Shaad, Paivo Kinnunen, Zahra Abdollahnejad, Bethany Woof and Mirja Illikainen

Materials 2019, 12(8), 1288; https://doi.org/10.3390/ma12081288 - 19 Apr 2019

Cited by 36 | Viewed by 5240

Abstract

This experimental study aimed to develop alkali-activated concretes containing carbonated basic oxygen furnace (BOF) slag aggregates. In the first stage, the impacts of replacing normal aggregates with carbonated BOF slag aggregates in different alkali-activated concretes were determined by assessing mechanical properties (compressive and flexural strengths), morphology, thermogravimetric analyses (TGA), differential thermogravimetry (DTG) and the crystalline phases using X-ray diffraction analysis. Second, the developed plain alkali-activated concrete was reinforced by different fibre types and dosages to limit the negative impacts of the drying shrinkage and to improve strength. Therefore, the effects of using different fibre contents (1% and 1.5% in Vol.) and types (Polyvinyl alcohol [PVA], Polypropylene [PP], basalt, cellulose and indented short-length steel) on hardened state properties were evaluated. These evaluations were expressed in terms of the compressive and flexural strengths, ultrasonic pulse velocity, mass changes, drying shrinkage and efflorescence. Then, the impacts of aggressive conditions on the hardened properties of fibre-reinforced alkali-activated concretes were evaluated under carbonation, high temperature and freeze/thaw tests. The results showed that using carbonated BOF slag aggregates led to obtain higher strength than using normal aggregates in alkali activated concretes. Moreover, the maximum enhancement due to reinforcing the mixtures was recorded in alkali-activated concretes with steel fibres. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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14 pages, 4370 KiB

Open AccessArticle

The Effect of Fine and Coarse Recycled Aggregates on Fresh and Mechanical Properties of Self-Compacting Concrete

by Mahmoud Nili, Hossein Sasanipour and Farhad Aslani

Materials 2019, 12(7), 1120; https://doi.org/10.3390/ma12071120 - 4 Apr 2019

Cited by 78 | Viewed by 5344

Abstract

Today, the use of recycled aggregates as a substitute for a part of the natural aggregates in concrete production is increasing. This approach is essential because the resources for natural aggregates are decreasing in the world. In the present study, the effects of recycled concrete aggregates as a partial replacement for fine (by 50%) and coarse aggregates (by 100%) were examined in the self-compacting concrete mixtures which contain air-entraining agents and silica fumes. Two series of self-compacting concrete mixes have been prepared. In the first series, fine and coarse recycled mixtures respectively with 50% and 100% replacement with air entraining agent were used. In the second series, fine recycled (with 50% replacement) and coarse recycled (with 100% replacement) were used with silica fume. The rheological properties of the self-compacting concrete (SCC) were determined using slump-flow and J-ring tests. The tests of compressive strength, tensile strength, and compressive stress-strain behavior were performed on both series. The results indicated that air-entraining agent and silica fume have an important role in stabilization of fresh properties of the mixtures. The results of tests indicated a decrease in compressive strength, modulus of elasticity, and energy absorption of concrete mixtures containing air entrained agent. Also, the results showed that complete replacement (100%) with coarse recycled material had no significant effect on mechanical strength, while replacement with 50% fine recycled material has reduced compressive strength, tensile strength, and energy absorption. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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25 pages, 12384 KiB

Open AccessArticle

Development of Heavyweight Self-Compacting Concrete and Ambient-Cured Heavyweight Geopolymer Concrete Using Magnetite Aggregates

by Afsaneh Valizadeh, Farhad Aslani, Zohaib Asif and Matt Roso

Materials 2019, 12(7), 1035; https://doi.org/10.3390/ma12071035 - 28 Mar 2019

Cited by 27 | Viewed by 4413

Abstract

Heavyweight self-compacting concrete (HWSCC) and heavyweight geopolymer concrete (HWGC) are new types of concrete that integrate the advantages of heavyweight concrete (HWC) with self-compacting concrete (SCC) and geopolymer concrete (GC), respectively. The replacement of natural coarse aggregates with magnetite aggregates in control SCC and control GC at volume ratios of 50%, 75%, and 100% was considered in this study to obtain heavyweight concrete classifications, according to British standards, which provide proper protection from sources that emit harmful radiations in medical and nuclear industries and may also be used in many offshore structures. The main aim of this study is to examine the fresh and mechanical properties of both types of mixes. The experimental program investigates the fresh properties of HWSCC and HWGC through the slump flow test. However, J-ring tests were only conducted for HWSCC mixes to ensure the flow requirements in order to achieve self-compacting properties. Moreover, the mechanical properties of both type of mixes were investigated after 7 and 28 days curing at an ambient temperature. The standard 100 × 200 mm cylinders were subjected to compressive and tensile tests. Furthermore, the flexural strength were examined by testing 450 × 100 × 100 mm prisms under four-point loading. The flexural load-displacement relationship for all mixes were also investigated. The results indicated that the maximum compressive strength of 53.54 MPa was achieved by using the control SCC mix after 28 days. However, in HWGC mixes, the maximum compressive strength of 31.31 MPa was achieved by 25% magnetite replacement samples. The overall result shows the strength of HWSCC decreases by increasing magnetite aggregate proportions, while, in HWGC mixes, the compressive strength increased with 50% magnetite replacement followed by a decrease in strength by 75% and 100% magnetite replacements. The maximum densities of 2901 and 2896 kg/m³ were obtained by 100% magnetite replacements in HWSCC and HWGC, respectively. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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17 pages, 4261 KiB

