Editorial

4 pages, 205 KiB

Open AccessEditorial

Progress in Sustainability and Durability of Concrete and Mortar Composites

by Ofelia Corbu and Ionut-Ovidiu Toma

Coatings 2022, 12(7), 1024; https://doi.org/10.3390/coatings12071024 - 19 Jul 2022

Cited by 4 | Viewed by 1272

The origins of concrete as a construction material date back more than 2000 years ago, but the origins of the term itself are still under debate due to its many different interpretations throughout history [...] Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

Research

Jump to: Editorial, Review

19 pages, 2818 KiB

Open AccessArticle

Research on a Multi-Objective Optimization Design for the Durability of High-Performance Fiber-Reinforced Concrete Based on a Hybrid Algorithm

by Xingyu Wang, Fengkun Cui, Long Cui and Di Jiang

Coatings 2023, 13(12), 2054; https://doi.org/10.3390/coatings13122054 - 07 Dec 2023

Viewed by 703

Abstract

To achieve durable high-performance fiber-reinforced concrete that meets economic requirements, this paper introduces a hybrid intelligent framework based on the Latin hypercube experimental design, response surface methodology (RSM), and the NSGA-III algorithm for optimizing the mix design of high-performance fiber-reinforced concrete. The developed [...] Read more.

To achieve durable high-performance fiber-reinforced concrete that meets economic requirements, this paper introduces a hybrid intelligent framework based on the Latin hypercube experimental design, response surface methodology (RSM), and the NSGA-III algorithm for optimizing the mix design of high-performance fiber-reinforced concrete. The developed framework allows for the prediction of concrete performance and obtains a series of Pareto optimal solutions through multi-objective optimization, ultimately identifying the best mix proportion. The decision variables in this optimization are the proportions of various materials in the concrete mix, with concrete’s frost resistance, chloride ion permeability resistance, and cost as the objectives. The feasibility of this framework was subsequently validated. The results indicate the following: (1) The RSM model exhibits a high level of predictive accuracy, with coefficient of determination (R-squared) values of 0.9657 for concrete frost resistance and 0.9803 for chloride ion permeability resistance. The RSM model can be employed to construct the fitness function for the optimization algorithm, enhancing the efficiency of multi-objective optimization. (2) The NSGA-III algorithm effectively balances durability and cost considerations to determine the optimal mix proportion for the concrete. After multi-objective optimization, the chloride ion permeability resistance and frost resistance of the high-performance fiber-reinforced concrete improved by 38.1% and 6.45%, respectively, compared to the experimental averages, while the cost decreased by 2.53%. The multi-objective optimization method proposed in this paper can be applied to mix design for practical engineering projects, improving the efficiency of concrete mix design. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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12 pages, 5716 KiB

Open AccessArticle

The Effect of Different Particle Sizes of SiO₂ in Sintering on the Formation of Ternesite

by Fengyu Song, Didi Huo, Yanmin Wang, Dunlei Su and Xiaocun Liu

Coatings 2023, 13(11), 1826; https://doi.org/10.3390/coatings13111826 - 25 Oct 2023

Viewed by 810

Abstract

Ternesite is synthesized through sintering a mixture of CaCO₃, SiO₂, and CaSO₄ in a molar ratio of 4:2:1. Ternesite has a hydration rate between ye’elimite and belite in an aluminum-containing environment, and is considered to be a new [...] Read more.

Ternesite is synthesized through sintering a mixture of CaCO₃, SiO₂, and CaSO₄ in a molar ratio of 4:2:1. Ternesite has a hydration rate between ye’elimite and belite in an aluminum-containing environment, and is considered to be a new material that can be used to enhance the performance of calcium sulphoaluminate cements. This experiment investigated the influence of different particle sizes of SiO₂ on ternesite formation. Controlled partial pressure sintering was employed within the temperature range from 1100 °C to 1200 °C, with a 72 h incubation period. The highest purity of ternesite in the samples reached 99.47% (500 nm SiO₂ sample). The analysis results from scanning electron microscopy and an energy dispersive spectrometer indicated that the particle size of SiO₂ exerted a significant influence on the formation of ternesite. In the preparation of ternesite from 10 μm particle size SiO₂, traces of calcium silicate were found in the product. The results of a thermal analysis further demonstrated significant distinctions in the thermal stability of ternesite prepared with SiO₂ of different particle sizes. Additionally, the crystallinity of ternesite was influenced by the particle size of SiO₂, consequently impacting the hydration performance of ternesite–calcium sulphoaluminate cement. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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34 pages, 4414 KiB

