Improving the Characteristics of Subgrade Soil Using Different Chemical Additives: Case Study Al-Nasiriya Soil

Abstract

The roads in the city of Nasiriya in southern Iraq suffer from problems that occur as a result of repeated vehicle loads or due to weak soil and lead to losing their performance and being out of service despite their construction for a very short period. The use of chemical additives to improve the subgrade widely worldwide and give strength and durability to the weak soil while the possibility of using chemical additives for the substrate in Al-Nasiriya is still practically limited. The study aimed to verify the use of chemical additives (cement, lime, and ferric chloride) and to know their effect on the properties of Al-Nasiriya soil. The results showed a clear improvement in the UCS test when using chemical additives, and then the optimal percentages of additives were determined and were 9%, 10%, and 2% respectively, in addition to knowing the effect of the curing period (1, 7 and 14) days on the results of the test. For the other tests (maximum dry density, CBR, swelling, and optimum moisture content) were verified for the optimal chemical percentages and it was observed that the CBR values increased and the swelling values decreased after treatment and soaking in water for all additives, while the compaction parameters had a different behavior between the materials additive used.