Experimental Study On Strength And Water Stability Of Sea Sand Composite Solidified Silty Soil Method

Utilizing the silt in coastal cities in C hina as a resource can not only reduce environmental pollution but also produce huge economic benefits.According to a test section of a solidified sludge road in N ingbo,it was found that traditional solidified sludge had problems such as shrinkage,cracking and insufficient water stability in actual projects,which limited the scale of solidified sludge and needed to enhance the quality of solidified sludge.Sea sand is a rich natural sand and gravel resource in coastal cities in C hina.Due to its excellent strength characteristics and water stability,sea sand composite solidified silt is a good choice to replace traditional fillers.If the area’s own sea sand can be applied to the improvement of solidified silt,short-distance transportation and large-scale application can be realized.Sand composite solidified silt refers to a solidified soil mixture in which a suitable amount of sea sand or river sand is added as an aggregate on the basis of the traditional solidifying agent of cement and lime.As a medium coupling body of sand and soil,it is different from traditional solidified silt.In order to explore the feasibility of sea sand composite traditional solidified silt,firstly,the physical and mechanical strength change law was studied through single mixing and orthogonal experiment.On this basis,the water stability test was improved,and the water stability index and influencing factors were studied from multiple angles.It is expected to provide reference for the application of sea sand composite solidified silt in coastal cities such as Ningbo.The main conclusions are as follows:(1)The compaction test results show that the optimal moisture content and maximum dry density of sea sand and river sand are basically the same.The optimal moisture content of sea sand composite solidified silt decreases with the increase of sand content.However,the range of variation is small,and the maximum dry density increases with the increase of the sand content,which is conducive to compaction during construction.(2)The 7d unconfined compressive strength of the consolidated solidified silt after river sand and sea sand has been significantly improved.When the sand content is between 10%-15%,the 7d unconfined compressive strength of the consolidated solidified silt of sea sand,the maximum can reach 1.40 MPa,and the composite solidified silt of river sand can reach 1.35 MPa,which meets the requirements of the sub-base layer of the second and lower roads.And the orthogonality mechanical test analysis results show that the amount of sea sand,the degree of compaction,and the age are positively correlated with the compressive strength and splitting strength of the sea sand composite solidified silt.The order of priority is:age>compaction degree>The content of sea sand and the three factors have significant effects on the unconfined compressive strength of solidified silt.(3)Under different water disturbance conditions,the sea sand content,compaction degree,and age have different effects on the water stability of solidified silt,but the three factors and water stability all show positive correlation changes.And the test proved that the water stability of the solidified sludge is related to its water retention capacity,and the precipitation of calcium hydroxide crystals in the mixture is one of the important reasons for the decrease of the strength of the solidified sludge.In the actual project,adding about 10% of sea sand can increase the water stability of traditional cement and lime-solidified silt by about 30%.