Open AccessArticle

Eco-Innovative Concrete for Infrastructure Obtained with Alternative Aggregates and a Supplementary Cementitious Material (SCM)

by Ofelia Corbu, Attila Puskas, Mihai-Liviu Dragomir, Nicolae Har and Ionuț-Ovidiu Toma

Coatings 2023, 13(10), 1710; https://doi.org/10.3390/coatings13101710 - 28 Sep 2023

Cited by 1 | Viewed by 1066

Abstract

Concrete is a heterogeneous material, one of the most widely used materials on the planet, and a major consumer of natural resources. Its carbon emissions are largely due to the extensive use of cement in its composition, which contributes to 7% of global [...] Read more.

Concrete is a heterogeneous material, one of the most widely used materials on the planet, and a major consumer of natural resources. Its carbon emissions are largely due to the extensive use of cement in its composition, which contributes to 7% of global CO₂ emissions. Extraction and processing of aggregates is another source of CO₂ emissions. Many countries have succeeded in moving from a linear economy to a circular economy by partially or fully replacing non-renewable natural materials with alternatives from waste recycling. One such alternative consists of partially replacing cement with supplementary cementitious materials (SCMs) in concrete mixes. Thus, this work is based on the experimental investigation of the fresh and hardened properties of road concrete in which crushed river aggregates were replaced with recycled waste aggregates of uncontaminated concrete. At the same time, partial replacement of cement with a SCM material in the form of glass powder improved the durability characteristics of this sustainable concrete. The microstructure and compositional features of the selected optimum mix have also been investigated using polarized light optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction by the Powder method (PXRD) for the qualitative analysis of crystalline constitutive materials. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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21 pages, 7299 KiB

Open AccessArticle

Study of the Design and Mechanical Properties of the Mix Proportion for Desulfurization Gypsum–Fly Ash Flowable Lightweight Soil

by Xianglong Zuo, Shen Zuo, Jin Li, Ning Hou, Haoyu Zuo and Tiancheng Zhou

Coatings 2023, 13(9), 1591; https://doi.org/10.3390/coatings13091591 - 12 Sep 2023

Viewed by 700

Abstract

In order to solve the global problem of bridge head jumping caused by the insufficient compaction of the roadbed in the transition section of highways and bridges, a desulfurization gypsum–fly ash flowable lightweight soil without vibration, capable of self-compaction, low bulk density, and [...] Read more.

In order to solve the global problem of bridge head jumping caused by the insufficient compaction of the roadbed in the transition section of highways and bridges, a desulfurization gypsum–fly ash flowable lightweight soil without vibration, capable of self-compaction, low bulk density, and economic and environmental protection, has been developed. This study selected low-grade cement, industrial waste (fly ash and desulfurization gypsum), and Yellow River silt as the raw materials for the design of the mix ratio of a desulfurization gypsum–fly ash flow-state lightweight soil mix. Through multiple indoor experiments, the influence of cement content, silt content, and the fly ash/desulfurization gypsum quality ratio on its fluidity and mechanical properties was systematically studied. The stress–strain relationship under uniaxial compression was analyzed and the strength formation mechanism was revealed through scanning electron microscopy (SEM). The results show that the mechanical properties of the prepared desulfurization gypsum–fly ash flowable lightweight soil meet the engineering requirements. Increasing both the cement and fly ash content results in the decreased fluidity of the desulfurization gypsum and fluidized fly ash. However, as the mass ratio of fly ash to desulfurization gypsum increases, the fluidity reaches its maximum when the mass ratio of fly ash to desulfurization gypsum is 2:1. Based on the stress–strain relationship test results, a uniaxial compressive constitutive model of the desulfurization gypsum–fly ash flowable lightweight soil was proposed. The model was fitted and analyzed with the test results, and the correlation was greater than 0.96. The high degree of agreement showed that desulfurization gypsum can promote the disintegration of fly ash, thereby increasing the specific surface area. This provides more contact points, promotes the hardening process, and enhances the interlocking force between particles and the formation of cementitious substances, further enhancing strength. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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27 pages, 19549 KiB

