Large-scale direct shear testing of waste crushed rock reinforced with waste rubber as pavement base/subbase materials

Saberian, Mohammad; Li, Jie; Perera, Salpadoru Tholkamudalige Anupiya. M.; Zhou, Annan; Roychand, Rajeev; Ren, Gang

doi:10.1016/j.trgeo.2021.100546

Cited by 44 publications

(17 citation statements)

References 52 publications

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“…New construction activities also generate concrete and building waste. Therefore, a significant amount of construction and demolition (C&D) waste is generated, and only a small amount is recycled in road bases while the rest goes to landfills [21][22][23][24]. Conversely, in many cities, land areas for C&D wastes disposal are scarce, and the landfill levy to dump these C&D wastes is also increasing every year.…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Recycled Aggregate Concretes Containing Silica Fume and Steel Fibres

et al. 2021

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In this study, the impact of steel fibres and Silica Fume (SF) on the mechanical properties of recycled aggregate concretes made of two different types of Recycled Coarse Aggregates (RCA) sourced from both low- and high-strength concretes were evaluated through conducting 60 compressive strength tests. The RCAs were used as replacement levels of 50% and 100% of Natural Coarse Aggregates (NCA). Hook-end steel fibres and SF were also used in the mixtures at the optimised replacement levels of 1% and 8%, respectively. The results showed that the addition of both types of RCA adversely affected the compressive strength of concrete. However, the incorporation of SF led to compressive strength development in both types of concretes. The most significant improvement in terms of comparable concrete strength and peak strain with ordinary concrete at 28 days was observed in the case of using a combination of steel fibres and SF in both recycled aggregate concretes, especially with RCA sourced from high strength concrete. Although using SF slightly increased the elastic modulus of both recycled aggregate concretes, a substantial improvement in strength was observed due to the reinforcement with steel fibre and the coexistence of steel fibre and SF. Moreover, existing models to predict the elastic modulus of both non-fibrous and fibrous concretes are found to underestimate the elastic modulus values. The incorporation of SF changed the compressive stress-strain curves for both types of RCA. The addition of steel fibre and SF remarkably improved the post-peak ductility of recycled aggregates concretes of both types, with the most significant improvement observed in the case of RCA sourced from a low-strength parent concrete. The existing model to estimate the compressive stress-strain curve for steel fibre-reinforced concrete with natural aggregates was found to reasonably predict the compressive stress-strain behaviour for steel fibres-reinforced concrete with recycled aggregate.

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Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Recycled Aggregate Concretes Containing Silica Fume and Steel Fibres

et al. 2021

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“…For direct shear tests, several standards have been proposed and used in practice. Among them, the ASTM D3080/D3080M-11, hereafter called ASTM, is the most popular and the most used worldwide [2,11,[15][16][17][18][19][20][21][22][23]. It was published as ASTM D3080 in 1972 and updated every eight years by the ASTM technical committees.…”

Section: Introductionmentioning

confidence: 99%

“…This methodology was followed by several researchers [74,75]. However, their direct shear tests were performed by using a W/d max ratio equal to or even smaller than the minimum required value of 10 stipulated by the ASTM standard, exactly the procedure carried out by other researchers [9,16,[19][20][21][22][23]31,58,59,62,63,73,76]. Recently, Deiminiat et al [10] have shown that the minimum required W/d max ratio of 10, stipulated by the ASTM standard, is too small to eliminate SSEs.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Reliability of Scaling Down Techniques Used in Direct Shear Tests to Determine the Shear Strength of Rockfill and Waste Rocks

