Materials

Research

15 pages, 5739 KiB

Open AccessArticle

Bond Behavior of FRP Bars in Lightweight SCC under Direct Pull-Out Conditions: Experimental and Numerical Investigation

by Mohammed A. Abed, Zaher Alkurdi, Jan Fořt, Robert Černý and Sandor Solyom

Materials 2022, 15(10), 3555; https://doi.org/10.3390/ma15103555 - 16 May 2022

Cited by 13 | Viewed by 2132

In recent decades, lightweight aggregate concrete (LWC) became a popular building material due to its desired properties. However, various attributes of LWC, such as bond behavior of used reinforcing, have not been described thoroughly. In this regard, LWC produced with 0%, 50%, and [...] Read more.

In recent decades, lightweight aggregate concrete (LWC) became a popular building material due to its desired properties. However, various attributes of LWC, such as bond behavior of used reinforcing, have not been described thoroughly. In this regard, LWC produced with 0%, 50%, and 100% expanded clay aggregate was designed, and the physical–mechanical properties were assessed for material characterization. Subsequently, the bond behaviors of LWC reinforced with steel, glass fiber reinforced polymer (GFRP), and basalt fiber reinforced polymer (BFRP) bars were evaluated by pull-out tests. The results of the experimental program allowed the effects of expanded clay aggregate incorporation on LWC properties to be quantified. The bond strength of BFRP bars was not affected by the replacement of coarse aggregate by expanded clay aggregate, whilst the GFRP bars showed lower bond strength values of LWC specimens. Contrarily, in the case of steel bars, both the bond strength and bond stiffness were higher for LWC specimens than for those of normal concrete. Finite element software ATENA 3D was used for simulation of the bond behavior of LWC, and the model validated by the experimental results referred to reasonably corresponding outputs. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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17 pages, 4414 KiB

Open AccessArticle

Hydrophobic Effect of Soil Stabilization for a Sustainable Subgrade Soil Improvement

by Ali Muftah Abdussalam Ezreig, Mohd Ashraf Mohamad Ismail and Khaled Ibrahim Azarroug Ehwailat

Materials 2022, 15(9), 3087; https://doi.org/10.3390/ma15093087 - 24 Apr 2022

Cited by 5 | Viewed by 1901

Abstract

The chemical process of using additives to stabilize soils is to improve soil that lacks strong engineering properties. In particular, the moisture susceptibility of subgrade soil through seasonal rains is still questionable. The presence of water in the construction is the cause of [...] Read more.

The chemical process of using additives to stabilize soils is to improve soil that lacks strong engineering properties. In particular, the moisture susceptibility of subgrade soil through seasonal rains is still questionable. The presence of water in the construction is the cause of deterioration and premature distress of pavements and their supporting geotechnical structures. In this work, the chemical use of hydrophobic caltite (HC) in various amounts (ranging from 3%, 5%, to 7%) and 5% of cement to enhance laterite soils is investigated. The investigation includes the evaluation of soil properties, such as, unconfined compressive strength (UCS) by curing in air and under water, flexural strength (FS), and California Bearing Ratio (CBR) soaked and unsoaked. The addition of caltite with cement increases the strength characteristics with the UCS values of 2078–2853 kPa during the early curing stages (7th day), and 4688–4876 kPa after 90 days of curing. The added caltite in the cement soil samples shows a reduction index of strength loss underwater with the UCS values of 3196, 3334, and 3751 kPa for caltite cemented soil when compared with cement soil alone. FS results suggest that the inclusion of caltite in cement means that post-peak behavior can be enhanced, reducing the brittleness and increasing the ductility. The successful reaction with soil additives occurred in the curing period of 7 days. In terms of the microstructural analysis, results show that HC with cement reduces the porosity, voids, and cracking of laterite soils. Furthermore, new polymer globules, products from the reaction, appeared on the clay particle surfaces, thereby reducing the water absorption. The addition of hydrophobic-caltite to the soil–cement mixture results in increased strength and reduced water absorption in a soil–cement mix, thus achieving a given strength value. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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20 pages, 7585 KiB

Open AccessArticle

A Numerical Method for Applying Cohesive Stress on Fracture Process Zone in Concrete Using Nonlinear Spring Element

by Zhuheng Li

Materials 2022, 15(3), 1251; https://doi.org/10.3390/ma15031251 - 08 Feb 2022

Cited by 6 | Viewed by 1485

Abstract

Aiming at the numerical simulation of the entire crack propagation process in concrete, a numerical method is proposed, in which cohesive stress on the fracture process zone (FPZ) is simulated and applied by a nonlinear spring element. Using displacement control, the cohesive stress [...] Read more.

