Polymers

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2 pages, 164 KiB

Open AccessEditorial

Preparation, Structure and Characterization of Polymer/Cement Composites

by Bowen Guan

Polymers 2023, 15(11), 2495; https://doi.org/10.3390/polym15112495 - 29 May 2023

Viewed by 3084

Abstract

Polymer/cement composites have gained significant attention in civil engineering due to their improved properties compared to traditional cement-based materials [...] Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

Research

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24 pages, 16002 KiB

Open AccessArticle

Hybrid Composite Materials Made of Recycled PET and Standard Polymer Blends Used in Civil Engineering

by Daniel Papán, Lenka Lapašová and Zuzana Papánová

Polymers 2023, 15(16), 3407; https://doi.org/10.3390/polym15163407 - 14 Aug 2023

Viewed by 2268

Abstract

This paper presents an investigation of the tensile properties of two composites made from recycled polyethylene tetraphthalate, cement–concrete mix and standard polymer-based adhesive mixes, used in the construction industry. To describe tensile behavior, experimental measurements of each component of the resulting composite materials [...] Read more.

This paper presents an investigation of the tensile properties of two composites made from recycled polyethylene tetraphthalate, cement–concrete mix and standard polymer-based adhesive mixes, used in the construction industry. To describe tensile behavior, experimental measurements of each component of the resulting composite materials were processed in detail. It presents the possibilities of modifying materials suitable for building structures and at the same time provides an opportunity to get rid of polyethylene tetraphthalate (PET), which has already been recycled several times. Because the resulting composite contains a majority of the composite composition on a fragile basis, its use in practice depends on its simple thrust properties. In this paper, a study of the most important mechanical properties of a previously unused composite is presented. These properties were obtained experimentally using an innovative tensile test method. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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12 pages, 7602 KiB

Open AccessArticle

Determining the Long-Term Skid Resistance of Steel Slag Asphalt Mixture Based on the Mineral Composition of Aggregates

by Kuo Ji, Changchun Shi, Jing Jiang, Yaogang Tian, Xiaowei Zhou and Rui Xiong

Polymers 2023, 15(4), 807; https://doi.org/10.3390/polym15040807 - 6 Feb 2023

Cited by 3 | Viewed by 1783

Abstract

This study intends to predict the long-term skid resistance of steel slag asphalt mixture (SSAM) from the mineral composition of the aggregates. The polished stone value (PSV) and mineral composition of the aggregates were assessed using the accelerated polishing test and X-ray diffraction, [...] Read more.

This study intends to predict the long-term skid resistance of steel slag asphalt mixture (SSAM) from the mineral composition of the aggregates. The polished stone value (PSV) and mineral composition of the aggregates were assessed using the accelerated polishing test and X-ray diffraction, respectively. The hardness (H) and surface texture richness (STR) of the aggregates were calculated from the mineral composition of the aggregates, and then a multivariate linear model was established between PSV and H and STR. The British pendulum number (BPN) and three-dimensional morphology of the SSAM were then evaluated using a British pendulum and a pavement laser scanner, respectively. Finally, an exponential relationship was established between BPN, aggregate PSV, and various aggregate amounts of SSAM. The results show that steel slag with H, STR, and PSV was better than natural aggregates and can significantly improve the skid resistance of pavement, but the relationship between steel slag content and long-term skid resistance of SSAM was not linear, and SSAM with 50% steel slag content had the best skid resistance. The mathematical model developed can predict the long-term skid resistance of SSAM from the mineral composition of the aggregates. The model can be used by designers to predict the long-term skid resistance of steel slag asphalt pavements at the design stage and thus better determine the proportion of steel slag to other aggregates. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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25 pages, 7061 KiB

Open AccessArticle

Research on Performance Deterioration of Internally Cured Pavement Concrete under the Coupling Effect of Salt Freeze–Thaw

by Jieting Xu, Xiao Qin, Yongkang Lin, Chaofeng Cao, Junhong Liu and Qingjian Huang

Polymers 2023, 15(3), 476; https://doi.org/10.3390/polym15030476 - 17 Jan 2023

Cited by 5 | Viewed by 1588

Abstract

This paper aims at solving the material durability problem caused by spraying deicing salt on pavement concrete in the northern winter. Super absorbent polymer (SAP) was adopted as an internal curing agent to enhance the durability of pavement concrete. Curing parameters including particle [...] Read more.

