An investigation on effect of aggregate distribution on physical and mechanical properties of recycled aggregate concrete (RAC)

Abstract

The aim of the study is to optimize the aggregate gradation curve (AGC) for recycled aggregate concrete (RAC). Accordingly, TS 802 aggregate gradation curves such as A16, B16 and C16 and, also two proposed AGCs such as G1 and G2 are examined in the experiments. Hence, in total, 10 mixes are designed in consideration of A16, B16, C16, G1 and G2. The physical (density and water absorption) and the mechanical (compressive strength) properties are determined conducting the standard tests at the age of 28th days after a standard 22±2oC water curing. Also, a criterion weighting method such as Entropy Method is used in the evaluation of the properties of concretes and the weights of the properties of concretes are determined. Then, TOPSIS is used to find the best concrete in consideration of the design parameters and test results for the selection of the optimum AGC. As a result, the influence of AGC on the properties of natural aggregate concretes (NACs) and RACs are unsimilar and while A16 results in a denser NAC with higher compressive strength, C16 can be offered to decrease the open pore content of RAC in terms of water absorption leading a durable concrete with a higher compressive strength. Besides, the results of Entropy Method present interesting findings, and the coarse aggregate ratio in the mix is found as the most effective parameters among the investigated design parameters. However, the best AGCs are found as A16 for NAC and G2 for RAC according to TOPSIS results. It is concluded that further investigations are required.

Effects of single-walled carbon nanotubes and steel fiber on recycled ferrochrome filled electrical conductive mortars

“…However, there are still gaps in the literature on increasing the conductivity of cement and aggregate composition, which are matrix elements in concrete. Also, there are many studies on the evaluation of recycled aggregate and slag materials in concrete [26][27][28]. The present study investigates the electrical, mechanical, physical, and microstructural properties of electrical conductive mortars containing 100% recycled ferrochrome sand.…”