The Experts below are selected from a list of 327 Experts worldwide ranked by ideXlab platform
Anaclet Turatsinze - One of the best experts on this subject based on the ideXlab platform.
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Effect of Styrene-Butadiene Copolymer Coating on Properties of Rubberized Cement-Based Composites
Strain-Hardening Cement-Based Composites, 2017Co-Authors: Ngoc Phuong Pham, Ahmed Toumi, Anaclet TuratsinzeAbstract:Properties of improved strain capacity and high shrinkage cracking resistance make Rubberized cement-based composites suitable for large surface applications such as pavements and thin bonded cement-based overlays. Microstructurally, the interfacial transition zone (ITZ) between Rubber Aggregate and cementitious matrix is different from that encountered with conventional Aggregates. It is universally accepted a reduction in mechanical properties due to the low stiffness of Rubber Aggregates. However, transport properties are possible to be improved and comparative with conventional concrete or mortar if bonds between Rubber particle and cementitious matrix were induced by pre-coating Rubber Aggregates to become hydrophilic and preventing air-entrapment phenomenon’s during mixing and placing composites. In this study, two distinct solutions were suggested to improve properties of composites such as using air-detraining admixture and styrene-butadiene copolymer as agent for Rubber Aggregate coating. Rubber particles with sizes 0–4 mm were incorporated in mortar as 30% sand replacement by volume. Microstructural analysis by Scanning Electron Microscopy (SEM) clarified the dense interface due to bonds generated by coagulation of the cement paste-polymer on the Rubber surface. The initial experimental results showed a reduction in air permeability of composites modified with styrene-butadiene copolymer. As expected, this treatment method also contributed positively to mechanical properties of composites, especially direct tensile strength.
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Effects of Rubber Aggregates from grinded used tyres on the concrete resistance to cracking
Journal of Cleaner Production, 2012Co-Authors: Anaclet Turatsinze, Rashid HameedAbstract:In practice, pavements or slabs are subjected to wide range of length changes during their service life. In case of cement-based materials, their length changes due to shrinkage and/or temperature variations induce tensile stress which can result in cracking detrimental for durability. Generally, aggravating circumstances are observed due to the length change restraint. This contribution focuses on experimental results of tests performed on Rubberized concrete produced by partly replacing natural sand (0–4 mm) by Rubber Aggregates up to 40% by volume. The Rubber Aggregates are obtained by grinding of used tyres. Effect of Rubber Aggregate on brittleness index (BI) and on damage evolution was investigated by conducting three-point bending tests on notched beam. Results of these tests confirmed that the both BI and damage decrease with the increase of Rubber Aggregate content in the concrete. Acoustic emission (AE) technique was applied to detect damage mechanism in concrete by analyzing AE parameters. The Elastic Quality Index (EQI) was adopted to take into account two mutually exclusive properties which govern the sensitivity to cracking, namely strain capacity and tensile strength. Results obtained from the tests performed at 20 °C, 40 °C and 70 °C showed that Rubberized concrete exhibits EQI values within acceptable limits for the design of cement-based pavements.
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Mechanical properties of steel fibre reinforced and Rubberised cement-based mortars
Materials & Design, 2010Co-Authors: T.-h. Nguyen, Ahmed Toumi, Anaclet TuratsinzeAbstract:Previous studies demonstrated that crack cutting bonded cement-based repairs is highly detrimental to the durability of such applications. Laboratory tests and field experience showed that fibre reinforcement allowing the control of the crack opening and assuring the structural continuity is a solution to enhance the durability of bonded cement-based repairs. In other respect, recent work pointed out that the use of Rubber Aggregates obtained from grinding end-of-life tyres is a suitable solution to improve the strain capacity of cement-based materials. The present contribution focuses on the synergetic effect of Rubber Aggregate incorporation and of fibre reinforcement from the point of view of the use of the composite in the repair work application. Effects of fibre reinforcement, of Rubber Aggregates incorporation and of their association are evaluated by comparing the mechanical response of the cementitious mortars in which they are used to the one of the control mortar. Fibre reinforced and/or Rubberised cement-based mortar were cast using 20% and 30% by volume of Rubber Aggregates replacing mineral Aggregates. To control the crack as soon as possible, a type of high bond steel fibre was selected in this study and contents of 20, 30, 40kg/m3 have been used. Direct tensile tests were firstly conducted to obtain the tensile strength, the straining capacity and the residual post peak behaviour. Compressive strength and Young’s modulus were determined from compressive tests. Results showed that despite Rubber incorporation was detrimental to the material strength (compressive and tensile strengths) and reduced the modulus of elasticity, the strain capacity was enhanced. Results obtained on steel fibre reinforced and Rubberised cement-based mortars (SFRRM) pointed out a positive synergetic effect: it is noted that one can make profitable the effects of Rubber Aggregates (high strain capacity) and those resulting from the fibre reinforcement (significant residual post peak strength) to get an interesting behaviour when resistance to cracking is a priority.
