A critical review of the resulting effective water-to-cement ratio of fine recycled aggregate concrete

Sosa, María Eva; Zaccardi, Yury Villagrán; Zega, Claudio Javier

doi:10.1016/j.conbuildmat.2021.125536

Cited by 45 publications

(43 citation statements)

References 37 publications

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“…However, the consciousness of associated embodied carbon in concrete and its propagation with increased water content will define the trajectory of new phases of low carbon concrete. While complimenting the efforts of various studies [ 76 , 78 , 79 , 80 , 81 ] on the effect of water on normal concrete where the consideration for associated embodied carbon was either minimal or negligible, there is a need to establish the desired pattern for water in embodied carbon and concrete strength to correlate future results. This section presents the variability of water from selected literature on embodied carbon and concrete strength.…”

Section: Methodsmentioning

confidence: 99%

Optimisation of Embodied Carbon and Compressive Strength in Low Carbon Concrete

et al. 2022

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To improve the prediction of compressive strength and embodied carbon of low carbon concrete using a program algorithm developed in MATLAB, 84 datasets of concrete mix raw materials were used. The influence of water, silica fume and ground granular base slag was found to have a significant impact on the extent of low carbon concrete behaviour in terms of compressive strength and embodied carbon. While the concrete compressive strength for normal concrete increases with reducing water content, it is observed that the low carbon concrete using lightweight aggregate material increases in compressive strength with an increase in embodied carbon. From the result of the analysis, a function was developed that was able to predict the associated embodied carbon of a concrete mix for a given water-to-cement ratio. The use of an alkaline solution is observed to increase the compressive strength of low carbon concrete when used in combination with ground granular base slag and silica fume. It is further shown that ground granular base slag contributes significantly to an increase in the compressive strength of Low carbon concrete when compared with pulverised fly ash. The optimised mix design program resulted in a 26% reduction in embodied carbon and an R2 value of 0.9 between the measured compressive strength and the optimised compressive strength.

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Section: Methodsmentioning

confidence: 99%

Optimisation of Embodied Carbon and Compressive Strength in Low Carbon Concrete

et al. 2022

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“…As shown in Equation (2), the W SSD of RA is firstly calculated and then multiplied by a reduction coefficient to obtain the amount of additional water that can be added to the slurry during the RAC preparation or used to pre-soak RA before the preparation. Another reason for adopting the reduction coefficient is that cement particles would form a water-blocking film on the surface of RA so that the latter cannot ever reach the SSD state inside the slurry [ 50 ].

where M a , M aw , and α are the mass of RA, the mass of additional water, and a reduction coefficient, respectively.…”

Section: Absorption Behaviors and Moisture States Of Ramentioning

confidence: 99%

“…

where M a , M aw , and α are the mass of RA, the mass of additional water, and a reduction coefficient, respectively. The value of α has been discussed in detail in a recent review [ 50 ]. In general, when the w/b ratio of RAC ranges from 0.35 to 0.50, α should be taken as 72–80% [ 51 ].…”

Section: Absorption Behaviors and Moisture States Of Ramentioning

confidence: 99%

Measurement of Water Absorption of Recycled Aggregate

Duan

Zhao

et al. 2022

Materials

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Owing to the high absorption capacity of recycled aggregate (RA), it is crucial to accurately measure its saturated-surface-dried water absorption (WSSD), which largely affects an effective water-to-binder ratio of recycled aggregate concrete. In this study, existing measurement methods for the WSSD of RA are extensively reviewed, including Wiping, Slumping, Centrifugation, Infrared, Evaporation, Airflow drying, Conductivity, Pycnometer, Hydrostatic balance, and Extrapolation. In particular, the physical principles and operability of these methods are emphasized. It was determined that the accuracy of all test results was not satisfactory. For example, the water in pores with an open-ended direction that was opposite to the centrifugal force could largely be retained. In Airflow drying, the temperature change was significantly delayed. In addition, in Hydrostatic balance, RA would pre-absorb water before determining the initial reading. Therefore, several suggestions for optimizing these methods are presented, such as the combination of Evaporation and Airflow drying, the liquid selection in Hydrostatic balance, and the addition of a tiny mixer in each centrifuge tube. In summary, this review facilitates the development of an accurate and convenient method for measuring the WSSD of RA.

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“…While higher values of the water/cement ratio results in a more workable concrete, the risk of segregation is also high. On the other hand, a too low value of the water/cement ratio, without the use of proper water reducing admixtures, may result in an improper binding of all aggregates within the cement paste [1,2]. Either way, the end result is a material that cannot fulfill its role for structural applications.…”

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confidence: 99%

“…The feasibility of using recycled aggregates from demolition wastes, in the context of the circular economy paradigm, resulted in many research works being published in the scientific literature. Their effect on the mechanical properties of mortar or concrete is hard to fully understand and quantify, given the large variety in the characteristics of the recycled aggregates depending mostly on their origin and initial composition [2,17,18]. The general consensus is that the mechanical and durability properties of mortar and concrete incorporating construction demolition wastes decrease, and new methodologies are investigated to improve the quality of recycled aggregates from these sources.…”

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confidence: 99%