Open AccessArticle

Artificial Intelligence Approaches for Prediction of Compressive Strength of Geopolymer Concrete

by Dong Van Dao, Hai-Bang Ly, Son Hoang Trinh, Tien-Thinh Le and Binh Thai Pham

Materials 2019, 12(6), 983; https://doi.org/10.3390/ma12060983 - 25 Mar 2019

Cited by 259 | Viewed by 12118

Abstract

Geopolymer concrete (GPC) has been used as a partial replacement of Portland cement concrete (PCC) in various construction applications. In this paper, two artificial intelligence approaches, namely adaptive neuro fuzzy inference (ANFIS) and artificial neural network (ANN), were used to predict the compressive strength of GPC, where coarse and fine waste steel slag were used as aggregates. The prepared mixtures contained fly ash, sodium hydroxide in solid state, sodium silicate solution, coarse and fine steel slag aggregates as well as water, in which four variables (fly ash, sodium hydroxide, sodium silicate solution, and water) were used as input parameters for modeling. A total number of 210 samples were prepared with target-specified compressive strength at standard age of 28 days of 25, 35, and 45 MPa. Such values were obtained and used as targets for the two AI prediction tools. Evaluation of the model’s performance was achieved via criteria such as mean absolute error (MAE), root mean square error (RMSE), and coefficient of determination (R²). The results showed that both ANN and ANFIS models have strong potential for predicting the compressive strength of GPC but ANFIS (MAE = 1.655 MPa, RMSE = 2.265 MPa, and R² = 0.879) is better than ANN (MAE = 1.989 MPa, RMSE = 2.423 MPa, and R² = 0.851). Sensitivity analysis was then carried out, and it was found that reducing one input parameter could only make a small change to the prediction performance. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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26 pages, 10791 KiB

Open AccessFeature PaperArticle

Impacts of Casting Scales and Harsh Conditions on the Thermal, Acoustic, and Mechanical Properties of Indoor Acoustic Panels Made with Fiber-Reinforced Alkali-Activated Slag Foam Concretes

by Mastali Mohammad, Kinnunen Paivo, Karhu Marjaana, Abdollahnejad Zahra, Korat Lidija, Ducman Vilma, Alzaza Ahmad and Illikainen Mirja

Materials 2019, 12(5), 825; https://doi.org/10.3390/ma12050825 - 11 Mar 2019

Cited by 24 | Viewed by 4751

Abstract

This paper presents experimental results regarding the efficiency of using acoustic panels made with fiber-reinforced alkali-activated slag foam concrete containing lightweight recycled aggregates produced by using Petrit-T (tunnel kiln slag). In the first stage, 72 acoustic panels with dimension 500 × 500 × 35 mm were cast and prepared. The mechanical properties of the panels were then assessed in terms of their compressive and flexural strengths. Moreover, the durability properties of acoustic panels were studied using harsh conditions (freeze/thaw and carbonation tests). The efficiency of the lightweight panels was also assessed in terms of thermal properties. In the second stage, 50 acoustic panels were used to cover the floor area in a reverberation room. The acoustic absorption in diffuse field conditions was measured, and the interrupted random noise source method was used to record the sound pressure decay rate over time. Moreover, the acoustic properties of the panels were separately assessed by impedance tubes and airflow resistivity measurements. The recorded results from these two sound absorption evaluations were compared. Additionally, a comparative study was presented on the results of impedance tube measurements to compare the influence of casting volumes (large and small scales) on the sound absorption of the acoustic panels. In the last stage, a comparative study was implemented to clarify the effects of harsh conditions on the sound absorption of the acoustic panels. The results showed that casting scale had great impacts on the mechanical and physical properties. Additionally, it was revealed that harsh conditions improved the sound properties of acoustic panels due to their effects on the porous structure of materials. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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24 pages, 15214 KiB

