Mechanical Properties Of Rubberized Concrete Research Articles

Uniaxial compressive stress-strain relationship for rubberized concrete with coarse aggregate replacement up to 100%

Rubberized concrete (RuC) is a green and environmentally friendly concrete that can be a sustainable production material by replaced mineral aggregate by rubber particles. Rubber particles used for replacing mineral aggregate classified by two types: shredded or chipped rubber as coarse aggregate and crumb rubber as fine aggregate. Mechanical properties and stress-strain curve of rubberized concrete change as mineral aggregate replaced by rubber particles. However, present constitutive stress-strain models for conventional concrete are not valid for rubberized concrete. Also, proposed modified models for rubberized concrete have been done based on limited experimental tests or low volume replacement ratio for coarse aggregate replacement. Therefore, this paper presents an investigation on the mechanical properties of rubberized concrete with volume replacement of coarse aggregate by rubber particles with size larger than 4 mm up to 100%, which represent about 60–65% from total aggregate, after analyzing published experimental tests in the literature for 98 concrete mixes. New equations were proposed to predict the compressive strength, modulus of elasticity, peak strain and compressive stress-strain relationship with taken the volume replacement of coarse aggregate from total aggregate into account. The proposed equations showed reliable prediction of the mechanical properties and compressive stress-strain relationship of the published experimental tests and improved accuracy over existing models.

Mechanical, Microstructural and Drying Shrinkage Properties of NaOH-Pretreated Crumb Rubber Concrete: RSM-Based Modeling and Optimization.

One of the primary causes of the low mechanical properties of rubberized concrete is the weak bond between crumb rubber (CR) and hardened cement paste. Many CR pretreatment techniques have been researched in an attempt to mitigate this problem. The NaOH pretreatment method is one of the most widely used, although the reported results are inconsistent due to the absence of standardized NaOH pretreatment concentrations and CR replacement levels. This study aims to develop models for predicting the mechanical and shrinkage properties of NaOH-pretreated CR concrete (NaOH-CRC) and conduct multi-objective optimization using response surface methodology (RSM). The RSM generated experimental runs using three levels (0, 5, and 10%) of both NaOH pretreatment concentration and the CR replacement level of fine aggregate by volume as the input factors. At 28 days, the concrete’s compressive, flexural, and tensile strengths (CS, FS, and TS), as well as its drying shrinkage (S), were evaluated as the responses. The results revealed that higher CR replacements led to lower mechanical strengths and higher shrinkage. However, the strength loss and the shrinkage significantly reduced by 22%, 44%, 43%, and 60% for CS, FS, TS, and S, respectively, after the pretreatment. Using field-emission scanning electron microscopy (FESEM), the microstructural investigation indicated a significantly reduced interfacial transition zone (ITZ) with increasing NaOH pretreatment. The developed RSM models were evaluated using ANOVA and found to have high R2 values ranging from 78.7% to 98%. The optimization produced NaOH and CR levels of 10% and 2%, respectively, with high desirability of 71.4%.

Damage Characteristics of Uniaxial Compressed Concrete Embedded Different Aging Rubber by 3D Mesoscale Model

Rapid development of the automobile industry has brought the disposal problem of waste rubber tires. Mixing waste rubber tires into concrete can not only solve environmental problems but also improve the mechanical properties of concrete. Rubber aging is one of the main factors to affect the mechanical properties of rubberized concrete. Therefore, an FEM model of rubberized concrete in mesoscale is established in this paper. The influence of rubber aging on the uniaxial compression damage of rubberized concrete is u;studied. The results show that (1) the elastic modulus and compressive strength of rubberized concrete are negatively correlated with the aging level and content of rubber and positively correlated with the particle size of rubber. (2) After uniaxial compression of concrete enters the softening section, the crack resistance of concrete is positively correlated with the aging level and content of rubber and negatively correlated with the particle size of rubber. (3) Compared with the elastic modulus, the compressive strength of rubberized concrete is more sensitive to the change of parameters of rubber, that is, the change range of the compressive strength of rubberized concrete is always greater than the change range of its elastic modulus, when the aging level, content, and particle size of rubber change.

