Experimental Study On Soil Rapid Solidification Performance Of Two Cement-based Materials

In order to meet the needs of emergency rescue,rapid repair and reinforcement in water conservancy projects,it is necessary to find a suitable early-strength soil solidification agent for emergency rescue of canal foundation,slope protection and river bed.This study aimed at the characteristics of the low strength and poor curing performance of the current soil solidification agent.The strength and impermeability of the two inorganic material soil solidification agents?sulfoaluminate cement-based soil solidification agent and phosphate cement-based soil solidification agent?were studied through laboratory experiments.Based on laboratory experiments and test results,the adaptability of the two early-strength soil solidification agents to different types of soil and the feasibility of emergency rescue in water conservancy projects were evaluated.In the beginning of this study,we searched for the optimal mix ratio of soil solidifying agent to meet the requirements of early setting and early strength.Then we used the best formulation of cement for geotechnical tests to solidify four different grades of soil?poorly-graded sand,fine-grained sand,silty sand,low liquid limit clay?.In the experiment,according to the construction process,different mixed ratio?fluidity?samples of solidified soil were made.After curing with three different curing methods,we measured those compressive strength,flexural strength and permeability coefficient.The test results of sulfoaluminate cement-based soil solidification agent show that:?1?The compressive strength of sulfoaluminate cement-solidified soil is logarithmically related to age.The 1d strength can reach 70%?81%of the final strength,and the early strength effect is obvious.?2?At 5%cement content,the 1d strength of fine-grained sand can reach 5.1MPa,which meets the minimum requirement of the erosion resistance of solidified soil?4MPa?;poorly-graded sand can meet the requirements in 3d;Low liquid limit clay cannot meet the requirements within 7 days.?3?At a cement content of 10%,the solidification strength of fine-grained sand and silty sand can meet the requirement in 3h;the strength of the poorly-graded sand and low liquid limit clay solidified soil can meet the requirement in 1d.?4?At 10%cement content,the permeability coefficients of the four solidified soils are all higher than 10^-7m/s,which can meet the anti-seepage requirements of general water conservancy facilities.Therefore,a comprehensive assessment shows that the10%cement content has good soil adaptability and solidification effect,which can meet the emergency rescue and reinforcement needs of general water conservancy facilities.The test results of phosphate cement-based soil solidification agent show:?1?The optimal formula of magnesium phosphate cement-based soil curing agent is:P/M value is 1:3,the amount of borax is 10%,and the fineness of magnesium oxide should be about 200m²/kg.?2?At 10%cement content,the strength of phosphate cement solidified soil is lower than that of sulfoaluminate cement solidified soil;the strength of the three solidified soils meets the requirements for more than 3d.?3?When the cement content reaches 20%,the strength of the poorly-grades sand,fine-grained sand and silty sand can meet the requirements in 3h.In addition,considering the poor water resistance of phosphate cement cured soil,it is not suitable for emergency reinforcement in water environment.Its early strength characteristics are more suitable for rapid repair and structural reinforcement of cracks and erosion of concrete buildings.