Research On Properties And Mechanism Of Sulphoaluminate Cement Solidified Soil

At present,the soil solidified by ordinary Portland cement has the defects of low strength,large deformation,poor water stability and difficulty in quickly hardening into structural materials,which makes it difficult to meet the requirements of subgrade filling engineering under certain specific conditions.Sulphoaluminate cement independently developed by China has the advantages of fast setting and hardening,high early strength,good volume stability and low carbon emission in the production process.Using its specific properties can effectively solve the defects of conventional cement solidified soil.Therefore,with the continuous deepening of research on sulphoaluminate cement,its advantages in rapid hardening of soil with high strength and reduction of carbon emissions will gradually be paid attention to,and it will also have more and more extensive application prospects in engineering fields such as subgrade filling solidification.Firstly,this paper studies the macro physical and mechanical properties of sulphoaluminate cement solidified soil through unconfined compressive strength test.Hydrated lime and nano-SiO₂ materials were mixed into sulphoaluminate cement solidified soil singly or in combination,and the compressive strength at 3d,7d and 28d ages were measured respectively.The influence law of different mixing ratio of two kinds additive agent on the compressive strength of solidified soil is analyzed,and the mixing ratio which has the most obvious influence on the compressive strength of solidified soil is obtained.The test results show that hydrated lime can effectively improve the early strength of solidified soil than nano-SiO2 better.Secondly,this paper chooses C,G1,S2 and M2 solidified soils which have the most obvious influence on the compressive strength,studies the phase composition and the change rule of relative content of solidified soil samples at different ages and mix proportions through X-ray diffraction?XRD?test and thermogravimetric-differential thermal analysis test,and observes the mineral morphology and microstructure of solidified soil samples at 1d age through scanning electron microscope test.Based on this,the solidification mechanism of sulphoaluminate cement solidified soil is analyzed and studied,and the interrelation between the changes of macro mechanical properties and microstructure of solidified soil is discussed.The experimental results show that the essential reason for the improvement of macro physical and mechanical properties of solidified soil is the compactness of its microstructure framework.Finally,on the basis of F1 and F2 solidified soil test schemes,this paper uses unconfined compressive strength test and XRD to study the solidification effect of sulphoaluminate cement on soil with different organic matter content.The test results show that the macro physical and mechanical properties and phase composition of solidified soil will be affected by the change of humic acid content.The increase of humic acid content ratio will reduce the compressive strength of sulphoaluminate cement solidified soil and the hydration products of cement,but sulphoaluminate cement can still achieve relatively ideal solidification effect.