Experimental Study on the Effect of Freeze–Thaw Cycles on the Apparent and Mechanical Properties of Rubber Concrete Under Chloride Environment

Experimental Study on the Effect of Freeze–Thaw Cycles on the Apparent and Mechanical Properties of Rubber Concrete Under Chloride Environment

Experimental study and failure criterion analysis on combined compression-shear performance of rubber concrete (RC) with different rubber replacement ratio

In order to study the combined compression-shear mechanical properties of rubber concrete (RC), the compression-shear tests of RC under varying axial compression ratios and rubber content were carried out using compression-shear hydraulic servo machine. The shear failure modes and shear load–displacement curves of RC were generated. The characteristics points of load–displacement curves, peak shear strength, residual strength, shear failure displacement, for instance, were also extracted under different loading conditions. The effect of the axial compression ratios and replacement level of rubber particles on the shear mechanical properties of concrete was evaluated. It was reported that shear failure of RC developed slowly while shear failure plane was relatively flat by an increase in axial compression ratio. The friction traces on shear failure plane got more evident when the law of change was not associated to the replacement ratio of rubber particles. Research results also indicated that with successive increase in replacement ratio, the shear strength of concrete gradually decreases while the shear displacement gradually increases. Simultaneously, the increase coefficient of shear load of RC shows a decreasing trend, influenced by the axial compression ratio. The shear strength, residual load and shear displacement were enhanced as the axial compression ratio increased. While the reduction degree of shear load is larger due to the rubber replacement ratio. The cohesion and internal friction angle of concrete decrease by an increase in the rubber replacement ratio while the friction coefficient of the shear failure plane is relatively stable. The failure criterion models of concrete associated with the rubber replacement ratio under combined compression-shear stress are derived from the theory of plane stress space and octahedral stress space. Model results show favorable consistence with experimental data. The manuscript discussed and analyzed the mechanism of concrete under combined compression-shear. The research of this paper is of great significance for scientific research and engineering applications of RC.

Permeation-durability properties of metakaolin blended concrete containing rubber

Numerous works investigating the use of rubber waste as aggregate in concrete have been well documented. Most of the works covered the enhancement method in improving the mechanical properties of rubberized concrete. However, limited works on permeation-durability related characteristics of rubberized concrete have been reported. In this study, further understanding on metakaolin blended concrete containing 10% treated crumb rubber with respect to its permeation-durability behaviour is discovered. The effectiveness of rubberized concrete with the two-stage approach where sodium hydroxide solution treated crumb rubber combined with 15% metakaolin was evaluated on workability, compressive strength, permeation, and durability properties at a different level of superplasticizer (0.25%, 0.50%, 0.75%, and 1.0%). The permeation tests included absorption and permeability whereas rapid chloride permeability and carbonation tests were for durability assessment. The results showed that the reduction in permeation properties and better durability resistance were achieved at a superplasticizer level of 0.75%. Thus, it can be concluded that the good workability of concrete mixture able to discontinued pore connectivity and resulted in high permeation and durability resistance of metakaolin blended-rubberized concrete.

Mechanical properties of rubberized concrete using truck scrap rubber

Concrete is becoming most widely used construction material owing to its versatility and dynamic nature of adopting addition of any admixture into it. Numerous research works were being undertaken by several researchers across the globe to study the inherent nature of concrete with and without various admixtures, replacement agents and chemicals. Usage of natural resource consumption is steadily on raise which is a point to ponder and this is also widely studied in context of concrete generation which is one of the prominent CO 2 emitting industry. Usage of alternate materials in concrete production is a trend gaining impetus, many materials studied in laboratory were being used in field already. This work primarily focusses on production of concrete using crump rubber as an additive material in concrete to increase its toughness and durability. Two different strengths of concrete (M 25 and M 35 ) are studied in this work with varying proportion of rubber added to the concrete. With the results obtained via design of experiments we had added crump rubber from 10 to 30% with reference to the weight batching and conducted experiments in M 35 grade concrete. Strength characteristics such as compressive, tensile (split) and modulus of rupture is calculated which is found to be decreasing with the increasing percentage of crump rubber. This may be the effect of voids created due to the crump rubber addition which can be filled via addition another admixture. Comparing with the control concrete a decrease in strength of about 18%, 39% and 26% is obtained for M 25 grade of concrete concerned with Compressive, Tensile and Flexural strengths, respectively. Concerned with the M 35 grade of concrete the same is found to be at 20%, 47% and 33% for Compressive, Tensile and Flexural strengths respectively comparing to the respective controlled concrete. Hence usage of crump rubber is suggested only at an optimal level above which the strength seems to be reducing.