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On the modulus of elasticity and strain capacity of Self-Compacting Concrete incorporating Rubber Aggregates
Resources Conservation and Recycling, 2008Co-Authors: Anaclet Turatsinze, M. GarrosAbstract:Abstract Cement-based materials suffer from low tensile strength and poor strain capacity. They are brittle and highly sensitive to cracking, notably to shrinkage cracking, which is particularly detrimental for large surface areas. This paper focuses on the properties of a Self-Compacting Concrete (SCC) incorporating Rubber Aggregates, obtained by grinding end-of-life tyres, as a partial replacement for natural Aggregates. Results show that the new cementitious material goes against some governing principles of mechanical behaviour of ordinary cement-based concrete. In particular, the modulus of elasticity of Rubberized SCC is reduced and its variation with Rubber Aggregate content does not obey the conventional empirical relationship of modulus of elasticity with compressive strength. The strain capacity of SCC was quantified through flexural bending tests, which demonstrated that strain capacity increased when Rubber Aggregates were incorporated in concrete. This response is interpreted as a result of the ability of Rubber Aggregates to reduce the stress singularity at the first crack tips running into the Rubber/cement–matrix interface, a mechanism slowing the cracking kinetics and delaying macrocrack localization. In such conditions, Rubberized SCC is expected to be suitable when resistance to the cracking due to imposed deformation is a priority. This type of composite with low modulus of elasticity is also suitable for Controlled Modulus Columns (CMC) foundations, the ultimate solution for improving very soft soils subjected to settlement or stability problems caused by insufficient bearing capacity. Incidentally, the use of Rubber Aggregates in SCC provides an opportunity to recycle non-reusable end-of-life tyres.
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Potential of Rubber Aggregates to modify properties of cement based-mortars: Improvement in cracking shrinkage resistance
Construction and Building Materials, 2007Co-Authors: Anaclet Turatsinze, S. Bonnet, J. L. GranjuAbstract:Abstract Cement-based materials suffer from their low tensile strength and poor strain capacity: they are sensitive to cracking, above all to shrinkage cracking. Enhancing the cracking resistance of cementitious materials is the objective of a broad ongoing research programme. In this regard, the aim of this work is the design of a cementitious composite exhibiting high strain capacity before localised cracking. It was assumed that the use of Aggregates with low elastic modulus could be a solution. Rubber Aggregates obtained from shredded non-reusable tyres were used, conferring an additional environmental interest on the study. As expected, results show that Rubberised mortars exhibit a lower modulus of elasticity and have higher tensile capacity for deformation before macrocrack formation. However, there is one drawback: a decrease in the modulus of elasticity of a cement-based material is accompanied by a decrease in its strength. Results also confirm that Rubber Aggregate incorporation increases length change due to shrinkage. In contrast, ring-test results demonstrate that the strain capacity enhancement provided by Rubber Aggregate incorporation largely offsets the additional shrinkage length changes: shrinkage cracking is delayed and, when it occurs, the crack network exhibits thin crack openings which are less detrimental.
Farhad Aslani - One of the best experts on this subject based on the ideXlab platform.
