Abstract
In this paper, the effect of the original aggregate size of the recycled aggregate on the mechanical properties of the recycled aggregate concrete was evaluated. A series of concretes were produced in which natural aggregates, recycled aggregates, and original aggregates in recycled aggregates were matched for a single particle size distribution curve. The replacement levels of recycled aggregate were 25% and 50%, and equivalent mortar volume mix design was applied for recycled aggregate concrete. The results show that the mechanical strength of recycled aggregate concrete increases with increasing original aggregate size. This effect was observed to be greater in concrete using recycled aggregate with a high residual mortar content.
Highlights
Coarse aggregate occupies the largest volume of raw materials in concrete [1], and is one of the major parameters that can significantly affect the performance of concrete [2].various characteristics such as shape [3], size [4], surface condition [5,6], and type [7] of coarse aggregate have been investigated worldwide
This is associated with an increase in the interfacial transition zone (ITZ), which is considered the weakest phase of concrete where microcracks are most likely to exist as the aggregate size increases [14]
The results showed that recycled aggregate concrete (RAC) with a maximum aggregate size of 19 mm had the highest strength, and RAC made with a maximum size of 31.5 mm had the lowest strength
Summary
Coarse aggregate occupies the largest volume of raw materials in concrete [1], and is one of the major parameters that can significantly affect the performance of concrete [2]. The authors of that study concluded that a smaller maximum size of RCA resulted in a greater reduction in the strength of RAC due to an increase in the amount of old residual mortar present in RCA. According to the above literature review, the effect of the RCA size on the properties of concrete seems ambiguous, more research is needed in depth This may be associated with the fact that the increase in the RCA size includes both favorable (e.g., enhanced RCA quality) and unfavorable factors (e.g., increasing ITZ and heterogeneity in RAC matrix) to the properties of concrete. In this study, in order to evaluate the effect of the OA size in RCA on properties of RAC, the particle size of RCA and OA was determined using the residual mortar removal method, respectively, and the fresh and hardened characteristics were investigated. The significance of the paper lies primarily in the consideration of this parameter in the experimental course, so that the obtained results can be clues to improve the low performance of RAC
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