Experimental Study on the Strengthening Properties of Rubber Concrete with Hook End Steel Fibers

The fast development of automobile sector, removal of discarded waste elastic is turning into a broad ecological problem. In the current work, exertion has been made to limit this problem By using scrap elastic as the scrap (morsel) concrete rubber in various percentages, as a partial replacement for the fine aggregates. In this paper, the mechanical properties of rubberized concrete with steel fibre (RSFC) are studied experimentally. This article discussed the effect by volume of concrete (5, 7.5 and 10 per cent rubber) and (0.8.0.1 and 1.2 per cent steel fibre) on the reinforcement of the properties of rubberized concrete with steel fibres (RSFC) of scrap crumb rubber (SCR) and steel fibre (SF) with different steel substances. The literature survey suggests that there is a substantial decline in strengths of the single morsel rubber used in traditional concrete. like compressive, tensile and flexural strength therefore to overcome this problem by using steel fibers in present investigation and from the results it can be finalized that the all the strengthening properties (compressive, tensile strength and flexural strength) are increased contrasted with rubberized concrete but still test values are inferior than conventional concrete due to fineness of crumb rubber and irregular shape of hook end steel fiber.

Numerical study on blast responses of rubberized concrete slabs using the Karagozian and Case concrete model

Rubberized concrete is a protective structural material with wide prospects for application owing to its superior energy dissipation capacity. In this investigation, to predict the blast responses of rubberized concrete slabs, all parameters in the original Karagozian and Case concrete (KCC) model, which is designated as MAT72REL3 in LS-DYNA, were analysed. Modifications were made to the damage factors and strain rate effect to satisfy the mechanical properties of rubberized concrete. The study verified the feasibility of the modified KCC model through an experimental example to capture the blast responses of rubberized concrete slabs under blast loads. An appropriate erosion criterion corresponding to tensile damage was utilised for normal and rubberized concrete. The numerical results were compared with experimental data from the literature to verify the correctness of the numerical model. A paramedic study was also conducted to investigate the effect of boundary conditions. The results demonstrated that the blast resistance of rubberized concrete is superior to that of normal concrete, regardless of the type of support.

Experimental investigation on bond-slip behavior of selfconsolidating rubberized concrete

Reducing the industry’s impact on the environment is the goal of sustainable construction which can be achieved by using renewable and recyclable resources such as scrap tire waste. Great potential of this waste is found in construction mostly as a partial replacement of mineral aggregate in concrete and mortars, asphalt mixtures and geotechnical works. Previous studies on the selfconsolidating rubberized concrete (SCRC) are mostly concerned with mechanical properties of rubberized concrete. However, in order to allow structural application, it is also necessary to investigate bond-slip behavior of SCRC and reinforcement bars. Thus, in this paper pull-out tests are performed on 24 cubic samples with reinforcement confinement. Three different SCRC mixtures are made, first with concrete without rubber particles as reference mixture, second with 10%, and third with 15% rubber particles and 5% silica fume. The other parameter varied is diameter of steel bars (∅12, ∅16, and ∅20 mm). From the results obtained in experimental investigation, key bond parameters and failure modes of SCRC are compared with bond-slip behavior of self-consolidating concrete (SCC).

Thermal Effect on Bond Strength of Rubberized Concrete Filled Steel Tubular Sections

This study aims to assess the effect of high temperature on the bond strength of Concrete Filled Steel Tubular (CFST) sections incorporating crumb rubber particles as partial replacement of fine aggregates in concrete core. High daily temperatures; as in hot countries; was considered as well. Push out tests were conducted on 72 CFST specimens with five different concrete mixes. Prior to these tests, 210 concrete specimens were tested to obtain the mechanical properties of rubberized concrete under high temperature gradients. Some of the tests; on CFST sections or concrete specimens; were tested at the desired high temperature, and some others were tested after cooling down. The main variables considered were the crumb rubber replacement ratio, type of CFST section (circular or square) and temperature gradient. The test results indicated that high temperature reduces the bond strength between steel tube and rubberized concrete core with small percentage of rubber replacement. Recovery in bond strength was observed when the specimens were cooled down. Circular sections showed higher bond strength and ductility on its square counterpart.

