Application of recycled concrete aggregates as alternative granular infills in hollow segmental block systems

Geosynthetic Reinforced Segmental Retaining Walls (GR-SRWs) are developing as well recognized earth retaining structures for their manifold economic and technical advantages. It is a matter of great concern that still now a huge volume of natural coarse aggregate is used as filler in GR-SRWs, thus depleting natural resources and presenting a challenge for sustainable development. The main objective of this study is to examine the effect of recycled coarse aggregates (RCAs) used as alternative granular infills in hollow facing column. As granular infills, two types of recycled aggregates were used along with natural coarse aggregates (NCAs). Recycled aggregates were primarily selected based on the grading of the source waste concretes to investigate its effect on the frictional behavior of recycled aggregates used as infillers. Purely frictional capacity of I-Block infilled with recycled aggregates was compared to those infilled by fresh aggregates. To eliminate the effect of shear pins on interface shear capacity of I-Block system infilled with gravels, none were used in purely frictional shear. A series of direct shear tests was performed using a specially designed and fabricated direct shear apparatus to assess the frictional behavior of infilled blocks under different normal loading conditions. The tests were conducted following the exiting ASTM and National Concrete Masonry Association (NCMA) test protocols. The test results were outlined in the form of shear stress–displacement relationship to compare the effect of recycled aggregate against the fresh aggregate. Shear capacity envelopes were also plotted using Mohr–Coulomb failure criterion to find out the angle of friction for each case. Test results reveal that the angle of friction of the blocks infilled with the recycled aggregate is almost equal to those with the fresh aggregate. The results also show that compressive strength of the source waste concretes has a little or no effect on the frictional performance of recycled concrete aggregates used in facing units.