Deiminiat

2022

CivilEng

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The determination of shear strength parameters for coarse granular materials such as rockfill and waste rocks is challenging due to their oversized particles and the minimum required ratio of 10 between the specimen width (W) and the maximum particle size (dmax) of tested samples for direct shear tests. To overcome this problem, a common practice is to prepare test samples by excluding the oversized particles. This method is called the scalping scaling down technique. Making further modifications on scalped samples to achieve a specific particle size distribution curve (PSDC) leads to other scaling down techniques. Until now, the parallel scaling down technique has been the most popular and most commonly applied, generally because it produces a PSDC parallel and similar to that of field material. Recently, a critical literature review performed by the authors revealed that the methodology used by previous researchers to validate or invalidate the scaling down techniques in estimating the shear strength of field materials is inappropriate. The validity of scaling down techniques remains unknown. In addition, the minimum required W/dmax ratio of 10, stipulated in ASTM D3080/D3080M-11 for direct shear tests, is not large enough to eliminate the specimen size effect (SSE). The authors’ recent experimental study showed that a minimum W/dmax ratio of 60 is necessary to avoid any SSE in direct shear tests. In this study, a series of direct shear tests were performed on samples with different dmax values, prepared by applying scalping and parallel scaling down techniques. All tested specimens had a W/dmax ratio equal to or larger than 60. The test results of the scaled down samples with dmax values smaller than those of field samples were used to establish a predictive equation between the effective internal friction angle (hereafter named “friction angle”) and dmax, which was then used to predict the friction angles of the field samples. Comparisons between the measured and predicted friction angles of field samples demonstrated that the equations based on scalping scaling down technique correctly predicted the friction angles of field samples, whereas the equations based on parallel scaling down technique failed to correctly predict the friction angles of field samples. The scalping down technique has been validated, whereas the parallel scaling down technique has been invalidated by the experimental results presented in this study.

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“…With extensive research spanning the last few decades, researchers have found various applications for increasing the utilisation rate of waste tyres, such as (i) tyre re-treading; (ii) rubber-moulded products like flooring materials and shock absorbing playground mats; (iii) tyre pyrolysis to produce carbon black and oil/gas that can be used as a fuel; (iv) geotechnical applications like sub-grade fill in roads and embankments [1][2][3][4]; (v) rubber modified asphalt pavements [5]; and (vi) in concrete, as a replacement for aggregates [6][7][8][9]. Among all of these applications of tyre recycling, using rubber as a replacement for fine aggregates has been researched extensively in the last few years.…”

Section: Introductionmentioning

confidence: 99%

Practical Rubber Pre-Treatment Approch for Concrete Use—An Experimental Study

et al. 2021

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There is a lot of ongoing active research all over the world looking for various applications of used tyre rubber, to increase its utilisation rate. One of the common research applications is to incorporate rubber into concrete as a partial replacement for conventional aggregates. However, due to its poor bonding performance with cement paste, the utilisation of rubber in concrete has been hindered to date. A cost-effective and time-saving rubber pre-treatment method is of great interest, especially for the concrete industry. Out of all the various pre-treatment methods, soaking rubber particles in water is the most cost-effective and least complex method. In addition, sodium sulphate accelerates the hydration reaction of the cement composites. This study looks at the effect of soaking crumb rubber in tap water for short (2 h) and long (24 h) durations, and the optimised duration was then compared with soaking the crumb rubber in a 5% concentration of sodium sulphate solution. Compressive strength, bond behaviour, and rubber/cement interfacial transition zone (ITZ) were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis. The results demonstrate that a soaking duration of 2 h provides much better performance in both the strength and bond properties compared to 24-h soaking. A further improvement in the 7-day strength was achieved with the rubber soaked in 5% sodium sulphate solution for 2 h, providing a more practical and economical rubber pre-treatment method for concrete industry use.

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Large-scale direct shear testing of waste crushed rock reinforced with waste rubber as pavement base/subbase materials

Cited by 44 publications

References 52 publications

Mechanical Properties of Recycled Aggregate Concretes Containing Silica Fume and Steel Fibres

Mechanical Properties of Recycled Aggregate Concretes Containing Silica Fume and Steel Fibres

Experimental Study on the Reliability of Scaling Down Techniques Used in Direct Shear Tests to Determine the Shear Strength of Rockfill and Waste Rocks

Practical Rubber Pre-Treatment Approch for Concrete Use—An Experimental Study

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