Effect of compression casting technique on the water absorption properties of concrete made using 100% recycled aggregates

Abstract

Effect of compression casting technique on the water absorption characteristics of low grade 100% Recycled Aggregate Concrete (RAC) of target strength range 11 to 15 MPa to be used in the manufacturing of masonry units is investigated. Water absorption characteristics were determined by performing sorptivity test. Recycled aggregates were produced by crushing laboratory-tested concrete samples of strength ranging from 21 MPa to 28 MPa. Two different ratios of recycled coarse aggregate and recycled fine aggregates were investigated using two different cement contents. For comparison, natural aggregate concrete mixes were also tested. The study parameter included effect of aggregates type, casting pressure, casting technique and cement content on the water absorption properties of RAC. Further, depth of penetration of salt was observed using silver nitrate solution after 3-month immersion in 10% NaCl solution. The results of sorptivity test showed positive impact of compression casting technique on water absorption properties of low grade 100% RAC. Further, results showed that RAC mixes exhibited inferior water absorption properties compared to natural aggregates concrete mixes. Various equations were proposed to predict water absorption of 100% RAC under different conditions of casting pressure and cement content based on initial and secondary rate of water absorption.

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].…”

“…The set of recycling technologies used in combination forms a recycling process. Studies show a wide variety of combinations and number of repetitions of the techniques, but in general, most include at least one crushing process and one screening process, with several studies also incorporating specific treatment technologies [39,59,82].…”

“…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].…”

Laboratory evaluation of a complex treatment technology for reducing water absorption of the pavement subbase aggregate from the blast-furnace slag

“…The issues of reducing water absorption of the construction and building materials are considered in a large number of papers [30][31][32][33][34][35][36][37][38][39][40]. To reduce water absorption of materials, various researchers suggest methods such as the use of nano-TiO2-modified recycled coarse aggregate [30], using the air entraining agent (for mortars) [31], slurry coating modified methods (for recycled coarse aggregate) [32], silane emulsion impregnation [33], cement-silica fume slurry coating method [34], compression casting method (to reduce water absorption properties of concrete) [35], impregnation with spent technical fluids [36], selective crushing [1], enrichment in heavy media [37], jigging [38], porosity enrichment on the friction classifier [39], etc. There is also a known method for reducing water absorption of liquid BFS , including pouring it with a thin layer for faster solidification [40].…”