Open AccessArticle

The Advantages on Using GGBS and ACBFS Aggregate to Obtain an Ecological Road Concrete

by Liliana Maria Nicula, Daniela Lucia Manea, Dorina Simedru, Oana Cadar, Ioan Ardelean and Mihai Liviu Dragomir

Coatings 2023, 13(8), 1368; https://doi.org/10.3390/coatings13081368 - 03 Aug 2023

Cited by 1 | Viewed by 729

Abstract

This work aims to show the advantages of using GGBS (Ground Granulated Blast Furnace Slag) and ACBFS aggregate (Air-Cooled Blast Furnace Slag) on the tensile strength and durability properties of infrastructure concrete at the reference age of 28 days. Three concrete mixes were [...] Read more.

This work aims to show the advantages of using GGBS (Ground Granulated Blast Furnace Slag) and ACBFS aggregate (Air-Cooled Blast Furnace Slag) on the tensile strength and durability properties of infrastructure concrete at the reference age of 28 days. Three concrete mixes were prepared: the first one was a control sample; the second one had 15% GGBS (instead of Portland cement) and 25% ACBFS (instead of natural sand); and the third had 15% GGBS (instead of Portland cement) and 50% ACBFS (instead of natural sand). The studies on mortars focused on the ratio of compressive strength (CS) in correlation with the specific surface area (obtained by the Blain method). The microstructure of the prepared mortars was examined at the age of 28 days by X-ray diffraction, SEM electron microscopy with an energy-dispersive EDX spectrometer, and NMR nuclear magnetic resonance relaxometry. The results of the tests carried out afterwards on the concretes containing slag (15% GGBS and 25% or 50% ACBFS) showed values that met high-quality criteria for exfoliation (S₅₆ < 0.1 kg/m²), carbonation, and gelling G100 (with a loss of resistance to compression η < 25%). The slag concretes showed a degree of gelation of G100 (with a loss of compressive strength below 25%), low volume losses below 18,000 mm³/5000 mm² (corresponding to wear class 4, grade I), and moderate penetration of chlorine ions (according to the RCPT test). All of these allow the concrete with slag (GGBS/ACBFS) to be recommended as an ecological road concrete. Our study proved that a high-class road concrete of BcR 5.0 can be obtained, with tensile strengths of a minimum 5 MPa at 28 days (the higher road concrete class in Romania, according to national standards). Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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17 pages, 14593 KiB

Open AccessArticle

Study on the Oil Well Cement-Based Composites to Prevent Corrosion by Carbon Dioxide and Hydrogen Sulfide at High Temperature

by Chunqin Tan, Mu Wang, Rongyao Chen and Fuchang You

Coatings 2023, 13(4), 729; https://doi.org/10.3390/coatings13040729 - 03 Apr 2023

Cited by 3 | Viewed by 1523

Abstract

Complex wells with high temperature and the presence of carbon dioxide and hydrogen sulfide acid gas require the use of high-temperature and high-density anti-corrosion cement slurry for cementing operations, and conventional cement slurry does not have the advantages of high density, high-temperature resistance, [...] Read more.

Complex wells with high temperature and the presence of carbon dioxide and hydrogen sulfide acid gas require the use of high-temperature and high-density anti-corrosion cement slurry for cementing operations, and conventional cement slurry does not have the advantages of high density, high-temperature resistance, or corrosion resistance. In order to avoid the severe corrosion of cement slurry by carbon dioxide and hydrogen sulfide at high temperatures, solid phase particles with different particle sizes are combined with polymer materials to form a dense, high-density, high-temperature- and corrosion-resistant cement slurry. In this paper, we consider the use of manganese ore powder weighting agent, composite high-temperature stabilizer, inorganic preservative slag and organic preservative resin to improve the corrosion resistance of cement slurry, design a high-density cement slurry that is resistant to high temperature and carbon dioxide and hydrogen sulfide corrosion, and evaluate the performances of the cement slurry at 180 °C. The results show that the manganese ore powder weighting agent effectively improves the density of the cement slurry. Using composite silica fume with different particle sizes as a high-temperature stabilizer can ensure the rheology of the cement slurry and improve the ability of the cement sample to resist high-temperature damage. The use of slag and resin as preservatives can effectively reduce the corrosion degree in cement slurry. The high-temperature corrosion-resistant cement slurry systems with different densities designed using these materials exhibit good rheological properties, with water loss of less than 50 mL and a thickening time of more than four hours. The compressive strength decreased by less than 5.8% after 28 days at high temperatures. After being corroded by hydrogen sulfide and carbon dioxide (total pressure 30 MPa, 16.7% hydrogen sulfide and 6.7% carbon dioxide) under high temperature (180 °C) for 30 days, the corrosion depth of the cement sample was less than 2 mm, the reduction of compressive strength was low, and the corrosion resistance was strong. These research results can be used for cementing operations of high-temperature oil and gas wells containing hydrogen sulfide and dioxide. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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14 pages, 21996 KiB

