Influence of rice husk ash, lime and cement on compaction and strength properties of copper slag

A total of 77 tests have been carried out on various mixes of copper slag (CS), rice husk ash (RHA), hydrated lime (L), ordinary Portland cement (C) in order to find their compaction and strength characteristics. Modified Proctor compaction (MPC) and unconfined compressive strength (UCS) tests have been performed to investigate the compaction and strength behavior of the various combinations, respectively. The void ratio and specific gravity of the individual constituent materials and that of the developed mixes have also been investigated. In appendage X-ray fluorescence (XRF) and X-ray diffraction (XRD) tests were carried out on individual constituent materials and optimum UCS tested samples in order to study the chemical composition and strength enhancement compounds, which were formed. The test results indicated a decrease in MDD, specific gravity and UCS as the percentage of RHA, L and C in a mix is increased and that of the copper slag decreased. Further, with the increase in curing period from 0, 7, 14 and 28 days, there was an improvement in UCS value. A multilinear linear regression analysis (MLRA) has been carried out on the results obtained from UCS tests and the corresponding equation has been developed. Out of the various mixes, the mix with composition of 75% copper slag and 20% rice husk ash mixed with 5% cement has been found to be optimum, in context of its strength. The test results revealed a potential of the developed mixes to be used as a construction material for sub-base layers of the flexible pavements, construction of embankments and as filler material.