| Tire rubber is a waste in the field of Transportation Engineering and known as ’black pollution’.Dealing with silt subgrade is a technical problem to be solved urgently in traffic engineering construction.It is of great significance to reduce the pollution and improve the modification technology of silt subgrade when considering these two aspects together.In this paper,the engineering properties and modification mechanism of waste tire rubber modified soil were studied by using a variety of waste tire rubber as additives,cementas curing agent and silt in Xuzhou area of Jiangsu province as the object of reinforcement.Based on the combination of laboratory test and theoretical analysis,the main results are as follows:(1)The compaction test showed that the maximum dry density of the modified soil was significantly reduced after adding the waste tire rubber.At the same content of rubber,the incorporation of powder is more obvious on the maximum dry density decreases and strip has more influence on the maximum water content.Therefore,the waste tire modified soil has good light quality.And according to the analysis of the mechanism,it is found that the addition of rubber increases the compaction work and makes the compaction curve move towards the left.(2)Through the unconfined compression and direct shear test,it is found that with the addition of waste tire rubber,the unconfined compressive strength of the most samples decreases,and the addition of rubber has a certain inhibitory effect on the hydration of cement at the early age.The optimal dosage of the rubber strip is 5%and the strength of the modified soil is higher than that of the cement soil under this ratio.(3)Adding powder and strip can both increase the shear strength of the specimen,and the increase of shear strength is caused by both increasing C and the φ.(3)Through freeze-thaw cycle test,it is found that the strength of the waste rubber strip modified soil decreased after freeze-thaw cycles,and the lowest value was found after the sixth cycle.The results also show that the sample is most affected by the first stage of freeze-thaw cycle,and the variation of water content and dry density rea ches the peak value at this time.By studying the mechanism,the specimen porosity increases with rubber strip and this effect reduces the influence of water frost;Moreover,the elastic effect of the rubber strip also partly bears the expansion and contraction of water.In general,the modified soil has good freeze-thaw resistance. |
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