This paper aims at solving the material durability problem caused by spraying deicing salt on pavement concrete in the northern winter. Super absorbent polymer (SAP) was adopted as an internal curing agent to enhance the durability of pavement concrete. Curing parameters including particle size and dosage of SAP and curing condition were optimized based on mortar tests by means of the grey target decision method. The deterioration rule of durability and mechanical properties of pavement concrete internally cured by different SAP dosages after salt freeze–thaw cycles were explored through rapid freeze–thaw test. Combined with the characteristics of pore structure, hydration and microstructure, the influence mechanism of SAP on the salt freeze–thaw resistance of pavement concrete was revealed. The experimental results showed that: (i) The reduction in mass loss rate and relative dynamic modulus was significantly improved by SAP internal curing with moderate dosage; (ii) The more freeze–thaw cycles the specimen underwent, the greater the increase in strength; (iii) After 75 cycles, the chloride ion erosion depth could be decreased by approximately 23.18%. Moreover, the addition of SAP could refine the pore size, inhibit the generation of shrinkage microcracks, and promote the degree of cement hydration in the late stage, which improved the internal density of the cement concrete structure. Therefore, the deterioration of pavement under the coupling effect of salt freeze–thaw was reduced. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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19 pages, 5897 KiB

Open AccessArticle

Effects of Fly Ash and Hexadecyltrimethoxysilane on the Compressive Properties and Water Resistance of Magnesium Oxychloride Cement

by Bowen Guan, Zhenqing He, Fulu Wei, Faping Wang and Jincheng Yu

Polymers 2023, 15(1), 172; https://doi.org/10.3390/polym15010172 - 29 Dec 2022

Cited by 6 | Viewed by 1821

Abstract

The application of magnesium oxychloride cement (MOC) is promising, but its poor water resistance seriously hinders its development and application. In this paper, we describe a new type of MOC with excellent water resistance, prepared using fly ash and hexadecyltrimethoxysilane (HDTMS). SEM, XRD, [...] Read more.

The application of magnesium oxychloride cement (MOC) is promising, but its poor water resistance seriously hinders its development and application. In this paper, we describe a new type of MOC with excellent water resistance, prepared using fly ash and hexadecyltrimethoxysilane (HDTMS). SEM, XRD, FTIR, TG/DSC, and other microscopic-scale studies were conducted to investigate the mechanism underlying the water-resistance enhancement of the new MOC. It was found that adding 20% fly ash and 3% HDTMS can strengthen the water resistance of MOC while retaining high mechanical properties. In particular, the residual coefficient remained at 0.91 after 7 days of immersion. This is because these two additives, when used together, can increase the content of the gelling 5-phase of MOC, as well as optimize the pore structure of MOC. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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20 pages, 8669 KiB

Open AccessArticle

Comparative Study of Octavinyl Oligomeric Sesquisiloxane Nanomaterial-Modified Asphalt Using Molecular Dynamics Method

by Lei Feng, Peng Zhao, Tongdan Chen and Minghai Jing

Polymers 2022, 14(21), 4577; https://doi.org/10.3390/polym14214577 - 28 Oct 2022

Cited by 8 | Viewed by 1593

Abstract

This paper mainly studies the compatibility and properties of octavinyl oligomeric silsesquioxane nanomaterial (nano-OvPOSS)-modified asphalt, in comparison with those of traditional zinc oxide nanomaterial (nano-ZnO) and silica nanomaterial (nano-SiO₂), through the method of molecular dynamics simulation. Nano-OvPOSS, an organic–inorganic nano-hybrid material, [...] Read more.

