Effect of Increasing sulphate content in sand on concrete compressive strength

Abstract

The research is studied the increasing of sulphate problem in fine aggregate of concrete and trying to create the solution for some of high sulphate content out of Iraqi standard specification No. 45 – 1984 through study behavior the two concrete mixes 1:1.5:3 & 1:2:4 by vol. with different proportion additions( 0.5,1,1.5,2)% for sulphate in sand for two mixes to know the negative effect for these additions. The two mixes were produced Concrete with lower ( -15.4,-21.7 )% compression consequently by increasing 2% sulphate in 28 days age in comparison with same referential mixes without sulphate . Adding different proportion additions ( 3 – 26 )% cement and( 1,1.5,2,3)% plasticizer from weight of cement to both of mixes to cure this reduction in compressive strength and to know the effect of each them on compression of high sulphate content concrete . The results shows that the large positive effect was happening in compressive strength with high sulphate content up to 2% which is approach to compression of referential mixture 1:1.5:3 and that effect is less in mix 1:2:4 . The different proportion additions of ( 1,1.5,2,3)% plasticizer from weight of cement to both of mixes gave slightly positive effect on reduction of compressive strength particularly in mix1:2:4 for the compressive strength percent is (-12.3,-17.3) % less than referential mixes in comparison with 1:1.5:3 & 1:2:4 consequently with 2% sulphate and 3% plasticizer content .