INVESTIGATION INTO THE POSSIBLE USE OF POWDERED BURNT BRICK (PBB) AND ORDINARY PORTLAND CEMENT (OPC) ADMIXTURE FOR SANDCRETE BLOCKS PRODUCTION

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Author

Presented To

Department of Environmental Design

ABSTRACT
The thesis is essentially a comparative investigation between using Ordinary Portland Cement (OPC) and an admixture (blended cement of Portland cement (OPC) and Powdered Burnt Brick (PBB). It was directed at ascertaining the suitability or otherwise of the blended cement for use in the production of sandcrete blocks as OPC is used. Three sets of trial mixes of varied composition were produced to determine parameters like optimum water/cement ratio, optimum percentage replacement by weight of the OPC by the PBB It was also used to determine the effect of varying the aggregates/cement ratio. A number of other tests carried out to ascertain properties of specimens produced are as follows. Compressive strength determined for various ages ranging between 3 days and 90 days were found to be generally high. For instance the 28th day strength of specimens for a mix of 1:6 gave a strength of not less than 87% of the 0% replacement when the OPC was replaced by 20% PBB. Split tensile strength, obtained varied between 8 - 11% of the compressive strength of the same mix ratio at 28 days Mixes with the PEJB have higher tensile values than those without. The setting time test revealed that mixes with 0% replacement have bigger initial setting times than those with 10% and 20% replacement But the former have smaller - final setting time than the latter. Since the optimum percentage replacement of the OPC by the PBB is only 20, the cost saving might be small but other advantages like low heat of hydration, high tensile strengths, pride of an additional local material that can be used abound. It was observed that mortar mixes with 20% replacement of OPC by PBB mixes developed strengths that compared favourably with the mortar mixes with 0%replacement. The application of the former in mortars was also recommended in line with the present use of the later.