This paper mainly studies the compatibility and properties of octavinyl oligomeric silsesquioxane nanomaterial (nano-OvPOSS)-modified asphalt, in comparison with those of traditional zinc oxide nanomaterial (nano-ZnO) and silica nanomaterial (nano-SiO₂), through the method of molecular dynamics simulation. Nano-OvPOSS, an organic–inorganic nano-hybrid material, is studied for the first time in the application of asphalt modification. By studying different sizes and types of nanomaterials, this paper elucidates the superiority of nano-OvPOSS as an asphalt modifier owing to the unique microstructure of eight organic groups of its inorganic framework. According to the results, nano-OvPOSS does not aggregate in the modified asphalt system and displays the best compatibility with asphalt when compared with nano-SiO₂ and nano-ZnO. Moreover, nano-OvPOSS exhibits the most favorable compatibility with resinous oil out of the four asphalt components. The size of nano-OvPOSS determines its compatibility with asphalt. The smaller the particle size of nano-OvPOSS, the better its compatibility with asphalt. Therefore, out of all the four sizes of nano-OvPOSS (4.4 Å, 7 Å, 10 Å, and 20 Å) adopted in this study, the 4.4 Å nano-OvPOSS exhibits the best compatibility with asphalt. Additionally, compared with nano-SiO₂ and nano-ZnO, nano-OvPOSS is capable of attracting more asphalt molecules around it so that it reduces the largest amount of ratio of free volume (RFV) of matrix asphalt, which can be reduced by 9.4%. Besides these characteristics, the addition of nano-OvPOSS into the matrix asphalt contributes to higher heat capacity, bulk modulus, and shear modulus of the asphalt system, which were increased by 14.3%, 74.7%, and 80.2%, respectively, thereby guaranteeing a more desirable temperature stability and deformation resistance in the asphalt system. Accordingly, nano-OvPOSS can be employed as a viable asphalt modifier to ensure a well-rounded performance of modified asphalt. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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17 pages, 6441 KiB

Open AccessArticle

Experimental Investigation of Cracking and Impact Resistance of Polymer- and Fiber-Enhanced Concrete for Ultra-Thin Whitetopping

by Liangliang Chen, Shaopeng Zheng, Xiao Li, Zhihao Cheng and Xiaonan Wang

Polymers 2022, 14(21), 4472; https://doi.org/10.3390/polym14214472 - 22 Oct 2022

Cited by 4 | Viewed by 1665

Abstract

In order to investigate the effectiveness of polymer modification and fiber reinforcement on the cracking and impact resistance of concrete materials prepared for ultra-thin whitetopping (UTW), carboxyl butyl benzene latex and polyformaldehyde fibers were added to the conventional cement concrete mix. In addition, [...] Read more.

In order to investigate the effectiveness of polymer modification and fiber reinforcement on the cracking and impact resistance of concrete materials prepared for ultra-thin whitetopping (UTW), carboxyl butyl benzene latex and polyformaldehyde fibers were added to the conventional cement concrete mix. In addition, test methods that used an asphalt mixture performance tester (AMPT) and mechanical rammer were developed to evaluate concrete cracking and impact resistance, respectively. Results from the AMPT test revealed that the cracking resistance can be enhanced with polymer and fiber, especially the initial tensile load peak, which can be improved by more than 40% when fiber and polymer compound modification is applied. Meanwhile, the impact loading test revealed that the inclusion of both fiber and polymer results in a two-fold increase in the number of impacts before visible cracking occurs, and the number of blows to failure increased by 21.4%. Moreover, microstructures were investigated by scanning electron microscopy (SEM) to confirm the reinforcing mechanism of both polymer modification and fiber reinforcement. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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19 pages, 4182 KiB

Open AccessArticle

Analysis of the Influence of Production Method, Plastic Content on the Basic Performance of Waste Plastic Modified Asphalt

by Haibin Li, Lichang Zhou, Jianmei Sun, Sirui Wang, Mingming Zhang, Yihong Hu and Ahmed Abdulakeem Temitope

Polymers 2022, 14(20), 4350; https://doi.org/10.3390/polym14204350 - 15 Oct 2022

Cited by 13 | Viewed by 2402

Abstract

The sustainable reuse of waste plastic as an alternative construction material has numerous environmental and economic advantages. New opportunities to recycle waste plastic in asphalt for road construction would mitigate landfill issues and significantly reduce global carbon emissions. With a clear aim to [...] Read more.

The sustainable reuse of waste plastic as an alternative construction material has numerous environmental and economic advantages. New opportunities to recycle waste plastic in asphalt for road construction would mitigate landfill issues and significantly reduce global carbon emissions. With a clear aim to contribute to a more efficient reuse of waste plastic, this paper reutilized two types of waste plastic (polypropylene (PP) and polyethylene (PE)) as asphalt modifiers to improve the performance of asphalt pavement as well as to achieve the purpose of sustainable recycling waste plastic. Therefore, the optimal preparation parameters of plastic-modified asphalt were recommended by the orthogonal test. Then, the dispersion and modification mechanisms of plastic particles in plastic-modified asphalt were further studied by Fourier Transform Infrared Spectroscopy (FTIR) and Thermogravimetric Differential Scanning Calorimetry (TG-DSC). The results show that the asphalt containing PP and PE shows better overall performance at high temperatures compared with the base asphalt. Furthermore, PE-modified asphalt and PP-modified asphalt exhibited optimal properties when prepared at 3000 rpm for 30 min at 170 °C. Moreover, the results of the expansion mechanism show that the main reaction process of plastic asphalt is a physical change. Finally, PP-modified asphalt and PE-modified asphalt generally perform well and are suitable for high-temperature areas. Consequentially, the results of this research promote the recycling of waste plastic, ultimately advocating the recycling of waste materials and environmental protection of pavement construction. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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26 pages, 9923 KiB