Aiming at the numerical simulation of the entire crack propagation process in concrete, a numerical method is proposed, in which cohesive stress on the fracture process zone (FPZ) is simulated and applied by a nonlinear spring element. Using displacement control, the cohesive stress values on the FPZ are obtained from solving a system of nonlinear equations through an iterative process. According to a crack propagation criterion based on initial fracture toughness, the approach adds the spring elements to finite element analysis when simulating mode I crack propagation in standard three-point bending notched concrete beams with different strengths, initial crack ratios

{(a}_{0} / D)

, and depths (D). The simulated load versus displacement (P-Delta) curves are performed to recalculate the fracture energy and verify the accuracy of cohesion in the proposed method. The simulated load versus crack mouth opening displacement (P-CMOD) curves are consistent with the previous experimental results. Subsequently, the variations of the FPZ length and the crack extension resistance (

K_{R})

curves are studied according to the proposed iterative approach. Compared with the existing methods using a noniterative process, the iterative approach generates a larger maximum FPZ length and

K_{R}

curve where the FPZ length is mainly determined by the fracture energy, tensile strength, and geometry shape of the beam, and the

K_{R}

curve is primarily determined by the fracture energy and FPZ length. The significant differences in numerical results indicate that the applying cohesion is essential in numerical simulation. It is reasonable to conclude that the proposed nonlinear spring element is more applicable and practical in the numerical simulation of the concrete mode I crack propagation process by improving the accuracy of the cohesion applied on the FPZ. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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16 pages, 4356 KiB

Open AccessArticle

Utilization of Crushed Pavement Blocks in Concrete: Assessment of Functional Properties and Environmental Impacts

by Václav Kočí, Jan Kočí, Jan Fořt, Lukáš Fiala, Jiří Šál, Izabela Hager and Robert Černý

Materials 2021, 14(23), 7361; https://doi.org/10.3390/ma14237361 - 30 Nov 2021

Cited by 5 | Viewed by 1578

Abstract

Production of concrete is connected to extensive energy demands, greenhouse gases production or primary sources depletion. Reflecting current economical, social, or environmental trends, there is strong pressure on mitigation these requirements and impacts. The exploitation of secondary- or waste materials in production processes [...] Read more.

Production of concrete is connected to extensive energy demands, greenhouse gases production or primary sources depletion. Reflecting current economical, social, or environmental trends, there is strong pressure on mitigation these requirements and impacts. The exploitation of secondary- or waste materials in production processes has therefore a great potential which is not related solely to binders but also to fillers. In this light, this paper aims at thorough investigations of concrete mixtures with crushed concrete pavements as partial or full replacement of natural coarse aggregates. The research combines experimental techniques to quantify the influence of the substitution on basic physical, mechanical, and heat/moisture transport/storage parameters. The experimental data obtained are further exploited as input data for computational prediction of coupled heat and moisture transport to assess the influence of the aggregates substitution on hygrothermal performance of the built-in concretes. In the last step, the environmental impacts are assessed. Since the changes in the hygrothermal performance were found to be insignificant (i), the compressive strength were improved by up to 25% (ii) and most of the environmental impact indicators were decreased (iii) at the same time, the findings of the research presented predeterminate such a reuse strategy to wider application and use. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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16 pages, 21682 KiB

Open AccessArticle

Damage Fracture Characterization of Asphalt Mixtures Considering Freeze–Thaw Cycling and Aging Effects Based on Acoustic Emission Monitoring

by Liuxu Fu, Huanyun Zhou, Jing Yuan, Weiliang An and Xianhua Chen

Materials 2021, 14(20), 5930; https://doi.org/10.3390/ma14205930 - 09 Oct 2021

Cited by 9 | Viewed by 1376

Abstract

Freeze–thaw (F–T) cycling and aging effects are the main factors contributing to the deterioration of asphalt mixtures. The acoustic emission (AE) technique enables real-time detection regarding the evolution of internal damage in asphalt mixtures during the loading process. This study set out to [...] Read more.

