Experimental Study On The Effect Of Humic Acid On Engineering Properties Of Cement Soil

The use of cement as a curing agent to reinforce the soil is a very effective method of ground treatment.It has been widely used in engineering practice.However,when using cement to reinforce the soil with a high organic content,the presence of organic matter.Resulting in unsatisfactory reinforcement effect.Therefore,the study and analysis of the effects of humic acid in humic acid on the engineering properties of soil and cement-soil complexes not only have strong theoretical value,but also have broad guiding significance for practical engineering.In this paper,samples of different cement incorporation ratio and humic acid incorporation ratio were artificially prepared by adding cement and humic acid to natural air-dried alluvial clay soil.Through laboratory mechanics experiments,the effects of humic acid incorporation,cement incorporation ratio,curing age on the engineering properties of soil and cement-soil composite were studied from a macro perspective.Based on the test results,the mechanism of the effects of humic acid and cement on soil and cement-soil composite was discussed and analyzed.Through research,this paper mainly draws the following conclusions:(1)With the same curing age,the unconfined compressive strength and residual strength of the alluvial clay soil decrease obviously with the gradual increase of humic acid in the soil.And the unconfined compressive strength shows a decreasing rule of fast first and then slow.When the content of humic acid in the soil is the same,the unconfined compressive strength and brittleness of the soil increase slightly with the growth of the curing age.Humic acid can also affect the thixotropy of soil.The higher the amount of humic acid in the soil,the lower its thixotropy.(2)When the cement mixing ratio is the same,the unconfined compressive strength and residual strength of the cement-soil composite decrease significantly with the gradual increase of the humic acid mixing amount.However,when the cement mixing ratio in the cement-soil composite is the same and less than 20%,its unconfined compressive strength shows a decreasing trend that increases quickly and then slowly as the amount of humic acid added increases.However,in a cement-soil composite with a cement mixing ratio of 25%,the unconfined compressive strengthand the amount of humic acid showed a linear decrease trend.In the case of the same amount of humic acid,the unconfined compressive strength of the cement-soil composite increases significantly with the gradual increase of the cement mixing ratio,in addition,as the cement mixing ratio gradually increased from 0% to 20%,the growth rate of the unconfined compressive strength of the cement-soil composite gradually increased,however,in the process of gradually increasing the cement incorporation ratio from 20% to 25%,the growth rate of the unconfined compressive strength of the cement-soil composite decreased significantly.In actual projects,when cement is used to strengthen the soil with a high organic matter content,blindly increasing the cement mixing ratio cannot meet the economic requirements of the project.(3)In the case of curing age and the same amount of humic acid,the softening depth of the cement-soil composite decreases significantly as the cement mixing ratio increases.Moreover,as the cement mixing ratio increased from 0% to 20%,the decreasing trend of the softening depth of the cement-soil composite gradually increased.However,in the process of increasing the cement incorporation ratio from20% to 25%,the decreasing trend of the softening depth of the cement-soil composite was significantly slowed down.In the case of curing age and the same cement incorporation ratio,the softening depth of the cement-soil composite increases significantly with the gradual increase of the humic acid incorporation.Under the condition that the cement mixing ratio and the humic acid mixing amount are the same,the softening depth of the cement-soil composite decreases slightly as the curing age increases.However,the reduction rate is related to the amount of humic acid incorporated in the cement-soil composite.The higher the amount of humic acid incorporated,the smaller the rate of decrease in the softening depth.