Open AccessArticle

Effect of a New Multi-Walled CNT (MWCNT) Type on the Strength and Elastic Properties of Cement-Based Mortar

by Sergiu-Mihai Alexa-Stratulat, George Stoian, Iulian-Adrian Ghemeş, Ana-Maria Toma, Daniel Covatariu and Ionut-Ovidiu Toma

Coatings 2023, 13(3), 492; https://doi.org/10.3390/coatings13030492 - 23 Feb 2023

Cited by 1 | Viewed by 1290

Abstract

Creating new construction materials with improved strength, elasticity, and durability properties represent the focus of many research works. Significant research effort has been invested in investigating the use of carbon nanotubes (CNTs) in cementitious materials, especially multi-walled carbon nanotubes (MWCNTs) which consist of [...] Read more.

Creating new construction materials with improved strength, elasticity, and durability properties represent the focus of many research works. Significant research effort has been invested in investigating the use of carbon nanotubes (CNTs) in cementitious materials, especially multi-walled carbon nanotubes (MWCNTs) which consist of a series of concentric graphite tubes. The use of MWCNTs is closely related to the use of surfactants and ultra-sonication procedures which may alter their properties and the properties of cement-based materials. The paper presents the preliminary results of an experimental investigation on the suitability of using a new, modified, MWCNT type aimed at eliminating the need of using surfactants and ultrasonication. The modified MWCNTs have a much lower surface energy compared to “classical” ones which would result in a decreased tendency of self-aggregation. A comparison was carried out from the point of view of density, flexural and compressive strength as well as dynamic modulus of elasticity of the obtained mortars. The mortar mix incorporating the modified MWCNTs showed improved mechanical properties even for a low percentage of CNT addition (0.025% by mass of cement). The results are discussed based on the material structure determined from a series of scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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16 pages, 6609 KiB

Open AccessArticle

Experimental Study on the Bending Resistance of Hollow Slab Beams Strengthened with Prestressed Steel Strand Polyurethane Cement Composite

by Jin Li, Yongshu Cui, Dalu Xiong, Zhongmei Lu, Xu Dong, Hongguang Zhang, Fengkun Cui and Tiancheng Zhou

Coatings 2023, 13(2), 458; https://doi.org/10.3390/coatings13020458 - 17 Feb 2023

Cited by 1 | Viewed by 955

Abstract

In order to explore the toughening performance and failure mechanism of hollow slab beams strengthened with prestressed steel strand polyurethane cement composite, three test beams (L1–L3) were strengthened and one test beam (L0) was used as a comparison. The influence of different tensile [...] Read more.

In order to explore the toughening performance and failure mechanism of hollow slab beams strengthened with prestressed steel strand polyurethane cement composite, three test beams (L1–L3) were strengthened and one test beam (L0) was used as a comparison. The influence of different tensile stresses of steel strand and fiber additions on the flexural bearing capacity of the hollow slab beams, was studied. The cracking characteristics, load deflection relationship, ductility and strain of each test beam were compared and analyzed. The test results showed that the toughened material was well bonded to the hollow slab beam and the steel strand, which effectively inhibited the development of cracks in the test beams. The flexural bearing capacity of the strengthened test beams was significantly improved. The use of prestressed steel strand polyurethane cement composite material effectively improved the flexural bearing capacity of the test beams, and this reinforcement process can be further extended to engineering applications. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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21 pages, 4208 KiB

Open AccessArticle

The Influence of Substitution of Fly Ash with Marble Dust or Blast Furnace Slag on the Properties of the Alkali-Activated Geopolymer Paste

by Brăduţ Alexandru Ionescu, Alexandra-Marina Barbu, Adrian-Victor Lăzărescu, Simona Rada, Timea Gabor and Carmen Florean

Coatings 2023, 13(2), 403; https://doi.org/10.3390/coatings13020403 - 10 Feb 2023

Cited by 9 | Viewed by 1746

Abstract

Worldwide, it is now known that industrial by-products rich in silicon (Si) and aluminum (Al) can be transformed by alkaline activation into so-called “green concrete”, an efficient and sustainable material in the field of construction; the geopolymer material. In this work, geopolymer materials [...] Read more.