Freeze–thaw (F–T) cycling and aging effects are the main factors contributing to the deterioration of asphalt mixtures. The acoustic emission (AE) technique enables real-time detection regarding the evolution of internal damage in asphalt mixtures during the loading process. This study set out to investigate the effects of F–T cycling and aging on the damage characteristics of asphalt mixture under splitting loads. Firstly, the Marshall specimens were prepared and then exposed to various numbers of F–T cycles (one, three, five, and seven) and different durations of aging (short-term aging and long-term aging for 24, 72, 120 and 168 h), after which the specimens were loaded by means of indirect tensile (IDT) testing, and corresponding parameters were synchronously collected by the AE acquisition system during the fracture process. Finally, the energy, cumulative energy and peak frequency were selected to investigate the damage mechanisms of asphalt mixtures. The findings demonstrate that the AE parameters provided effective identification of the deterioration for all specimens in real-time, and that the F–T cycling and aging effects altered the damage characteristics of asphalt mixtures, causing early damage, exacerbating the formation of micro-cracks in the early stage, accelerating the expansion of macro-cracks and advancing the debonding between the asphalt and aggregates. The findings of this study provide further insight into the mechanism of F–T cycling and aging effects on the deterioration of asphalt mixture. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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17 pages, 4183 KiB

Open AccessArticle

Analysis of Basic Physical and Chemical Characteristics of Manganese Slag before and after Solidification and Its Feasibility as Highway Slope

by Meng Chen, Jianming Wei, Runhua Zhang, Lipei Jia, Qiqi Yao and Anchao Han

Materials 2021, 14(19), 5530; https://doi.org/10.3390/ma14195530 - 24 Sep 2021

Cited by 4 | Viewed by 1848

Abstract

Manganese slag is a kind of industrial waste produced by electrolytic production of manganese metal. The traditional method of stacking manganese slag not only causes waste of resources, but also produces environmental pollution. Finding harmless, effective, and economical disposal technology of manganese slag [...] Read more.

Manganese slag is a kind of industrial waste produced by electrolytic production of manganese metal. The traditional method of stacking manganese slag not only causes waste of resources, but also produces environmental pollution. Finding harmless, effective, and economical disposal technology of manganese slag has gradually become a research hotspot and difficulty in the field of electrolytic manganese industry and environmental protection. To verify the feasibility of using manganese slag as roadbed material, the basic physical and chemical properties of manganese slag were analyzed based on X-ray diffraction, X-ray fluorescence spectrum, SEM scanning electron microscope, and particle analysis, the basic engineering characteristics of raw materials of manganese slag and solidified manganese slag mixed with quicklime were analyzed through a compaction test and a CBR test. Finally, based on the Monte Carlo method, the stability of a highway slope in the Guizhou Province of China is simulated by the finite element method, considering the spatial variability of manganese slag material strength parameters. The results show that the solidified manganese slag material can be used as highway subgrade material. This study has important reference significance for manganese slag highway construction projects. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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15 pages, 4115 KiB

Open AccessArticle

Influence of Polypropylene and Steel Fibers on the Performance and Crack Repair of Self-Compacting Concrete

by Mohammed A. Abed, Jan Fořt, Abdulkarim Naoulo and Amr Essa

Materials 2021, 14(19), 5506; https://doi.org/10.3390/ma14195506 - 24 Sep 2021

Cited by 12 | Viewed by 2321

Abstract

The research reported in this paper aims to evaluate the epoxy injection technique used to strengthen fiber-reinforced self-compacting concrete (FRSCC) with high strength. This method is carried out on ruptured concrete specimens to assess the efficiency of the epoxy resin adhesive injection retrofitting [...] Read more.

The research reported in this paper aims to evaluate the epoxy injection technique used to strengthen fiber-reinforced self-compacting concrete (FRSCC) with high strength. This method is carried out on ruptured concrete specimens to assess the efficiency of the epoxy resin adhesive injection retrofitting technique for strength and stiffness. Five FRSCC mixes were designed and placed using different types (steel and polypropylene) and contents (0%, 0.25%, and 0.45% by volume) of fibers. The fresh and mechanical properties in addition to the microstructure of produced mixes were evaluated to assess the impact of fibers on the behavior of FRSCC. Results showed that the workability of FRSCC is reduced by increasing steel or polypropylene fiber content; however, the rheological characteristics of placed mixes satisfied the European Guidelines for Self-Compacting Concrete recommendation for fresh concrete. Also, splitting tensile, flexural, and shear strengths were enhanced by increasing fiber content. The simultaneous application of epoxy injection in FRSCC for repairing damaged concrete beams was shown to be highly effective. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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19 pages, 3396 KiB

Open AccessArticle

Investigation on Preparation and Properties of Crack Sealants Based on CNTs/SBS Composite-Modified Asphalt

by Yafeng Gong, Yunze Pang, Feng He and Haipeng Bi

Materials 2021, 14(16), 4569; https://doi.org/10.3390/ma14164569 - 14 Aug 2021

Cited by 12 | Viewed by 1819

Abstract

Crack is the main distress of asphalt pavement. Sealant is one of the most commonly used crack repair materials, and its performance is the key to affect the service life of asphalt pavements. In order to find an efficient modifier and optimize the [...] Read more.