Statistical modeling of rubberized concrete beams confined by FRP using RSM technique

The use of rubber in concrete has been practiced in the engineering community for several years. However, the poor mechanical properties of rubberized concrete are a serious hurdle. This innovative research provides a closer look at improving the flexural strength of rubberized concrete beams with high rubber content using confinement technique. FRP jackets with different confinement thickness were used to recover the strength loss of rubberized concrete beams. In this paper, 66 rubberized concrete (RuC) beams having 0–50% rubber content were tested under four-point loading. RuC beams suffered up to 167% reduction in flexural strength. However, the FRP jackets were highly effective to improve the flexural strength of RuC beams. The statistical models were developed to predict the flexural strength of FRP confined rubberized concrete beams using response surface methodology (RSM). In this regard, the effect of two principle variables; unconfined strength and number of FRP layers on the flexural strength of FRP confined rubberized concrete beams was investigated. The models were found significant because the predicted and adjusted R2 was less than 0.2 (a limit proposed by Design Expert software). The predicted and experimental results for FRP confined rubberized concrete beams were found in good agreement. The developed statistical models provide insights into the sensitivity of parameters affecting the flexural strength. The proposed models can improve the reliability of the experiments and reduces the design and analysis time.

Experimental Investigation on the Freeze-Thaw Resistance of Steel Fibers Reinforced Rubber Concrete.

The reuse of rubber in concrete results in two major opposing effects: an enhancement in durability and a reduction in mechanical strength. In order to strengthen the mechanical properties of rubber concrete, steel fibers were added in this research. The compressive strength, the four-point bending strength, the mass loss rate, and the relative dynamic elastic modulus of steel fiber reinforced rubber concrete, subjected to cyclic freezing and thawing, were tested. The effects of the content of steel fibers on the freeze–thaw resistance are discussed. The microstructure damage was captured and analyzed by Industrial Computed Tomography (ICT) scanning. Results show that the addition of 2.0% steel fibers can increase the compressive strength of rubber concrete by 26.6% if there is no freeze–thaw effect, but the strengthening effect disappears when subjected to cyclic freeze–thaw. The enhancement of steel fibers on the four-point bending strength is effective under cyclic freeze–thaw. The effect of steel fibers is positive on the mass loss rate but negative on the relative dynamic elastic modulus.

Experimental Research on Chloride Erosion Resistance of Rubber Concrete

Chloride corrosion test was carried out in 4% NaCl solution to study the chloride corrosion resistance of rubber concrete. Rubber concrete was prepared by using 20 mesh, 1∼3 mm, and 3∼6 mm rubber particles instead of sand by 5%, 10%, 15%, and 20% of the cementitious material mass. The P‐wave velocity and compressive strength of rubber concrete were measured. The microstructure of rubber concrete corroded by chloride was analyzed by SEM. The micromorphology was compared with the macrofailure characteristics under uniaxial compression. The results show that the rubber concrete was still in the early stage of erosion. With the increase of immersion time at the age of 110 days, the P‐wave velocity and compressive strength of concrete were generally on the rise. Furthermore, during the period of erosion, the mechanical properties of rubber concrete increased with the increase of rubber particle size and decreased with the increase of the content. Therefore, when the rubber particle size was 3∼6 mm and the content was 5%, the antierosion performance was the best. This study has a certain guiding significance for the chloride corrosion resistance of rubber concrete.

Determination of Mechanical Properties of Rubberized Concrete in Marine Environment

With an objective of saving the environment by providing crumb rubber as an alternative to natural fine aggregate this paper presents a study carried out to find the mechanical properties of rubberized concrete. Rubberized concrete is made up of waste rubber from vehicle tyres and other rubber waste which otherwise is left out polluting the environment. In this paper, 7.5% of crumb rubber (obtained by shredding the vehicle tyres) as an alternative to fine aggregate and 7.5% of fly-ash as an alternative to cement is added with other ingredients of concrete to produce an eco-friendly concrete which can be used economically and effectively for construction along the coastal areas. Various properties like workability, compressive strength, split tensile strength, and flexural strength was carried out on concrete specimens exposed to the natural marine environment along the coast of Visakhapatnam, Andhra Pradesh. The total exposure of concrete specimen was about 150 days, and various specimens were tested at 7, 28, 90, 120 and 150 days, respectively. The test results showed that with a slight compromise in strength, the workability of concrete and resistance to the effect of seawater on the strength of concrete significantly improved with the addition of crumb rubber and fly-ash.

