THE EFFECTS OF PARTIAL REPLACEMENT OF SHARP SAND WITH LATERITE IN BLOCK PRODUCTION

Abstract

This research works seek to find out the effects of partial replacement of sharp sand with laterite in blockproduction in Awka Anambra State, Nigeria. Lateralized Sandcrete blocks were made with lateritic soilreplacing the conventional fine aggregate (local river sand) in steps of 2.5% up 12.5%. %. Theircompressive strengths were determined to check for conformity with standard sandcrete block as specifiedin the Nigerian National Building Code (2006) with a view to determine the acceptable percentagereplacements. Solid sandcrete blocks were produced with fine aggregate (sharp sand and laterite) andcement in the ratio 1:6 by mass. Two and halve percent (2.5%) of the conventional fine aggregate (sharpsand) was replaced with the lateritic soil and then 5%, 7.5%, 10%, and 12.5%. Four (4) blocks at eachpercentage replacement of the conventional fine aggregate with the lateritic soil content were produced,cured weighed and tested for the 7th day, 14th day, 21th day and 28th day compressive strength and theaverage values of the values are taken as actual parameters. For control, four blocks were molded withoutreplacement, that is, with 100% conventional sand. They were prepared to have water/cement ratio thatwill ease molding as this is to simulate site conditions. They were cured by sprinkling with water for 28days and crushing test was performed on the samples to determine their compressive strengths. Thecompressive average strength of the control (0%), 2.5%, %, 7.5%, 10%, and 12.5% percentagereplacements are recorded to be 10.6 N/mm2 , 8.8 N/mm2 , 8.5 N/mm2 , 7.5 N/mm2 , 6.9 N/mm2 , and 5.7N/mm2 respectively. The values and graph showed that there is an approximate linear decrease incompressive strength with increasing sand replacement with laterite. The minimum compressive strengthof blocks for walling units is 1.7 N/mm2 as specified in the Nigerian National Building Code (2006).Hence compressive strength results have gotten show conformity with standard comprehensive strengthfor sandcrete block as specified in the Nigerian National Building Code (2006). The lowest compressivestrength recorded is 5.7 N/mm2 at 12.5% percentage replacement which is 4 N/mm2 (235.2%) greater thanthe allowable minimum compressive strength, therefore Laterite sandcrete blocks of the mix ratio of 1:6and percentage replacements 2.5%, 5%, 7.5%, 10% and 12.5% are good for walling unit. These percentagereplacements can be recommended to the block making industries within Awka and its environment witha view to encouraging utilization, though it is encouraged to confirm the percentage before embarking onmass block production.6