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The effect of specimen geometry on the compressive and tensile strengths of self-compacting Rubberised concrete containing waste Rubber granules
Structures, 2020Co-Authors: Afsaneh Valizadeh, Fatemeh Hamidi, Farhad Aslani, Faiz Uddin Ahmed ShaikhAbstract:Abstract Self-compacting Rubberised concrete (SCRC) has been received great attention in recent years as an environmental remediation to not only fabricate sustainable and durable civil engineering structures, but also to take the very first steps towards resolving the issue of waste tyres abandoned in the nature. As a step forward in evaluating the structural performance of SCRC, the current research investigates the impacts of specimen size and specimen shape on the compressive and tensile strengths of SCRC containing 0%, 10%, and 20% crumb Rubber Aggregates (i.e., CSCC, SCRC10 and SCRC20) by means of both experimental and fracture mechanics-based theoretical approaches. Cubic specimens with dimension of 100 m m and 150 m m for assessing the compressive strength, cylindrical specimens with dimension of Φ 100 × 200 m m and Φ 150 × 300 m m for the both compressive and splitting tensile strengths measurement, and prism specimen with dimension of 100 × 100 × 400 m m for the flexural strength measurement were casted. The analytical study was performed based on the modified size effect low (MSEL) and adjusting its parameters by applying the experimental results, to establish the correlation between the mechanical properties of SCRC with the geometry of the structural element. Moreover, the relationship between the modulus of rupture and compressive strength of the SCRC has been also pioneered, based on the design codes recommended for the self-compacting concrete. The results show difference between the compressive strength of the cube-shaped specimen with standard cylinder specimen is more significant for mixes with 20% Rubber Aggregates rather than that for the SCRC with less than 20% Rubber Aggregate. Increasing the Rubber Aggregates content led to the significant size effect on the tensile strength of SCRC. The MSEL model predictions are in acceptable agreement for cubic specimen with the experimental data obtained for the CSCC and SCRC10 and for cylindrical specimen, the impact of varying the specimen size on the compressive strength weakened by increasing the Rubber Aggregate content.
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Experimental investigation into Rubber granules and their effects on the fresh and hardened properties of self-compacting concrete
Journal of Cleaner Production, 2018Co-Authors: Farhad Aslani, Dominic Law Yim WanAbstract:Abstract Self-compacting concrete (SCC) is a highly flowable form of concrete which can be applied in complex formworks consisting of congested reinforcement without the use of any or little mechanical vibration. Over the past decades, the excessive accumulation of waste Rubber tyres in Australia has led to significant research in the development of waste Rubber materials to be incorporated in the concrete industry. The replacement of natural Aggregates in SCC with those of Rubber Aggregates from waste tyre develops into what is referred to as self-compacting Rubberised concrete (SCRC). This form of concrete provides a sustainable alternative which assists in minimising the environmental damages associated with the disposal of waste tyres. This project aims to develop information about the fresh and hardened properties of SCRC at incremental Aggregate replacements using three different Rubber Aggregate sizes. The fresh properties were investigated in accordance with the guidelines provided by the European Federation National Representing of Concrete using the slump flow, T 500 , and J-ring tests. Hardened properties include 7 and 28 day compressive and tensile strengths, hardened density testing, and compressive stress-strain behaviour at 28 days. In this study optimum crumb Rubber Aggregates replacement percentage in SCC and optimum crumb Rubber Aggregates size in SCC have been presented and also optimal mix design of SCRC will be assessed to optimise fresh and hardened properties.
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Assessment and development of high-performance fibre-reinforced lightweight self-compacting concrete including recycled crumb Rubber Aggregates exposed to elevated temperatures
Journal of Cleaner Production, 2018Co-Authors: Farhad Aslani, Jack KelinAbstract:Abstract Recycled crumb Rubber is a material created by grinding and commutating used tyres. There is no doubt that the increasing piles of tyres create environmental concerns. The long term goal of this paper is to find a means to dispose of the crumb Rubber in lightweight self-compacting concrete (SCC) and still provide a final product with good engineering properties. This paper has considered replacement of natural normal-weight Aggregates with crumb Rubber Aggregates and lightweight scoria Aggregate together with the addition of macro fibres which provides a sustainable alternative which assists in minimizing the environmental damages associated with the disposal of waste tyres. Also, the purpose of this study is to determine the effect of fibres on fresh and mechanical properties in additional to the performance of the concrete after exposure to elevated temperatures. Investigation has been performed after concrete exposure to both room and elevated temperatures. Fibre reinforcement were added to a control mix containing 80% replacement of traditional coarse Aggregate with lightweight scoria Aggregate and 20% replacement of traditional fine Aggregate with crumb Rubber Aggregate. Steel and polypropylene (PP) fibres were explored so as to ascertain the benefits each fibre can provide through a range of temperatures. Nine mixes were prepared; a control mix and four mixes per each fibre with increasing fibre addition. Chemical admixture dosages were adjusted so as to achieve the desired slump flow. Experimental program investigated the fresh properties of the SCC through slump flow, slump flow T500 and J-ring tests. Mechanical properties were investigated after 28 days curing, standard 100 × 200 mm cylinder specimens were subjected to compressive and indirect tensile tests after exposure to 25, 100, 300, 600 and 900 °C. Compiled results will be compared to those of the control mix.