Worldwide, it is now known that industrial by-products rich in silicon (Si) and aluminum (Al) can be transformed by alkaline activation into so-called “green concrete”, an efficient and sustainable material in the field of construction; the geopolymer material. In this work, geopolymer materials produced using fly ash and marble dust or blast furnace slag were studied to assess the influence of these substitutions on the performances of the final product. Geopolymer materials have been characterized by physico-mechanical methods, FTIR spectroscopy and microscopically. The analysis of the results indicates the reduction of the mechanical strength performance by substituting the fly ash as the raw material. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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14 pages, 2673 KiB

Open AccessArticle

Identification Fluidity Method to Determine Suitability of Weathered and River Sand for Constructions Purposes

by Haoyu Zuo, Jin Li, Li Zhu, Degang Cheng and De Chang

Coatings 2023, 13(2), 327; https://doi.org/10.3390/coatings13020327 - 01 Feb 2023

Cited by 1 | Viewed by 1050

Abstract

At present, in order to comply with the development of the “the Belt and Road Initiatives”, the country is accelerating the pace of construction and increasing the demand for construction river sand. However, the quality of construction river sand is uncontrollable, and its [...] Read more.

At present, in order to comply with the development of the “the Belt and Road Initiatives”, the country is accelerating the pace of construction and increasing the demand for construction river sand. However, the quality of construction river sand is uncontrollable, and its shape is very similar to that of weathered sand. Therefore, using inferior weathered sand and mixed sand as inferior substitute sand in the market is prohibited, resulting in an increase in the difficulty coefficient of quality control of concrete fine aggregate in actual projects. This lays hidden dangers for the construction quality of the project. It is urgent to improve the quality control, testing, and detection process of river sand. Due to the long-term weathering of weathered sand, its density is small, and there are many pores, which leads to the material’s water absorption rate is higher than that of standard sand and river sand during fluidity tests. This paper takes this as a breakthrough point, reveals the variation law of fluidity loss under different variables, and explores a method for effectively screening low-quality sand and gravel. Through the silt content test (screening and washing method), the low-quality sand is preliminarily screened out, the mortar ratio is designed, and the fluidity test is carried out to compare the difference in fluidity loss of different types of mortar; determine the loss threshold range (mobility loss ≤ 15 mm) according to the mobility test results of the control group, and determine the qualification standard by comparing the measured mobility loss of the unknown sample with the loss threshold range. When the mobility loss is within the loss threshold range, the sample is qualified river sand. Otherwise, it is weathered sand or chowder sand. This method establishes a complete detection scheme for distinguishing weathered sand and river sand through mud content tests and mobility loss tests, solves the difficult problem of river sand quality control in engineering applications, and effectively eliminates the phenomenon of using low-quality weathered sand as river sand in the sand and gravel material market, thus avoiding congenital defects in concrete homogeneity. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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17 pages, 1024 KiB

Open AccessArticle

Compressive Strength Estimation of Waste Marble Powder Incorporated Concrete Using Regression Modelling

by Manpreet Singh, Priyankar Choudhary, Anterpreet Kaur Bedi, Saurav Yadav and Rishi Singh Chhabra

Coatings 2023, 13(1), 66; https://doi.org/10.3390/coatings13010066 - 30 Dec 2022

Cited by 2 | Viewed by 1490

Abstract

A tremendous volumetric increase in waste marble powder as industrial waste has recently resulted in high environmental concerns of water, soil and air pollution. In this paper, we exploit the capabilities of machine learning to compressive strength prediction of concrete incorporating waste marble [...] Read more.