Crack is the main distress of asphalt pavement. Sealant is one of the most commonly used crack repair materials, and its performance is the key to affect the service life of asphalt pavements. In order to find an efficient modifier and optimize the performances of crack sealants. In this paper, carbon nanotubes (CNTs) and styrene-butadiene-styrene (SBS) were used as modifiers to prepare CNTs/SBS composite-modified asphalt crack sealant. The properties of the sealant were tested to evaluate its suitability for crack repair, which included the viscosity, softening point, resilience recovery, cone penetration, flow value, penetration, aging resistance, and fatigue resistance. The results showed that the conventional properties of the sealants meet the requirements of the specification. In addition, after heating aging, the elastic recovery rate of the sealant containing more CNTs decreased only slightly. The sealant containing 1 wt% CNTs exhibited a higher viscosity, fatigue resistance, thermal aging resistance. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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24 pages, 10539 KiB

Open AccessArticle

Experimental Determination of Mechanical Properties of Waste Tyre Bales Used for Geotechnical Applications

by Aleksander Duda and Tomasz Siwowski

Materials 2021, 14(12), 3310; https://doi.org/10.3390/ma14123310 - 15 Jun 2021

Viewed by 1811

Abstract

Waste tyre-derived products (TDP) are used in some engineering applications and thereby reduce the potential impact on the environment, for example, as lightweight materials in geotechnical engineering projects. One of TDPs is the baling of whole waste tyres to produce rectilinear, lightweight, permeable [...] Read more.

Waste tyre-derived products (TDP) are used in some engineering applications and thereby reduce the potential impact on the environment, for example, as lightweight materials in geotechnical engineering projects. One of TDPs is the baling of whole waste tyres to produce rectilinear, lightweight, permeable bales of high bale-to-bale or bale-to-soil friction. The use of lightweight tyre bales in road construction has the potential to satisfy the demand for low-cost materials exhibiting such a beneficial property. This paper presents a laboratory study on the mechanical properties of tyre bales. The laboratory tests included measurement and evaluation of full-scale tyre bales to determine basic values for the geometry and unit weight, compressibility characteristics of tyre bales, including Young’s modulus and Poisson ratio, shear strength along the tyre–tyre and tyre–soil surfaces, creep and stiffness degradation under cyclic load. The respective test procedures and results of these tests are presented in the paper. The paper provides the mechanical properties of tyre bales required for geotechnical projects, as follows: the unit weight—0.515 Mg/m³, the Young’s modulus—826 kPa, the Poison’s ratio—0.11, the dry tyre–tyre interface: cohesion of 0.03 kPa and friction angle of 46.0°, the wet tyre–soil interface: cohesion 0.77 kPa and a friction angle of 29.6°, creep deformation of 6.1% of the average height of the bale, and no stiffness degradation of tyre bales under cyclic load. These results could be directly applied for the designing and construction of the tyre-baled structures. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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16 pages, 3790 KiB

Open AccessFeature PaperArticle

Effect of Absorptivity of Superabsorbent Polymers on Design of Cement Mortars

by Jan Fořt, Przemysław Migas and Robert Černý

Materials 2020, 13(23), 5503; https://doi.org/10.3390/ma13235503 - 02 Dec 2020

Cited by 10 | Viewed by 2135

Abstract

The functional properties of composites modified by superabsorbent polymers (SAPs) strongly depend on the swelling capacity of applied SAPs. In this sense, three types of commercially available SAPs namely Cablock CT, Hydropam, and Creasorb SIS with different chemical composition and particle size distribution [...] Read more.

