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This paper is an experimental study that was made on the effects of using Wheat Straw Ash (WSA) as a partial replacement of cement in the concrete mixture. The control specimens with ordinary portland cement (OPC) were made and in other specimens, cement was replaced with 10%, 15%, and 20% of WSA by weight of the cement. Wheat straw locally available was burned to ash in a controlled manner in the oven, which was used in this study. The destructive tests included the compressive strength, modulus of rupture, and splitting tensile strength were carried out on the concrete mixture using WSA at a different percentage of cement replacement and were and compared with control specimens. The tests result gained show that the compressive strength decreases when surrogating cement with WSA. While the modulus of rupture increase with 10 % WSA also, the splitting tensile strength increase with 15 % WSA.

The increase in the demand for cement to produce large quantities for the purpose of reconstruction produce a large amount of cement kilns dust accordingly. The cement kilns has a cementations property and it's using to treats soil. In this study, sand gravel soil (roads subbase) materials has been used to study the effect of the cement kiln dust (CKD) as a partial replacement with the natural dust of subbase till 20% by weight. Three tests procedures have been adopted which are density-moisture relationship, California bearing ratio (CBR), and unconfined compression strength (UCS). The results show significant increasing in density and optimum moisture content, CBR, and UCS with the increasing of CKD content. Bonds induced by the pozzolanic reaction and the absorption of the free water on particles surfaces approaching each other could the cause of increasing density, forming tighten structure, and raising the CBR% values, this reaction needs more water with increasing of CKD that could be caused increasing in the optimum moisture content. The increasing in UCS results due to stabilizing the materials by CKD increased the ability to use the CKD as alternative material for Portland cement.

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The road networks in Iraq suffer from the increase in the proportion of highly carriage trucks and vehicle growth rates, which requires improving the layer’s characteristics and using protective methods accomplished with suitable costs to achieve high quality and fewer cost treatments. This paper investigates the effect of modifying sand -gravel soil as a base layer by using cement or/ lime as a replacement to the original filler. The mechanical properties of the mix were evaluated based on compaction, CBR, and compression strength tests. The results for the CBR test suggested that there was an increase in bearing ratio when replacing a percent of filler by cement or lime as compared with the origin material, and the percent of replacement by cement or lime was 30% of origin filler. The results for the compression strength show that there is an increase with increasing percent of filler replacement by Cement, on the contrary, the Lime increase reveals a decrease in strength. The replacement with cement was better than that of lime. Lime should be used in less than 30% from point of view cost and strength. The findings of this paper suggested that adopting the method will result in decreasing the thickness of the pavement layer. The best results obtained when adopting 100% replacement by cement (10% by total weight) which gave the best reduction in the required thickness by about 62%. Regarding the lime use, the results revealed optimal percent of lime to be used is about 3% of total weight.