A tremendous volumetric increase in waste marble powder as industrial waste has recently resulted in high environmental concerns of water, soil and air pollution. In this paper, we exploit the capabilities of machine learning to compressive strength prediction of concrete incorporating waste marble powder for future use. Experimentation has been carried out using different compositions of waste marble powder in concrete and varying water binder ratios of 0.35, 0.40 and 0.45 for the analysis. Effect of different dosages of superplasticizer has also been considered. In this paper, different regression algorithms to analyse the effect of waste marble powder on concrete, viz., multiple linear regression, K-nearest neighbour, support vector regression, decision tree, random forest, extra trees and gradient boosting, have been exploited and their efficacies have been compared using various statistical metrics. Experiments reveal random forest as the best model for compressive strength prediction with an R2 value of 0.926 and mean absolute error of 1.608. Further, shapley additive explanations and variance inflation factor analysis showcase the capabilities of the best achieved regression model in optimizing the use of marble powder as partial replacement of cement in concrete. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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20 pages, 4329 KiB

Open AccessArticle

Research on the Properties of a New Type of Polyurethane Concrete for Steel Bridge Deck in Seasonally Frozen Areas

by Li Li, Tianlai Yu, Yuxuan Wu, Yifan Wang, Chunming Guo and Jun Li

Coatings 2022, 12(11), 1732; https://doi.org/10.3390/coatings12111732 - 12 Nov 2022

Cited by 1 | Viewed by 1222

Abstract

To widen the application scenarios of polyurethane concrete materials, a new type of polyurethane concrete material for steel bridge deck pavement in seasonally frozen areas was developed, and it was applied to the deck pavement engineering of steel bridges with orthotropic slabs. In [...] Read more.

To widen the application scenarios of polyurethane concrete materials, a new type of polyurethane concrete material for steel bridge deck pavement in seasonally frozen areas was developed, and it was applied to the deck pavement engineering of steel bridges with orthotropic slabs. In this paper, we studied the properties of new polyurethane concrete through the tests of compressive strength, flexural tensile strength, and bond strength with steel plates of polyurethane concrete at different temperatures from −40 °C to 60 °C, totaling 11 temperature levels. We analyzed the elastic modulus, peak strain, and stress–strain relationship curve at the standard temperature. Then, we also conducted SEM test and IR test for the internal destruction form of polyurethane concrete, and analyzed the mechanism of its strength formation. The results show that with increasing temperature, the linear elastic range of polyurethane concrete material is shortened, the elastic modulus, compressive strength, and flexural tensile strength of the material all show a downward trend, and the peak strain and ultimate strain increase significantly. The failure state of the material is gradually transformed from brittle fracture at low temperature to plastic failure at high temperature, and the ductility of the material is significantly improved. Comparing with ones at the standard temperature, the compressive strength at 60 °C is 49.62 MPa downward by 45% and the bending tensile strength of the prism test at 60 °C is 12.34 MPa downward by 51%. Although the stress performance decreases significantly with the change of temperature, it can still meet the strength requirements of the bridge deck pavement for the pavement material. At present, the relevant research is mainly focused on the mechanical properties of new concrete under the influence of high temperature, but research on the mechanical properties of new concrete along with the temperature change is relatively limited. The proposed flexural–tensile constitutive model of polyurethane concrete for steel bridge deck pavement in seasonal freezing areas under the influence of temperature is in good agreement with the experimental results, which can provide a theoretical basis for the application of polyurethane concrete in engineering. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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19 pages, 9013 KiB

Open AccessArticle

Research on Dynamic Stress–Strain Change Rules of Rubber-Particle-Mixed Sand

by Yunkai Zhang, Fei Liu, Yuhan Bao and Haiyan Yuan

Coatings 2022, 12(10), 1470; https://doi.org/10.3390/coatings12101470 - 04 Oct 2022

Cited by 1 | Viewed by 1157

Abstract

We conducted GDS dynamic triaxial tests to study the change rules of the hysteresis curve morphology, axial strain, dynamic elastic modulus, and damping ratio of waste tire rubber-mixed sand-based subgrade model samples with different rubber particle sizes, rubber mixing amounts, and loading times. [...] Read more.