The functional properties of composites modified by superabsorbent polymers (SAPs) strongly depend on the swelling capacity of applied SAPs. In this sense, three types of commercially available SAPs namely Cablock CT, Hydropam, and Creasorb SIS with different chemical composition and particle size distribution were studied in this manuscript to reveal the differences in absorptivity as can be viewed as pretests for their utilization in concrete composites. In addition, absorptivity in distilled water, tap water, and 0.1 M NaCl solution are examined for determining the SAPs response for the change of the solution pH. To overcome problems with the teabag method inaccuracy, the new method is introduced. Besides to quantitative evaluation of the SAPs absorptivity, the correlation for the absorption and desorption period as the function of SAPs residence time within the examined solution is proposed. To access the effect of selected SAPs on functional properties, optimization based on the flow table test is employed and mechanical parameters are determined after 7, 14, 28, and 90 days of curing. Obtained results refer to substantial differences between particular SAPs and contribute to the understanding of the effect of SAP on the functional properties of cement-based materials. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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17 pages, 5746 KiB

Open AccessArticle

The Design and Material Characterization of Reclaimed Asphalt Pavement Enriched Concrete for Construction Purposes

by Jaroslav Pokorný, Radek Ševčík and Jiří Šál

Materials 2020, 13(21), 4986; https://doi.org/10.3390/ma13214986 - 05 Nov 2020

Cited by 8 | Viewed by 1907

Abstract

Reclaimed asphalt pavement (RAP) is a valuable commodity originating during processes of road/highways rehabilitations, resurfacing in the cases of the revelation of underneath-placed layers. Removed material can be successfully recycled and utilized as a supplementing material for new hot asphalt mixes. However, its [...] Read more.

Reclaimed asphalt pavement (RAP) is a valuable commodity originating during processes of road/highways rehabilitations, resurfacing in the cases of the revelation of underneath-placed layers. Removed material can be successfully recycled and utilized as a supplementing material for new hot asphalt mixes. However, its dosages are limited because of variations in properties of aged bitumen compared to fresh material and, thus, a significant amount of waste material is remaining as waste products. Nonetheless, this commodity may find usage in the construction industry that suffers from a shortage of high-quality and easily available aggregates. This work aimed to investigate the optimal substitution of mined natural aggregate with commonly available RAP in order to produce composites with the comparable mechanical performance of reference ordinary Portland concrete. The aggregate substitutions up to 100% with RAP have been studied with a combination of mechanical and analytical techniques. Obtained experimental data showed changes in the porous structure, mineralogy, and in the amount of formed cement-related hydration products that influenced the mechanical performance of produced composites. Composite with 10% of natural aggregate substitution with RAP has shown the strength class C16/20 after 28 days of water curing, according to the EN 206-1. Such innovative products could be utilized in the construction industry. The usage of waste RAP could contribute to preservation of our environment for future generations. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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18 pages, 1429 KiB

Open AccessArticle

Construction and Application of Bridge Expansion and Contraction Installation Replacement Decision System Based on the Analytic Hierarchy Process

by Minshui Huang, Zian Xu, Liang Li and Yongzhi Lei

Materials 2020, 13(18), 4177; https://doi.org/10.3390/ma13184177 - 20 Sep 2020

Cited by 4 | Viewed by 3544

Abstract

Bridge expansion and contraction installation (BECI) has proved to be an indispensable component of bridge structures due to its stability, comfort, and durability benefits. At present, conventional replacement technologies for modular-type, comb plate-type, and seamless-type BECIs are widely applied worldwide. However, it is [...] Read more.

Bridge expansion and contraction installation (BECI) has proved to be an indispensable component of bridge structures due to its stability, comfort, and durability benefits. At present, conventional replacement technologies for modular-type, comb plate-type, and seamless-type BECIs are widely applied worldwide. However, it is unfortunate that there remains no systematic research on quantitative assessment approaches for evaluating the overall technical status and selecting optimal replacement methods for existing BECIs. Therefore, considering the installation performance according to functional index evaluations and the economic cost based on life-cycle value assessment (LCVA), a standardized quantitative assessment approach is proposed for optimal replacement method selection in this article. Simultaneously, the other new quantitative assessment method is developed for evaluating the overall technical status of BECIs, which provides a basis for the necessity of replacement. A BECI replacement decision system is constructed, and a corresponding case study illustrates that the proposed system based on the analytic hierarchy process (AHP) in this article proves to be reasonable and feasible. The results reveal that the selected replacement method with both a higher function coefficient and a lower economic coefficient can not only fulfil the performance requirements but also pursue a cost reduction, which leads to a considerable value increment. This system can effectively assist bridge managers in making appropriate operation and maintenance (O and M) decisions in actual engineering projects. Full article

(This article belongs to the Special Issue Material Science in Transportation and Construction Engineering)

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