Self-consolidating Rubberized Concrete Research Articles

Bond-slip behavior of self-consolidating rubberized concrete

• Study of the bond-slip behavior in self-consolidating rubberized concrete (SCRC) • Overview of the available studies on bond-slip behavior in SCRC. • Results show, the bond strength depends on the diameter of reinforcement bar and rubber content. • Proposition of the analytical model for predicting bond strength and corresponding slip. • Ultimate bond strength as a function of the reinforcement diameter, compressive strength and rubber content. A sustainable solution was found for the use of waste material such as used tires by partially replacing the natural aggregate in the concrete with recycled rubber particles. This resulted in improved ductility, but at the expense of reduced strength and stiffness. To further investigate the behavior of rubberized concrete, this paper investigates the bond-slip behavior of reinforcement in self-consolidating rubberized concrete. A total of 27 cubic specimens with reinforcement bars and embedded confinement were constructed. Two parameters affecting the bond-slip behavior were investigated: the reinforcement bar diameter (∅12, ∅16, ∅20 mm), the content of rubber particles in the self-consolidating concrete (0%, 10%, 15%), and silica fume (0%, 5%). From the experimental results, it can be concluded that both a higher rubber content and a larger reinforcement diameter have a negative effect on the bond coefficient, reducing it by up to 28.87% and 18.78%, respectively, while the bond strength decreases by 33% for a rubber replacement of 15%. In the case of rubberized concrete, a more ductile behavior is observed due to the rubber content. Based on the obtained results, a parametric analysis was performed and an analytical prediction model was proposed.

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).

Influence of synthetic fibers’ type, length, and volume on enhancing the structural performance of rubberized concrete

This study aimed to investigate the influence of using different synthetic fibers’ (SFs) type, length, and volume on enhancing the structural performance of rubberized concrete beams. Different self-consolidating rubberized concrete (SCRC) and vibrated rubberized concrete (VRC) with different percentages of crumb rubber (CR) and SFs were tested. The main parameters were the percentage of CR (0%, 10%, 15%, 20%, and 30% by volume of sand), type of SFs (micro-synthetic fibers (MISFs) and macro-synthetic fibers (MASFs)), length of SFs (19 mm, 38 mm, 50 mm, 54 mm), and volume of SFs (0%, 0.2%, and 1%). The structural performance of the tested beams was assessed based on the characteristics of load-deflection curves, flexural stiffness, cracking behavior, displacement ductility, energy absorption, cracking moment, and bending moment capacity. The results indicated that using MISFs slightly enhanced the deformability, flexural stiffness, ductility, energy absorption, cracking moment, and bending moment capacity, while this enhancement significantly increased when MASFs were used. The results also showed that increasing the MASF length from 38 mm to 50 mm exhibited less improvement in the structural performance of rubberized beams. Meanwhile, MASF54 (MASF with 54 mm length) showed better improvement compared to MASF50 (MASF with 50 mm length) but still less than MASF38 (MASF with 38 mm length). Combining high percentage of MASF38 (1%) with high percentage of CR (30%) compensated for the reduction in the bending moment capacity (that resulted from using high percentage of CR) and helped to develop semi-lightweight concrete beams.

Classification of damage in self-consolidating rubberized concrete using acoustic emission intensity analysis

