Strength prediction model and methods for improving recycled aggregate concrete

Younis, Khaleel H.; Pilakoutas, Kypros

doi:10.1016/j.conbuildmat.2013.09.003

Cited by 171 publications

(85 citation statements)

References 33 publications

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“…Weak interfacial transition zone (ITZ) between the recycled concrete aggregate (RCA) and the cement matrix has also been identi ed [1,9,10]. Moreover, the presence of more than one ITZ in the RAC is another reason for the low quality of the RAC [1,9,11]. In RAC, there are three ITZs : ITZ1 which is between the old attached mortar and the natural aggregate, ITZ2 which is between the natural aggregate and the new cement mortar, and ITZ3 is between the old and new cement mortars [1] (Figure 1).…”

Section: Introductionmentioning

confidence: 99%

“…For example, vast quantities of building rubbles have been generated in Iraq over the last decades as a result of conflicts and terrorist attacks. At the global level, more than 500 million tons of construction and demolition waste (CDW) and building rubbles are generated worldwide annually [1]. Such a huge quantity of CDW requires substantial areas of land to dispose of, causing serious environmental issues.…”

Section: Introductionmentioning

confidence: 99%

“…Nonetheless, the properties of the recycled aggregate concrete (RAC), as reported by the researchers, are inferior to that of the natural aggregate concrete (NAC). RAC exhibits low compressive, tensile, and flexural strength as well as high water absorption, porosity, and shrinkage [1,[3][4][5]. For these reasons, most codes of practice allow the natural aggregate in concrete to be only partially (20-30%) replaced by RA, especially in structural applications [6].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…One way is recycling the CDW and reusing them as aggregate and as an alternative to the natural aggregate in concrete. e utilization of recycled aggregate (RA) derived from processing CDW in concrete can save the environment through conserving the scarce landfill areas and reduce the consumption rate of the natural resources of aggregates [1,2]. e use of the RA generated from processing CDW of concrete elements in new concrete has been investigated for decades.…”

Section: Introductionmentioning

confidence: 99%

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Feasibility of Using Nanoparticles of SiO₂ to Improve the Performance of Recycled Aggregate Concrete

Younis

Mustafa

2018

Advances in Materials Science and Engineering

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e aim of this paper was to examine the feasibility of using nanoparticles of SiO 2 (nanosilica) to improve the performance of recycled aggregate concrete (RAC) containing recycled aggregate (RA) derived from processing construction and demolition waste of concrete buildings. e examined properties include compressive strength, splitting tensile strength, and water absorption. e study also includes examining the microstructure of RA and RAC with and without nanoparticles of SiO 2 . In total, nine mixes were investigated. Two mixes with RA contents of 50% and 100% were investigated and for each RA content; three mixes were prepared with three different nanoparticles dosages 0.4%, 0.8%, and 1.2% (by mass of cement). A control mix with natural aggregate (NA) was also prepared for comparison reasons. e results show that nanoparticles of silica can improve the compressive strength, tensile strength, reduce the water absorption, and modify the microstructure of RAC.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Feasibility of Using Nanoparticles of SiO₂ to Improve the Performance of Recycled Aggregate Concrete

Younis

Mustafa

2018

Advances in Materials Science and Engineering

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Optimisation and prediction of compressive properties for concrete containing recycled aggregates and rice husk ash using response surface methodology (RSM)

Ma,

Wang,

Huang

et al. 2023

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Rice husk ash (RHA), an agricultural by‐product, has been added as supplementary cementitious material (SCM) in concrete mixture to improve the compressive properties of recycled aggregate concrete (RAC) in recent years. This study aimed to optimise the mixture design of RAC considering two variables: the replacement ratio (wt.%) of recycled aggregate (RA) to natural aggregate (NA) with three levels (0%, 50% and 100%) and the replacement ratio (wt.%) of RHA to cement with three levels (0%, 10% and 20%). Compression test was implemented at concrete age of 28 days based on the full factorial experiment. By means of response surface methodology (RSM), the optimised RA replacement ratio and RHA replacement ratio can be calculated with respect to the compressive strength and E‐modulus at 28 days, and vice versa the compressive strength and E‐modulus at 28 days of RAC containing RHA can also be predicted. According to response surface modelling, the compressive strength reaches the maximum value when the RA replacement ratio is 0% and the RHA replacement ratio is 7%, and the E‐modulus would reach the maximum when the RA replacement ratio is 17% and the RHA replacement ratio is 7%. The determination coefficient (R2) and adjusted coefficient (R2adj) for the compressive strength model are 0.9632 and 0.9544 respectively, and for the E‐modulus model are 0.9319 and 0.9157 respectively, showing that the models developed by RSM are relatively well correlated with the experimental results.

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Postcracking tensile behavior of blended steel fiber‐reinforced concrete

Wang

Figueiredo

et al. 2018

Structural Concrete

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Fiber blends have the potential to improve the mechanical and sustainability credentials of steel fiber‐reinforced concrete (SFRC), but at which ratios these can work is not known a priori. This paper investigates the uniaxial tensile stress–strain ( σ − ε) relationship of blended SFRC using manufactured steel fibers on their own, or blended with sorted steel fibers recycled from end‐of‐life tires (recycled tire steel fiber [RTSF]), at total fiber dosages of 30, 35, and 45 kg/m3. The accuracy of two σ − ε relations proposed by RILEM TC 162‐TDF and Model Code 2010 is assessed using the experimental results from concrete prisms. By using nonlinear finite element (FE) analysis, it is found that the RILEM approach can lead to significant overestimation (up to 72%) of peak flexural load and energy absorption capacity (up to 39%), while the Model Code 2010 can provide a rather accurate prediction of the energy absorption capacity and some overestimation (less than 34%) of the peak flexural load. Inverse FE analysis is used to determine indirectly the uniaxial tensile σ − ε relations of the examined SFRC mixes, and a simplified trilinear relation for SFRC is proposed. It is concluded that the tensile strength of SFRC with RTSF at a low total fiber dosage is only marginally improved by fiber addition, and the postcracking tensile strengths at different strains can be determined directly from residual flexural tensile strengths (f Ri) of prisms.

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Strength prediction model and methods for improving recycled aggregate concrete

Cited by 171 publications

References 33 publications

Feasibility of Using Nanoparticles of SiO₂ to Improve the Performance of Recycled Aggregate Concrete

Feasibility of Using Nanoparticles of SiO₂ to Improve the Performance of Recycled Aggregate Concrete

Optimisation and prediction of compressive properties for concrete containing recycled aggregates and rice husk ash using response surface methodology (RSM)

Postcracking tensile behavior of blended steel fiber‐reinforced concrete

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Strength prediction model and methods for improving recycled aggregate concrete

Cited by 171 publications

References 33 publications

Feasibility of Using Nanoparticles of SiO2 to Improve the Performance of Recycled Aggregate Concrete

Feasibility of Using Nanoparticles of SiO2 to Improve the Performance of Recycled Aggregate Concrete

Optimisation and prediction of compressive properties for concrete containing recycled aggregates and rice husk ash using response surface methodology (RSM)

Postcracking tensile behavior of blended steel fiber‐reinforced concrete

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Feasibility of Using Nanoparticles of SiO₂ to Improve the Performance of Recycled Aggregate Concrete

Feasibility of Using Nanoparticles of SiO₂ to Improve the Performance of Recycled Aggregate Concrete