Open AccessArticle

Polymer Foam Concrete FC500 Material Behavior and Its Interaction in a Composite Structure with Standard Cement Concrete Using Small Scale Tests

by Daniel Papán, Daniel Ďugel, Zuzana Papánová and Martin Ščotka

Polymers 2022, 14(18), 3786; https://doi.org/10.3390/polym14183786 - 10 Sep 2022

Cited by 2 | Viewed by 2046

Abstract

This paper focuses on the investigation of the material properties of FC500 foam concrete. Innovation is very important for the solution of cast-in-place concrete forms in practice today. Part of its innovative construction application is the possibility of using foam concrete in a [...] Read more.

This paper focuses on the investigation of the material properties of FC500 foam concrete. Innovation is very important for the solution of cast-in-place concrete forms in practice today. Part of its innovative construction application is the possibility of using foam concrete in a composite structure and the use of its mechanical properties in the load-bearing parts of civil engineering structures. The method of detecting the mechanical properties of foam concrete by using non-standard cantilever test is also innovative. Here, an advanced approach of modelling specimens using powerful computational systems based on the finite element method is used. This modern material is researched especially for its use in transportation structures. For its application, it is necessary to define its resistance to mechanical loads. The main content of the research consists of correlations between experimental measurements and analytical and numerical results. This is the principle of quasi-linear identification of the non-linear behavior of polymeric cementitious porous material during tests on specimens. The focus of the research is an extensive experiment: measurements of the deformation of the specimens until failure. The following methods were chosen to investigate the material properties: small cantilever test, standard tensile test and compression test. The cantilever test was performed for the individual components of the FC500 composite and cement concrete, but also as a compact composite. Numerical simulation models were developed to correlate the individual results in order to validate the uniaxial test results. The conclusions of the research led to the definition of standardized stress–strain diagrams of the FC500 material for compression and especially tension. This is a definition of the behavior of this polymer composite, usable for the development of numerical models of full-scale structures. The results of the research will be applied in the development of national standards for the use of advanced materials in transportation structures (cycle paths, parking lots, traffic playgrounds, lightly trafficked forest roads and trails, etc.). Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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18 pages, 8136 KiB

Open AccessArticle

Strength of Coarse-Grained Soil Stabilized by Poly (Vinyl Alcohol) Solution and Silica Fume under Wet–Dry Cycles

by Zhewei Zhao, Wenwei Li, Haiping Shi, Zhongyao Li, Jiahuan Li, Cheng Zhao and Peiqing Wang

Polymers 2022, 14(17), 3555; https://doi.org/10.3390/polym14173555 - 29 Aug 2022

Cited by 4 | Viewed by 1977

Abstract

To investigate an environmentally benign stabilizer for coarse-grained soil in southeast Tibet, poly (vinyl alcohol) (PVA) and silica fume were used to improve the geotechnical properties of coarse-grained soil. Unconfined compressive strength (UCS) and wet–dry cycle tests were conducted on prepared samples to [...] Read more.

To investigate an environmentally benign stabilizer for coarse-grained soil in southeast Tibet, poly (vinyl alcohol) (PVA) and silica fume were used to improve the geotechnical properties of coarse-grained soil. Unconfined compressive strength (UCS) and wet–dry cycle tests were conducted on prepared samples to evaluate the effect of the additive content and curing age on the strength and durability of coarse-grained soil. The results reveal that the UCS of the samples increased with the additive content of PVA solution and the curing age. The optimal value for the additive content of PVA solution and the curing age is 12% and 7 days, respectively. With the optimal PVA solution content, the PVA solution combined with silica fume stabilizer exhibited better reinforcement compared with pristine PVA. The UCS of the samples stabilized by PVA solution and silica fume increased depending on the curing age, and plateaued after 14 days. Samples with 12% PVA solution and 6% silica fume achieved a satisfactory UCS of 1543.17 kPa after curing for 28 days. As the number of wet–dry cycles increased, the UCS of the samples stabilized by the PVA solution and silica fume exhibited an upward trend during the first three wet–dry cycles, owing to the filling of pores by the gel produced by the silica fume, but began to decline as the number of wet–dry cycles increased. All samples retained a high UCS value after 10 wet-dry cycles compared with the samples that were not subjected to wet–dry cycles. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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21 pages, 11408 KiB