Jose Aguiar - One of the best experts on this subject based on the ideXlab platform.
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physical and mechanical performance of concrete made with waste Rubber Aggregate glass powder and silica sand powder
Journal of building engineering, 2019Co-Authors: Samiha Ramdani, Abdelhamid Guettala, M L Benmalek, Jose AguiarAbstract:Abstract This study presents experimental results about the effect of incorporating waste Rubber Aggregates in combination with waste glass powder or silica sand powder obtained from dune natural sand, on the performances of cementitious mixtures. Rubber Aggregates (RW) were used to replace crushed sand in concrete mixes with ratios of 10%, 20%, 40% and 60%, while glass powder (GP) and natural sand powder (SP) were used to replace 15% of the cement weight. Nine different forms of concrete with the separate wastes and with the combination of them were designed and prepared. The mixtures were characterized in the fresh and hardened states by means of workability, fresh density, compressive and tensile strengths , propagation of ultrasonic waves and deformability tests. The water/binder ratio and superplasticizer percentage of all mixtures were maintained constant. The results showed that the strength increased with the incorporation of glass powder and Rubber Aggregates, especially with 10% and 20% RW contents. In addition, the developed Rubberized concrete with the incorporation of glass powder presented higher fresh density and deformability, compared to the cementitious Rubberized mixtures without GP. Furthermore, the simultaneous incorporation of Rubber waste and glass powder enhanced the concretes workability due to the low GP and RW water absorptions.
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Fresh State Properties of Concrete Incorporating Scrap Tire Rubber
Periodica Polytechnica Civil Engineering, 2016Co-Authors: Malika Medine, Habib Trouzine, Jose AguiarAbstract:The purpose of this work is to study fresh lightweight concrete containing recycled tire Rubber Aggregates. An experiment on concrete obtained by incorporating Rubber Aggregate with a ratio replacement of 5, 7.5 and 10% is done to evaluate the effect of these Aggregates on the workability of two sets of concrete specimens. In the first set, coarse Aggregates were replaced by different percentages by weight of granulate Rubber and in the second set both coarse Aggregates and sand were replaced Rubber granulate and crumb Rubber. Density, air content, compaction and slump tests are performed on the seven mixtures. Taking into account the density and water absorption differences between the natural Aggregates and the Rubber Aggregates, the validity of the tests results are discussed. The results show that incorporating these Rubber Aggregates affects most rheological properties of lightweight concrete, for some application of concrete incorporating waste tire, Rubber particles should be treated.
Faiz Uddin Ahmed Shaikh - One of the best experts on this subject based on the ideXlab platform.
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The effect of specimen geometry on the compressive and tensile strengths of self-compacting Rubberised concrete containing waste Rubber granules
Structures, 2020Co-Authors: Afsaneh Valizadeh, Fatemeh Hamidi, Farhad Aslani, Faiz Uddin Ahmed ShaikhAbstract:Abstract Self-compacting Rubberised concrete (SCRC) has been received great attention in recent years as an environmental remediation to not only fabricate sustainable and durable civil engineering structures, but also to take the very first steps towards resolving the issue of waste tyres abandoned in the nature. As a step forward in evaluating the structural performance of SCRC, the current research investigates the impacts of specimen size and specimen shape on the compressive and tensile strengths of SCRC containing 0%, 10%, and 20% crumb Rubber Aggregates (i.e., CSCC, SCRC10 and SCRC20) by means of both experimental and fracture mechanics-based theoretical approaches. Cubic specimens with dimension of 100 m m and 150 m m for assessing the compressive strength, cylindrical specimens with dimension of Φ 100 × 200 m m and Φ 150 × 300 m m for the both compressive and splitting tensile strengths measurement, and prism specimen with dimension of 100 × 100 × 400 m m for the flexural strength measurement were casted. The analytical study was performed based on the modified size effect low (MSEL) and adjusting its parameters by applying the experimental results, to establish the correlation between the mechanical properties of SCRC with the geometry of the structural element. Moreover, the relationship between the modulus of rupture and compressive strength of the SCRC has been also pioneered, based on the design codes recommended for the self-compacting concrete. The results show difference between the compressive strength of the cube-shaped specimen with standard cylinder specimen is more significant for mixes with 20% Rubber Aggregates rather than that for the SCRC with less than 20% Rubber Aggregate. Increasing the Rubber Aggregates content led to the significant size effect on the tensile strength of SCRC. The MSEL model predictions are in acceptable agreement for cubic specimen with the experimental data obtained for the CSCC and SCRC10 and for cylindrical specimen, the impact of varying the specimen size on the compressive strength weakened by increasing the Rubber Aggregate content.