We conducted GDS dynamic triaxial tests to study the change rules of the hysteresis curve morphology, axial strain, dynamic elastic modulus, and damping ratio of waste tire rubber-mixed sand-based subgrade model samples with different rubber particle sizes, rubber mixing amounts, and loading times. The research revealed the developmental rule of the hysteresis curves of waste tire rubber-mixed-sand samples under cyclic loading. From the analyses and comparison of the dynamic stress–strain change rules of rubber-particle-mixed-sand samples under different test conditions, it was concluded that the dynamic elastic modulus and shear stiffness of rubber-mixed-sand samples were smaller than those of pure sand samples under cyclic loading while their damping ratios were greater than that of pure sand samples, promoting vibration resistance and reduction to a larger extent. Therefore, this conclusion is of guiding significance for engineering practice. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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11 pages, 2759 KiB

Open AccessArticle

The Cracking Resistance Behavior of Geosynthetics-Reinforced Asphalt Concrete under Lower Temperatures Using Bending Test

by Qiaoyi Li, Yonghai He, Guangqing Yang, Penghui Su and Biao Li

Coatings 2022, 12(6), 812; https://doi.org/10.3390/coatings12060812 - 10 Jun 2022

Cited by 1 | Viewed by 1287

Abstract

Asphalt is a kind of temperature-sensitive material. With the decrease of temperature, the deformation capacity of an asphalt mixture will be significantly reduced. When the temperature is greatly reduced, the asphalt layer will produce large shrinkage tensile stress and strain, resulting in cracking. [...] Read more.

Asphalt is a kind of temperature-sensitive material. With the decrease of temperature, the deformation capacity of an asphalt mixture will be significantly reduced. When the temperature is greatly reduced, the asphalt layer will produce large shrinkage tensile stress and strain, resulting in cracking. Therefore, the cracking resistance behavior is essential for the asphalt. In order to study the cracking resistance behavior of geosynthetics-reinforced asphalt under lower temperatures, the bending tests were carried out indoors at a temperature of −10 °C. The results showed that compared with the unreinforced asphalt sample, the flexural tensile strength at failure of the geogrid-reinforced sample was increased by 14.1% and 12.3%, corresponding to AC-13C and AC-20C. Additionally, the geotextile-reinforced sample was reduced by 2.5% and 3.6%, corresponding to AC-13C and AC-20C. The values of the bending stiffness modulus of the geogrid- and geotextile-reinforced samples were reduced by 6% and 1%. The cracking energy of the geogrid-reinforced asphalt provides by 45.2% and 30.8% more than unreinforced asphalt, corresponding to AC-13C and AC-20C. The cracking energy of the geotextile-reinforced asphalt is increased by 4.5% and 0.6% compared with unreinforced asphalt, corresponding to AC-13C and AC-20C. The cracking resistance behavior of geogrid-reinforced asphalt is better than unreinforced and geotextile-reinforced asphalt. The asphalt shows obvious brittleness at a temperature of −10 °C, and the existence of the geosynthetics does not change the shape of the load–deflection curves. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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Review

Jump to: Editorial, Research

32 pages, 2263 KiB

Open AccessReview

Use of Clay and Titanium Dioxide Nanoparticles in Mortar and Concrete—A State-of-the-Art Analysis

by Georgiana Bunea, Sergiu-Mihai Alexa-Stratulat, Petru Mihai and Ionuț-Ovidiu Toma

Coatings 2023, 13(3), 506; https://doi.org/10.3390/coatings13030506 - 24 Feb 2023

Cited by 3 | Viewed by 1495

Abstract

In the past decades, nanomaterials have become one of the focal points in civil engineering research. When added to cement-based construction materials (e.g., concrete), it results in significant improvements in their strength and other important properties. However, the final mix characteristics depend on [...] Read more.

In the past decades, nanomaterials have become one of the focal points in civil engineering research. When added to cement-based construction materials (e.g., concrete), it results in significant improvements in their strength and other important properties. However, the final mix characteristics depend on many variables that must be taken into account. As such, there is no general consensus regarding the influence upon the original material of certain nano-sized additives, the optimum dosage or the synergistic effect of two or more nano-materials. This is also the case for titanium dioxide (TiO₂) and nanoclay (NC). The paper focuses on reporting the existing research data on the use of the above-mentioned materials when added to mortar and concrete. The collected data is summarized and presented in terms of strength and durability properties of cement mortar and concrete containing either TiO₂ or NC. Both nano-materials have been proven, by various studies, to increase the strength of the composite, at both room and elevated temperature, when added by themselves in 0.5%~12% for TiO₂ and 0.25%~6% for NC. It can be inferred that a combination of the two with the cementitious matrix can be beneficial and may lead to obtaining a new material with improved strength, elastic and durability properties that can be applied in the construction industry, with implications at the economic, social and environmental levels. Full article

(This article belongs to the Special Issue Recent Progress in Sustainability and Durability of Concrete and Mortar Composites)

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