Open AccessArticle

Performance Evaluation of Ultra-Thin Wearing Course with Different Polymer Modified Asphalt Binders

by Jiangmiao Yu, Yanlin Chen, Xiaopeng Wei, Niya Dong and Huayang Yu

Polymers 2022, 14(16), 3235; https://doi.org/10.3390/polym14163235 - 9 Aug 2022

Cited by 14 | Viewed by 2595

Abstract

Ultra-thin wearing course (UTWC) as an asphalt overlay is widely used in pavement maintenance for extending pavement service life. Researchers focused on improving and evaluating its performance, yet few researchers compare the performance of typical UTWCs. Moreover, some traditional asphalt mixture tests are [...] Read more.

Ultra-thin wearing course (UTWC) as an asphalt overlay is widely used in pavement maintenance for extending pavement service life. Researchers focused on improving and evaluating its performance, yet few researchers compare the performance of typical UTWCs. Moreover, some traditional asphalt mixture tests are improper for UTWC due to the thicknesses of UTWC, which is thinner than the traditional asphalt overlay. This study further evaluated the advantages and disadvantages of typical UTWCs. A series of tests were conducted to compare the comprehensive performance of three typical UWTC products, including SMA-10, Novachip-B, and GT-10. Moreover, this study improved the rutting test to evaluate its rutting performance more accurately. Rutting specimens of 20 mm thick and 50 mm thick composite specimens (20 mm UTWC + 30 mm Portland cement concrete slabs) were prepared. Two types of PCC slabs were used, including unprocessed PCC slabs and PCC slabs with preset cracks. The test results showed that Novachip-B showed the best water stability and weakest raveling resistance, while GT-10 showed the best fatigue and anti-skid performance. The rutting performance of UTWCs was reduced because of the influence of preset cracks. The rutting depth of GT-10 was only 60–90% of that of others, showing the comprehensive performance of GT-10 was better than that of others. These results provide a significant reference for the research and application of UTWC. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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11 pages, 1877 KiB

Open AccessArticle

Effect of Sodium Carboxymethyl Cellulose on Water and Salt Transport Characteristics of Saline–Alkali Soil in Xinjiang, China

by Jihong Zhang, Quanjiu Wang, Yuyang Shan, Yi Guo, Weiyi Mu, Kai Wei and Yan Sun

Polymers 2022, 14(14), 2884; https://doi.org/10.3390/polym14142884 - 16 Jul 2022

Cited by 17 | Viewed by 2325

Abstract

The scientific use of sodium carboxymethyl cellulose (CMC) to improve the production capacity of saline–alkali soil is critical to achieve green agriculture and sustainable land use. It serves as a foundation for the scientific use of CMC to clarify the water and salt [...] Read more.

The scientific use of sodium carboxymethyl cellulose (CMC) to improve the production capacity of saline–alkali soil is critical to achieve green agriculture and sustainable land use. It serves as a foundation for the scientific use of CMC to clarify the water and salt transport characteristics of CMC-treated soil. In this study, a one-dimensional soil column infiltration experiment was carried out to investigate the effects of different CMC dosages (0, 0.2, 0.4, 0.6, and 0.8 g/kg) on the infiltration characteristics, infiltration model parameters, water and salt distribution, and salt leaching of saline–alkali soil in Xinjiang, China. The results showed that the final cumulative infiltration of CMC-treated soil increased by 8.63–20.72%, and the infiltration time to reach the preset wetting front depth increased by 1.02–3.96 times. The sorptivity (S) in the Philip infiltration model and comprehensive shape coefficient (α) in the algebraic infiltration model showed a trend of increasing first and then decreasing with CMC dosage, revealing a quadratic polynomial relationship. The algebraic model could accurately simulate the water content profile of CMC-treated soil. CMC enhanced the soil water holding capacity and salt leaching efficiency. The average soil water content, desalination rate, and leaching efficiency were increased by 5.18–15.54%, 21.17–57.15%, and 11.61–30.18%, respectively. The effect of water retention and salt inhibition on loamy sand was the best when the CMC dosage was 0.6 g/ kg. In conclusion, the results provide a theoretical basis for the rational application of CMC to improve saline–alkali soil in arid areas. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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12 pages, 1120 KiB