Open AccessArticle

Fire Performance of Heavyweight Self-Compacting Concrete and Heavyweight High Strength Concrete

by Farhad Aslani, Fatemeh Hamidi and Qilong Ma

Materials 2019, 12(5), 822; https://doi.org/10.3390/ma12050822 - 11 Mar 2019

Cited by 27 | Viewed by 4224

Abstract

In this study, the fresh and hardened state properties of heavyweight self-compacting concrete (HWSCC) and heavyweight high strength concrete (HWHSC) containing heavyweight magnetite aggregate with 50, 75, and 100% replacement ratio, and their performance at elevated temperatures were explored experimentally. For fresh-state properties, the flowability and passing ability of HWSCCs were assessed by using slump flow, T500 mm, and J-ring tests. Hardened-state properties including hardened density, compressive strength, and modulus of elasticity were evaluated after 28 days of mixing. High-temperature tests were also performed to study the mass loss, spalling of HWSCC and HWHSC, and residual mechanical properties at 100, 300, 600 and 900 °C with a heating rate of 5 °C/min. Ultimately, by using the experimental data, rational numerical models were established to predict the compressive strength and modulus of elasticity of HWSCC at elevated temperatures. The results of the flowability and passing ability revealed that the addition of magnetite aggregate would not deteriorate the workability of HWSCCs and they retained their self-compacting characteristics. Based on the hardened densities, only self-compacting concrete (SCC) with 100% magnetite content, and high strength concrete (HSC) with 75 and 100% magnetite aggregate can be considered as HWC. For both the compressive strength and elastic modulus, decreasing trends were observed by introducing magnetite aggregate to SCC and HSC at an ambient temperature. Mass loss and spalling evaluations showed severe crack propagation for SCC without magnetite aggregate while SCCs containing magnetite aggregate preserved up to 900 °C. Nevertheless, the mass loss of SCCs containing 75 and 100% magnetite content were higher than that of SCC without magnetite. Due to the pressure build-up, HSCs with and without magnetite showed explosive spalling at high temperatures. The residual mechanical properties analysis indicated that the highest retention of the compressive strength and modulus of elasticity after exposure to elevated temperatures belonged to HWSCC with 100% magnetite content. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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24 pages, 23848 KiB

Open AccessArticle

Properties of Ambient-Cured Normal and Heavyweight Geopolymer Concrete Exposed to High Temperatures

by Farhad Aslani and Zohaib Asif

Materials 2019, 12(5), 740; https://doi.org/10.3390/ma12050740 - 4 Mar 2019

Cited by 47 | Viewed by 5710

Abstract

Ambient-cured heavyweight geopolymer concrete (HWGC) is a new type of concrete that combines the benefits of both heavyweight concrete (HWC) and geopolymer concrete (GC). HWGC provides proper protection from the sources that emit harmful radiations in medical and nuclear industries. Furthermore, HWGC may also be used in offshore structures for pipeline ballasting and similar underwater structures. In this study, heavyweight aggregates (magnetite) have been used and replaced by normal-weight coarse aggregates in GC at volume ratios of 50, 75, and 100% to attain heavyweight classification according to British standards. This study investigates the impacts of high temperatures on standard ambient-cured geopolymer concrete and ambient-cured HWGC through its residual properties regarding compressive and tensile strengths, mass loss, spalling intensity, and flexural strength. The residual properties were examined by heating 100 × 200 mm cylinder specimens to 100, 300, 600, and 900 °C. The results indicated that the maximum compressive strengths of 40.1 and 39.0 MPa were achieved by HWGC at 300 and 100 °C, respectively. The overall result shows that the strength of HWGC increases by increasing magnetite aggregate proportion, while the mass loss, intensity of spalling, and loss of strengths is proportional to temperature after a certain point. Minor spalling with holes and cracking was observed only at 900 °C in HWGC. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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19 pages, 2464 KiB

Open AccessReview

A Review of Durability and Strength Characteristics of Alkali-Activated Slag Concrete

by Osama Ahmed Mohamed

Materials 2019, 12(8), 1198; https://doi.org/10.3390/ma12081198 - 12 Apr 2019

Cited by 91 | Viewed by 6564

Abstract

Alkali-activated slag (AAS) is a promising alternative to ordinary Portland cement (OPC) as sole binder for reinforced concrete structures. OPC is reportedly responsible for over 5% of the global CO₂ emission. In addition, slag is an industrial by-product that must be land-filled if not re-used. Therefore, it has been studied by many investigators as environmentally friendly replacement of OPC. In addition to recycling, AAS offers favorable properties to concrete such as rapid development of compressive strength and high resistance to sulfate attack. Some of the potential shortcomings of AAS include high shrinkage, short setting time, and high rate of carbonation. Using ground granulated blast furnace slag (GGBS) as an alternative to OPC requires its activation with high alkalinity compounds such as sodium hydroxide (NaOH), sodium sulfate (Na₂SO₃), sodium carbonate (Na₂CO₃), or combination of these compounds such as NaOH and Na₂SO₃. The mechanism of alkali-activation is still not fully understood and further research is required. This paper overviews the properties, advantages, and potential shortcomings of AAS concrete. Full article

(This article belongs to the Special Issue New Advances in Self-Compacting Concrete and Geopolymer Concrete)

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