Matthew R. Hall - One of the best experts on this subject based on the ideXlab platform.
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crumb Rubber Aggregate coatings pre treatments and their effects on interfacial bonding air entrapment and fracture toughness in self compacting Rubberised concrete scrc
Materials and Structures, 2013Co-Authors: Khalid B. Najim, Matthew R. HallAbstract:The interfacial-bonding, interfacial transition zone (ITZ), and porosity are regarded as the key factors affecting hardened concrete properties. The aim of this study was to experimentally improve the bonding between the Rubber Aggregate and cement paste by different methodologies including water washing, Na(OH) pre-treatment, and both cement paste and mortar pre-coating. All methods were assessed by determining mechanical and dynamic properties, then correlating this with ITZ porosity and interfacial gap void geometry, along with quantification of the fracture energy during micro crack propagation using fractal analysis. The results indicated that pre-coating the Rubber by mortar gave the best results in terms of fracture toughness and energy absorption showing good agreement between observations made at both micro and macro scales.
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Workability and mechanical properties of crumb-Rubber concrete
Proceedings of the Institution of Civil Engineers - Construction Materials, 2013Co-Authors: Khalid B. Najim, Matthew R. HallAbstract:The addition of crumb-Rubber Aggregate has a significant effect on concrete mix apparent porosity which affects both the plastic state workability and hardened state mechanical properties. New experimental data are presented and analysed to better understand this behaviour. Crumb-Rubber-modified concrete exhibits reduced slump while maintaining a high compaction factor in the plastic state. Structural Rubber-modified concrete (fcu > 17 MPa, ρd = > 2000 kg/m3) can be designed with crumb-Rubber substitution up to 20%wt fine Aggregate replacement or up to approximately 15%wt coarse Aggregate or coarse + fine Aggregate replacement. The dynamic modulus of elasticity can be predicted reliably using the empirical equation Ed = 0·524fcu + 15·5 which allows the ultrasonic pulse velocity test to be used as an indicative assessment of mix quality. ‘Good’ quality Rubber-modified mixes can be produced using 10%wt fine Aggregate and coarse + fine Aggregate replacement mixes, and up to 20%wt coarse + fine Aggregate ...
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Mechanical and dynamic properties of self-compacting crumb Rubber modified concrete
Construction and Building Materials, 2012Co-Authors: Khalid B. Najim, Matthew R. HallAbstract:Abstract In this study, the mechanical and dynamic properties of Self-Compacting Rubberised Concrete (SCRC) were experimentally investigated. Crumb Rubber from scrap tyres was used as a partial replacement for Fine Aggregate (FA), Coarse Aggregate (CA) and combined Fine and Coarse Aggregate (FCA) at 5, 10, and 15 wt% proportions. Incorporating Rubber Aggregates generally has a detrimental effect on the mechanical strength, but gives improved strain capacity resulting in significant reductions in the flexural Crack Mouth Open Displacement (CMOD), compared to the reference mix. Structural grade SCRC (fc > 17 MPa; ρ > 2000 kg/m3) can be obtained with up to ∼260 kg/m3 (equivalent to 15 wt%) in all forms of crumb Rubber Aggregate substitution. The Dynamic Modulus and Ultrasonic Pulse Velocity decreased as the proportion of Rubber substitution was increased, however SCRC has superior vibration damping behaviour in all cases with up to 230% enhancement in damping ratio and damping coefficient for the CR 15 wt% mix.