Open AccessEditor’s ChoiceArticle

Experimental Investigation of the Different Polyacrylamide Dosages on Soil Water Movement under Brackish Water Infiltration

by Jihong Zhang, Quanjiu Wang, Weiyi Mu, Kai Wei, Yi Guo and Yan Sun

Polymers 2022, 14(12), 2495; https://doi.org/10.3390/polym14122495 - 19 Jun 2022

Cited by 11 | Viewed by 1961

Abstract

The use of soil conditioners in conjunction with brackish water irrigation is critical for the efficient development and use of brackish water as well as the enhancement of the structure of saline soil and stimulating crop growth. This study investigated the effects of [...] Read more.

The use of soil conditioners in conjunction with brackish water irrigation is critical for the efficient development and use of brackish water as well as the enhancement of the structure of saline soil and stimulating crop growth. This study investigated the effects of different polyacrylamide (PAM) dosages (0, 0.02%, 0.04%, and 0.06%) on the water flow properties of sandy loam during brackish water infiltration using one-dimensional vertical and horizontal soil column infiltration experiments. The results showed that: (1) PAM could lower the soil infiltration rate and increase soil water retention performance under brackish water infiltration conditions. (2) PAM had a significant effect on the parameters of the Philip and Kostiakov infiltration models. The soil sorption rate S and the empirical coefficient λ were the smallest, and the empirical index β was the largest when the PAM dosage was 0.04%. (3) PAM dosage displayed a quadratic polynomial connection with the soil saturated water content and the saturated hydraulic conductivity. The soil saturated water content was highest when the PAM dosage was 0.04%, the intake suction h_d of the Brooks-Corey model increased by 15.30%, and the soil water holding capacity was greatly improved. (4) Soil treated with PAM could absorb more water under the same soil water suction, whereas the soil unsaturated hydraulic conductivity and its growth rate decreased. The soil saturated diffusion rate D_s, as well as the soil water diffusion threshold, rose. Finally, the 0.04% PAM dosage could improve soil hydrodynamic characteristics under brackish water infiltration, which is beneficial for the efficient utilization of brackish water. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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19 pages, 7000 KiB

Open AccessArticle

Effects of Type and Content of Fibers, Water-to-Cement Ratio, and Cementitious Materials on the Shrinkage and Creep of Ultra-High Performance Concrete

by Ying Chen, Peng Liu, Fei Sha, Zhiwu Yu, Sasa He, Wen Xu and Maofeng Lv

Polymers 2022, 14(10), 1956; https://doi.org/10.3390/polym14101956 - 11 May 2022

Cited by 14 | Viewed by 2780

Abstract

The effects of the type and content of fibers, water to cement ratio (W/C), and content of cementitious materials on the shrinkage and creep of ultra-high performance concrete (UHPC) were investigated. The relationships between curing age, shrinkage, and unit creep of [...] Read more.

The effects of the type and content of fibers, water to cement ratio (W/C), and content of cementitious materials on the shrinkage and creep of ultra-high performance concrete (UHPC) were investigated. The relationships between curing age, shrinkage, and unit creep of the UHPC were also discussed. The results showed that the shrinkage of the UHPC decreased with the increase in W/C, where there existed a quadratic function between shrinkage and W/C. However, the unit creep of the UHPC increased with W/C. The shrinkage and unit creep of the UHPC increased with the increase in the content of the cementitious materials. The type and content of fibers had different effects on the shrinkage and unit creep of the UHPC, that is, the shrinkage of the UHPC first increased and then decreased with the increase in the content of steel fibers, where there existed a quadratic function between them. There was a linear function between the shrinkage of the UHPC and the content of carbon fibers, but the shrinkage of the UHCP first increased and then decreased with the increase in PVA content. The shrinkage and unit creep of the UHPC at the initial curing age were significant, which tended to be constant with the increase in curing age. Although the steel fibers had a significant inhibiting effect on the unit creep of the UHPC, the carbon fibers and PVA had positive and negative effects on the unit creep of the UHPC. The effects of the type and content of fibers on the shrinkage and unit creep of the UHPC were caused by the slenderness ratio, shape, surface roughness, and elasticity modulus of the fibers. The shrinkage and creep of the UHPC were caused by the chemical autogenous shrinkage and free water evaporation of the UHPC. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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Review