This article presents the results from an experimental study on the application of acoustic emission (AE) analysis to assess the damage progression of self-consolidating rubberized concrete (SCRC) mixtures under four-point flexural tests. Self-consolidating concrete (SCC) mixtures incorporating four variable replacements of crumb rubber (CR) including 0, 10, 20, and 30% were examined to study the effect of CR content on the AE damage detection and quantification capability. Normal concrete (NC) and normal rubberized concrete (NRC) mixtures, with 0 and 40% CR respectively, were also tested for the comparison. Two prism samples were tested from each mixture under monotonic loading conditions, while being constantly monitored via two attached AE sensors until failure. The acoustic emissions obtained from these sensors were related to the damage evolution of the tested prisms from all mixtures. The effects of variable mixture types and CR content on different AE parameters were highlighted. The considered AE parameters included signal characteristics (in terms of signal amplitude) as well as number of AE hits and cumulative signal strength (CSS). In addition, AE b-value and intensity analyses were further performed on the amplitude and signal strength of all AE signals to evaluate the extent of damage by means of three additional AE parameters including b-value, historic index, H (t), and severity, Sr. The outcomes of the AE analysis indicated the usefulness of the considered AE parameters in the detection of two early damage stages including micro- and macro-cracking before failure, irrespective of the CR content. Eventually, the intensity analysis parameters (H (t) and Sr) were correlated to the stages of micro- and macro-cracking in all mixtures for the purpose of damage classification via developed chart.

Evaluation of Abrasion Resistance of Self-Consolidating Rubberized Concrete by Acoustic Emission Analysis

AbstractThe purpose of this study was to investigate and compare the abrasion resistance of self-consolidating concrete (SCC) with crumb rubber (CR) in conjunction with acoustic emission (AE) monit...

The combined effect of crumb rubber and synthetic fibers on impact resistance of self-consolidating concrete

This study was conducted to evaluate the impact resistance and mechanical properties of self-consolidating rubberized concrete (SCRC) mixtures reinforced with synthetic fibers (SFs). In particular, the investigation aimed to maximize the impact resistance and energy absorption of SCRC mixtures by optimizing the mixture proportions and by using the most appropriate types and volumes of SFs. The study also presented the effect of steel fibers (SLFs) on the impact resistance and mechanical properties of SCRC for comparison. The tested fibers consisted of three types of flexible SFs (19-mm, 38-mm, and 50-mm), two types of semi-rigid SFs (27-mm and 54-mm), and two types of hooked-end SLFs (35-mm and 60-mm). The results indicated that increasing the CR content had a negative effect on the mechanical properties of SCRC mixtures, while the ductility and impact resistance were significantly improved. Using SFs in SCRC mixtures further increased the impact resistance and appeared to alleviate the reduction in splitting tensile strength (STS) and flexural strength (FS) that resulted from adding CR. Although using longer SFs had a negative impact on the fresh properties of SCRC, it greatly improved the mechanical properties and impact resistance of the mixtures. The results also indicated that in the absence of the challenge of achieving self-compactibility, it was possible to develop vibrated rubberized concrete with higher percentages of CR and SFs, which in turn resulted in higher improvements in STS, FS, impact resistance, and further reduction in the self-weight of concrete.

Development of self-consolidating rubberized concrete incorporating silica fume

This investigation was carried out to evaluate the effect of using silica fume on the development and optimization of self-consolidating rubberized concrete (SCRC). In particular, the investigation aimed to optimize successful silica fume self-consolidating rubberized concrete (SLFSCRC) mixtures with maximized percentage of crumb rubber (CR) (as a partial replacement of fine aggregate) and minimized strength reduction. The study also compared the behaviour of silica fume (SLF) with other supplementary cementitious materials (SCMs) in optimized SCRC mixtures. The results indicated that the use of SLF helped to develop SCRC mixtures with improved strength and acceptable fresh properties with up to 25% CR. Using SLF or metakaolin (MK) in SCRC exhibited superior behaviour among other SCMs in terms of strength. However, using SLF in SCRC showed better mixture flowability and less dosage of high range of water reducer admixture compared to using MK in SCRC. It was also noticed that adding steel fibres (SFs) to SLFSCRC mixtures greatly enhanced the mechanical properties, especially the splitting tensile strength and flexural strength. The results also showed that since there is no challenge to achieving acceptable self-compactibility (especially passing ability) in vibrated rubberized concrete, it was possible to develop silica fume vibrated rubberized concrete (SLFVRC) with higher percentages of CR and SFs and with further improved flexural and tensile strengths.

