A comparative investigation of the unit cost for the preparation of modified sand and clay bricks from rice husk waste

Abstract

Rice husk (RH) is produced in large quantities in Egypt and burned in open atmosphere to produce RH ash (RHA), which poses a great risk to the environment by affecting the land and the surrounding areas in which it is disposed of. Consequently, this work is an attempt to prepare a modified sand/lime brick, employing a mixture of sand and different percentages of RHA (5%, 10%, and 15%) with 15% of burned calcite. The compressive strength and bulk density of the prepared sand bricks were determined. Further, the phase composition and structure of the surface of the samples were also identified by Fourier-transform infrared (FT–IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) techniques. It was confirmed that the modified sand/lime brick, composed of 80% sand, 5% RHA, and 15% lime, exhibited the best results. The obtained bulk density and compressive strength were 1.82 g/cm3 and 103 kg/cm2, respectively. A comparative estimation of the unit cost of the modified RHA–sand/lime brick and those of two other brick types, namely clay/RH and cement/RHA bricks, which had been prepared and reported by the authors, was performed. It was concluded that the partial replacement of RH, as solid agricultural waste, in the manufacture of building bricks can reduce the cost significantly, as 20% RH substitution (yielding 5% RHA) in the sand brick, 10% RH substitution in the clay brick, and also 20% RH substitution (yielding 5% RHA) in the cement brick, resulting in 14%, 42.8%, and 25% unit cost reductions, respectively.