Investigation on the interfacial behaviour between the rubber-cement matrix of the rubberized concrete

Rubberized concrete is an innovative clean production material. In this study, the interfacial behaviour of the rubber-cement matrix (R-CM) of rubberized concrete was improved by selecting better rubber types, surface modifiers, mixing methods, supplementary cementing materials (SCMs), water-binder ratio (W/B ratio), and mixing time. The slump, apparent density, compressive strength, impact strength, and R-CM interfacial bonding property of the rubberized concrete were determined. The results showed that the following combination delivered an improved rubberized concrete (IRC) with the best R-CM interfacial bond strength – acrylonitrile-butadiene rubber (NBR), W/B ratio of 0.42, mixing time of 150 s, styrene-butadiene latex (SBL) as a surface modifier and a SCM, premixing rubber and binder paste. The main factors affecting the R-CM interfacial bonding properties were the rubber type, surface modifier, mixing method, and W/B ratio. Compared to the reference rubberized concrete, the R-CM interfacial tensile bond strength, shear bond strength, compressive strength, and impact strength of IRC increased by 756%, 151%, 48.1%, and 17%, respectively. As a surface modifier, SBL provided a connection between NBR and the binder paste, while as a SCM, it created an environment for reducing the W/B ratio of rubberized concrete. The R-CM interface was found to play a major role in controlling the macro mechanical properties of rubberized concrete.

Effects of Rubber Particles on Rheological and Mechanical Properties of Concrete Containing CaCO3 Nanoparticles

Lots of waste rubber is being produced in the world and the utilization of it not only mitigate environmental impacts caused by waste rubber disposal but also enhance sustainable development. As a result, rubberized concrete, by incorporation of waste rubber into concrete, should be considered as one of the effective strategies to take advantage of waste rubber. However, problems such as low strengths, weak adhesion between rubber particles and cement pastes, and undesirable pore structures associated with rubberized concrete should be pay more attention to. In this study, the effect of replacement fine aggregate with rubber particles on rheological and mechanical properties of concrete containing CaCO3 nanoparticles was examined through slump, compressive and flexural strength tests. Rubber particles were employed to replace the fine aggregate equally by volume while CaCO3 nanoparticles were used as an equal part of binder by weight. Different sizes and volume contents of rubber particles were evaluated as well as different weight contents of CaCO3 nanoparticles. In addition, corresponding tests were also performed to evaluate the effect of CaCO3 nanoparticles in comparison to concrete specimens without CaCO3 nanoparticles. The results showed that replacement fine aggregates with rubber particles had some influence on the mechanical properties of rubberized concrete, resulting in undesirable findings in terms of compressive and flexural strengths. However, the incorporation of CaCO3 nanoparticles improved mechanical properties of rubberized concrete. Regarding slump test, the rubberized concrete without CaCO3 nanoparticles showed better performance. Considering rheological and mechanical properties, rubberized concrete with 1% CaCO3 nanoparticles presented acceptable results.

Ponašanje pri zamoru uslijed savijanja i mehanička svojstva betona s dodatkom gumenog granulata

Ponašanje pri zamoru uslijed savijanja i mehanička svojstva betona s dodatkom gumenog granulata

THE IMPACT OF RUBBER CRUMB ON THE MECHANICAL AND CHEMICAL PROPERTIES OF CONCRETE

Various works have been carried out on both the physical and mechanical properties of rubberized concrete in previous research. But the chemical composition of rubberized concrete has not been fully investigated. The scanning electron microscopy (SEM) and energy-dispersive x-ray spectrum (EDX) analysis were used to determine the element composition and the peak intensity of chemical elements in the waste rubber concrete. The SEM and EDX analysis results showed that, ferrous iron, oxygen, calcium, and silicon were the dominant elements, and these elements reduced as more waste rubber were added to the concrete. Carbon and sulphur elements increased as rubber crumbs were added to the rubberized concrete. The work concluded that the presence of rubber crumb in the concrete samples contributed to both mechanical and chemical changes in the property of rubberized concrete.

Mechanical properties of rubberised concrete for road side barriers

This paper presents the mechanical properties of rubberized concrete for roadside barriers with the intent to reduce injuries and fatalities during crashes. The test programme involved the preparation of normal strength concretes made out of recycled waste tire rubber. The tire–rubber particles composed of a combination of crumb rubber and fine rubber powder were used to replace 10, 20, 30 and 40% of the total weight of the fine aggregate. The test results indicated considerable reductions in compressive and flexural strengths, and tangential modulus of elasticity. New design guidelines in accordance with the Australian Bridge Design Code AS 5100 for strength and serviceability of rubberized concrete roadside barriers were derived based on the test results. New moment-thrust interaction curves and shear strength equations were derived for the rubberized concrete. It was found that the shear strength is critical compared to the combined moment and axial thrust and the maximum rubber content was 17% max for rubberized concrete.