Impact Resistance and Acoustic Absorption Capacity of Self-Consolidating Rubberized Concrete

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Impact Resistance and Mechanical Properties of Self-Consolidating Rubberized Concrete Reinforced with Steel Fibers

This study evaluates the impact resistance and mechanical properties of a number of developed self-consolidating rubberized concrete (SCRC) mixtures reinforced with steel fibers (SFs). In this research, SFs were used to compensate for the reduction in tensile and flexural strength that resulted from adding high volumes of crumb rubber (CR). SFs were also used to exploit the beneficial interaction between SFs and CR to develop low-density concrete with higher impact resistance. The experimental variables were different replacement levels of fine aggregate volume by CR (0–40%), binder content (550–600 kg/m3), SF volume fractions (0, 0.35, 0.5, 0.75, and 1%), and size of SFs. Tests included fresh properties, compressive strength, splitting tensile strength (STS), flexural strength (FS), and impact loading (drop-weight on cylindrical specimens and flexural impact loading on small-scale beams). The results indicated that adding CR to concrete improved the impact energy absorption and ductility, whereas the mechanical properties decreased as the percentage of CR increased. Using SFs can greatly increase the impact resistance of SCRC and compensate for the reduction in STS and FS that resulted from the addition of CR. However, the high blockage in the L-box test limited the possible combination of SFs and CR in SCRC mixtures. Since passing ability was not a factor in the development of vibrated rubberized concrete (VRC), it was possible to combine higher volumes of CR and SFs safely in VRC, achieving more reductions in self-weight and improvements in the STS, FS, ductility, and impact resistance.

Ductility and Cracking Behavior of Reinforced Self-Consolidating Rubberized Concrete Beams

This paper investigates the applicability of using optimized self-consolidating rubberized concrete (SCRC) and vibrated rubberized concrete (VRC) mixtures in structural applications. The curvature ductility, ultimate flexural strength, and cracking characteristics of different SCRC and VRC mixtures were tested using large-scale reinforced concrete beams. The variables were crumb rubber (CR) percentage (0–50% by volume of sand), different binder contents (500–550 kg/m3), inclusion of metakaolin (MK), use of air entrainment, and concrete type. The performance of some design codes were evaluated in predicting the cracking moment and crack widths of the tested beams. The results indicated that although the flexural capacity of the tested beams decreased with the addition of CR, adding CR improved the beams’ curvature ductility and reduced its self-weight. Adding CR into concrete also appeared to limit the flexural crack widths but with a slightly higher number of cracks compared to beams without CR. In general, the obtained results from the present work indicate promising potential for SCRC and VRC use in structural applications.

Use of metakaolin on enhancing the mechanical properties of self-consolidating concrete containing high percentages of crumb rubber

This research aimed to investigate the mechanical properties of self-consolidating rubberized concrete (SCRC) mixtures with high percentages of crumb rubber (CR). The effect of metakaolin (MK) compared to other supplementary cementing materials (SCMs) on enhancing the mechanical properties and stability of SCRC mixtures was highlighted in this research. The variables were percentage of CR (0–50% by volume of sand), type of SCM (fly ash, slag, and metakaolin), binder content (500–550 kg/m3), coarse aggregate size (10–20 mm), and air entrainment. The mechanical properties of the tested mixtures were investigated based on their compressive strength, flexural strength, splitting tensile strength, and modulus of elasticity. The results indicated that using MK improved the mixture stability and particle suspension, which facilitated the development of SCRC mixtures with a high percentage of CR (30%) and with enhanced mechanical properties. Adding entrained air to SCRC mixtures with MK further enhanced the fresh properties and stability, and allowed a higher percentage of CR (40%) to be used safely in SCRC with acceptable stability/strength and with a density of less than 2100 kg/m3. The results also indicated that although SCRC mixtures had slightly higher mechanical properties compared to vibrated rubberized concrete (VRC), the problems associated with the fresh properties and stability of SCRC mixtures were reduced in VRC, which allowed up to 50% CR to be used in this mixture with acceptable stability/strength and with further reduction of the mixture density (less than 2050 kg/m3).

