Abstract
One of the important problems in fine aggregate is the contaminated with interior sulfates in
manufacturing concrete in Iraq. Within standard specifications a difficult to obtain of well-graded
fine aggregate with sulfates content is existed. The present research is devoted to enhancement of
some properties of self-compacting concrete with fine aggregate contains internal sulfates by
partial replacement of gypsum to fine aggregate by weight. This study is bifurcate of selfcompacting
concrete they are: first category is incorporating powder of limestone (LSP) in selfcompacting
concrete and the second one is incorporating 10% rise husk ash (RHA) plus powder of
limestone (LSP). The investigated scales of fine aggregate with sulfates contents were ( 0.37%,
0.5%, 1.0%, and 1.5%) which is corresponding replacement by weight of cement equal of (3.74%,
3.99%, 4.96% and 5.93%) for mixes contained limestone powder and of (3.76%, 4.01%,4.98% and
5.96%) for mixes contains rise husk ash plus powder of limestone. Experimental program of this
study is bifurcate; first one is using superplasticizers and fillers to produce self-compacting
concrete then determine the workability. Second one is to evaluate the mechanical properties such
as splitting tensile strength and compressive strength. It was noticed that, the exemplary content of
gypsum was by weight of cement for all mixes was 0.5%. While increase in compressive strength
in a range between 5.9% and 10.1%, and in tensile strength in a range between 1.2% and 8.5% for
mixes of self-compacting concrete with limestone powder plus rise husk ash instead of limestone
powder.
