Properties of High Performance Mortar Using Local Additives


High performance mortar can be produced by using ultrafine particles and superplasticizeradmixtures which reduce water – cement ratio (less than 0.3). In this investigation an attemptwas made to examine the possibility of replacing a part of weight of sand (10 and 20%) or apart of weight of cement (11.5, 17 and 23%) by low cost locally feldspar powder (FP) withoutimpairing the high strength characteristic of the mortar. The experimental work includes thepreparation of the feldspar material as one type of pozzolana, and selection of highperformance mortar mix. Finally the properties of the selected mortar (compressive strength,modulus of rupture, density, pulse velocity, static and dynamic moduli of elasticity) at roomtemperature at 3, 7, 14, 28, 60, 90 and 180 days and after exposure to high temperatures in therange from 150 to 900°C at age 60 days were investigated.The results show that the incorporation of 17% of feldspar powder as a partial replacement ofcement and 4% of superplasticizer by weight of cement to 1:1 cement to sand mortar mixenabled the production of high performance mortar with compressive strength of about 80N/mm2 at 28 days. This mix shows significant drop in compressive strength and modulus ofrupture of about 45 and 60% respectively, while the reduction in static and dynamic moduliwas about 66 and 86% respectively after exposure to 600°C.