Absorption Variation with Particle Size of Recycled Fine Aggregates Determined by the Electrical Method

Abstract

The scarcity of fine natural aggregates and the negative environmental impact of their extraction make it necessary to find new sources of aggregates for the construction industry. The use of recycled aggregates (RA) derived from waste concrete crushing is a viable option for reducing non-renewable raw material consumption. The quality of these aggregates is lower than that of natural aggregates. In particular, the water absorption (WA) of the fine fraction of RA is a topic of constant debate due to the limitations of the standardized practices for determining it. Several methods have previously been proposed concerning this. Among these, the electrical conductivity method has the highest potential for effective WA determination. However, the influence of particle size and shape on the measurement remains unknown. In this study, the electrical conductivity method is applied to determine the WA of different particle size ranges in both natural and recycled aggregates. The results show that the paste content is the main variable that influences the WA of RA, whereas the size and shape of particles have no discernible influence on the measurements made using the electrical conductivity method. The present work expands upon previous studies by demonstrating the universality of the method irrespective of the particle size.

Influence of Recycling Processes on Properties of Fine Recycled Concrete Aggregates (FRCA): An Overview

“…Processes that include the rotor crusher or the ball mill led to reduced absorption because these techniques have a polishing effect that separates the adhered paste from the natural aggregates. Comparing the averages, it can be concluded that the jaw crusher + rotor crusher + sieving process generated FRCAs with [10,12,18,21,32,33,35,38,46,50,52,59,62] and CW [11,16,17,19,[23][24][25]36,42,43,45,47,53,57,87].…”

“…Furthermore, the figures presented Fuller's Curve, which represents the grading of aggregate particles resulting in optimum packing, density, and strength of the concrete mixture [92]. [14,35,38,44,46,50,52,59,62]; (b) particle size distributions of FRCAs from CW according to recycling processes [11,16,[23][24][25]28,36,42,43,45].…”

“…Figure 2 shows the water absorption of FRCA grouped according to these criteria. [10,12,18,21,32,33,35,38,46,50,52,59,62] and CW [11,16,17,19,[23][24][25]36,42,43,45,47,53,57,87].…”

“…The effect of this is an increase in FRCA quality due to a dual effect of reduced absorption and increased oven-dry density. [10,12,[32][33][34][35]38,46,47,50,52,59] and CW [11,16,17,19,[23][24][25]36,42,43,45,53,57,87].…”

“…The adhered paste was evaluated based on the type of source material (LAB or CW) and the type of process. The principle of the main techniques used for determining the adhered paste involves the loss of mass in hydrochloric acid [12,25,32,52]. Nevertheless, due to the use of limestone aggregates, one study [10] utilised a soluble silica subprocedure from ASTM C1084 [97].…”