Jump to: Editorial, Research

24 pages, 29573 KiB

Open AccessReview

Maximizing the Application of RAP in Asphalt Concrete Pavements and Its Long-Term Performance: A Review

by Jialin Zhang, Taiwo Sesay, Qinglong You and Hongjun Jing

Polymers 2022, 14(21), 4736; https://doi.org/10.3390/polym14214736 - 4 Nov 2022

Cited by 10 | Viewed by 6949

Abstract

The use of recycled asphalt pavement (RAP) materials in asphalt concrete pavements (ACP) brings significant cost and environmental benefits. In practice, however, the amount of RAP readily available far exceeds the amount being utilized in ACPs, which still leaves the problem of excess [...] Read more.

The use of recycled asphalt pavement (RAP) materials in asphalt concrete pavements (ACP) brings significant cost and environmental benefits. In practice, however, the amount of RAP readily available far exceeds the amount being utilized in ACPs, which still leaves the problem of excess RAP in the environment partially solved. Additionally, ACPs containing RAP materials (i.e., RAP-ACPs) can still be landfilled after they have reached the end of their useful life, which may restore the original environmental waste problem. To address these, researchers have demonstrated different ways to maximize the application of RAP in ACPs. Among them, the use of RAP in pavement preventive maintenance (PPM) treatments and the repeated recycling of RAP-ACPs (i.e., RⁿAP) are specifically discussed in this review. It is envisaged that, by promoting these two practices, the application and benefits of RAP can be further maximized to improve sustainability. This review also discusses the long-term behavior of RAP-ACP, which is crucial to inspire confidence in the wider application of RAP in ACP. Studies on RAP-PPM have shown that virgin PPM treatments can successfully accommodate RAP materials by adjusting their mix design. So far, research on RⁿAP has been limited to how multiple-recycling affects the performance properties of the blends, showing improvements in rutting resistance and moisture susceptibility but little effect on linear viscoelasticity and cracking. Overall, the lack of sufficient research is considered to be the biggest challenge in facilitating the implementation of these two sustainable RAP technologies. Little or nothing is known about the bonding mechanisms between RAP and fresh PPM binders, the molecular and chemical changes in RⁿAP binders, or the functional performance characteristics, actual pavement performance, and long-term performance of both RAP-PPM and RⁿAP blends. An understanding of these aspects is very relevant to maximize and continue the beneficial reuse of RAP in ACPs while safeguarding human and environmental health. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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25 pages, 4119 KiB

Open AccessReview

Application of Atomic Force Microscopy as Advanced Asphalt Testing Technology: A Comprehensive Review

by Qijian Ouyang, Zhiwei Xie, Jinhai Liu, Minghui Gong and Huayang Yu

Polymers 2022, 14(14), 2851; https://doi.org/10.3390/polym14142851 - 13 Jul 2022

Cited by 19 | Viewed by 3225

Abstract

In the past three decades, researchers have engaged in the relationship between the composition, macro performance, and microstructure of asphalt. There are many research results in the use of atomic force microscopy (AFM) to study the microstructure and related mechanisms of asphalt. Based [...] Read more.

In the past three decades, researchers have engaged in the relationship between the composition, macro performance, and microstructure of asphalt. There are many research results in the use of atomic force microscopy (AFM) to study the microstructure and related mechanisms of asphalt. Based on previous studies, the performance of asphalt from its microstructure has been observed and analyzed, and different evaluation indices and modification methods have been proposed, providing guidance toward improving the performance of asphalt materials and benefiting potential applications. This review focuses on the typical application and analysis of AFM in the study of the aging regeneration and modification properties of asphalt. Additionally, this review introduces the history of the rheological and chemical testing of asphalt materials and the history of using AFM to investigate asphalt. Furthermore, this review introduces the basic principles of various modes of application of AFM in the microstructure of asphalt, providing a research direction for the further popularization and application of AFM in asphalt or other materials in the future. This review aims to provide a reference and direction for researchers to further popularize the application of AFM in asphalt and standardize the testing methods of AFM. This paper is also helpful in further exploring the relationship between the microstructure and macro performance of asphalt. Full article

(This article belongs to the Special Issue Preparation, Structure and Characterization of Polymer/Cement Composites)

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