Performance of Full-Scale Self-Consolidating Rubberized Concrete Beams in Flexure

This research investigated the performance of full-scale self-consolidating rubberized concrete (SCRC) and vibrated rubberized concrete (VRC) beams in flexure. The beam mixtures were developed with a maximum possible percentage of crumb rubber (CR) (0 to 50% by volume of sand) while maintaining acceptable fresh properties and minimum strength reduction. The mixture variables included different binder contents, the addition of metakaolin, and the use of air entrainment. The performance of the tested beams was evaluated based on load-deflection response, concrete strain/stiffness, cracking behavior, first crack load, ultimate load, ductility, and toughness. In general, increasing the CR content decreased the mechanical properties, first crack load, stiffness, and self-weight of all SCRC and VRC beams. However, using up to 10% CR enhanced the deformation capacity, ductility, and toughness of tested beams without affecting the flexural capacity. This improvement in the deformation capacity, ductility, and toughness appeared to continue up to 20% CR (but with a slight reduction of the flexural capacity) and then reduced with further increases in the CR content. The results also indicated that although it was possible to produce VRC beams with higher percentages of CR (50% compared to 40% in SCRC), this increased percentage only gave VRC beams an advantage in terms of self-weight reduction, while it had a limited contribution in enhancing the structural performance of the beams.

A study on dynamic modulus of self-consolidating rubberized concrete

In this study, dynamic modulus of elasticity of self-consolidating rubberized concrete is evaluated by using results of ultrasonic pulse velocity and resonance frequency tests. Additionally, correlation between dynamic modulus of elasticity and compressive strength results is compared. For evaluating the dynamic modulus of elasticity of self-consolidating rubberized concrete, prismatic specimens having <TEX>$100{\times}100{\times}500$</TEX> mm dimensions are prepared. Dynamic modulus of elasticity values obtained by non-destructive measurements techniques are well agreed with those given in the literature.

Influence of Mixture Composition and Type of Cementitious Materials on Enhancing the Fresh Properties and Stability of Self-Consolidating Rubberized Concrete

An experimental investigation was conducted to study the development of self-consolidating rubberized concrete (SCRC) with improved flowability, passing ability, stability, and strength for multiple structural applications. The investigation particularly aimed to maximize the percentage of used crumb rubber (CR) in SCRC while minimizing the reduction in strength and stability of the developed mixtures. The experimental test parameters included CR percentage (0–50% by volume of sand), binder content (500–550 kg/m3), coarse aggregate size (10–20 mm), air entrainment, and supplementary cementing material (SCM) (fly ash, ground granulated blast-furnace slag, and metakaolin). The performance of the developed SCRC was evaluated based on the results for compressive strength, flowability, passing ability, high-range water-reducer admixture (HRWRA) demand, coarse aggregate segregation, and CR distribution. The results indicated that mixtures with 500 kg/m3 binder content had acceptable strength, fresh properties, and stability with up to 15% CR replacement. Using 550-kg/m3 binder content improved SCRC mixture stability and allowed up to 20% CR to be used safely. Compared with the other tested SCMs, metakaolin (MK) significantly improved mixture viscosity and particle suspension/distribution, which allowed the use of up to 30% CR in SCRC mixtures. The results also showed that, despite the reduction in compressive strength in mixtures with entrained air, using air entrainment in SCRC with MK further improved the fresh properties of these mixtures and allowed up to 40% CR to be used with acceptable compressive strength (25.7 MPa) and with no sign of segregation.

Fresh, Mechanical, Transport, and Durability Properties of Self-Consolidating Rubberized Concrete

Fresh, Mechanical, Transport, and Durability Properties of Self-Consolidating Rubberized Concrete