چكيده به لاتين
Soil improvement definition is related to the methods in order to enhancing mechanical properties of soil in order to strengthening it for construction. One of the methods for soil improvement is the addition of materials such as lime, cement or a variety of polymers that increase soil particles' adhesion to each other. Nowadays, in Iran utilization of soil improvement methods based on grout application has become commonplace. This indicates the need to optimize grout consumption. First objective of this research is to find a mix design that besides the high compressive strength, has a high flowability, so that it can be used for a variety of soil improvement applications such as deep soil mixing, jet-grouting, and other types of injections. Secondly, the feasibility of using seawater to produce grout is a matter of great economic importance for coastal areas. In this study, to make high-strength grout micro-silica and metakaolin were used. These additives were evaluated in three ratios of water to cement 1, 0/75 and 0/5 produced with tap water & seawater. In order to increase the grout strength, the water to cement ratio decreased (0/35 in this study has been selected) and superplasticizer has also been used. Rheological studies indicated that for obtaining the same viscosity of the grout with the water to cement ratio of 0/35 compared to that of 1, it is necessary to replace 7% of water with a superplasticizer in the mix. Results of compressive strength tests also showed that with water to cement ratio of 0/35 and using 7% of superplasticizer, the value of 69 MPa is the highest compressive strength that can be achieved at 28 days for control mixes. The compressive strength was decreased by adding micro-silica and metakaolin. Comparing to the control mix, using seawater in the mix with water to cement ratio of 1 decreased the compressive strength about 30%. Decreasing water to cement ratio in samples containing seawater mitigated this reduction until in water to cement ratio of 1, incorporating 7% of superplasticizer, the compressive strength enhanced compared to the mix produced with tap water. Generally, the highest compressive strength of mixes was around 79 MPa. This value attributed to the mix produced with seawater, superplasticizer and water to cement ratio of 0/35.
