Mixture Ratio Design Of Soil Curing Agent Based On Solid Waste And Study On Curing Performance Of Solidified Soil

Silty sand is widely distributed in the alluvial plain of the Yellow River in Shandong Province.When the silt is used as a road filler,it often cannot meet the strength requirements of the roadbed and the subbase.After curing,it can be used as a roadbed and subbase filler.On the other hand,Shandong The industrial development process in the region has accelerated,and industrial wastes have also increased year by year.Their accumulation has occupied a large area of land and caused serious damage to the ecological environment.Solid wastes such as slag,fly ash and desulfurized gypsum in industrial waste have potential gelling activity,which can strengthen the soil and improve the mechanical properties of the soil.The soil after reinforcement can be used in all grades of highway roadbed and subgrade.And the paving of the grassroots.In order to explore the feasibility of applying solid waste such as slag,fly ash and gypsum to road engineering,orthogonal test and controlled variable test method were used to study the content and ratio of slag,fly ash and desulfurization gypsum.The influence law of unconfined compressive strength of solidified soil 7d,orthogonal test shows that the best ratio of curing agent is ordinary Portland cement:slag:fly ash:gypsum= 30:44:15:11;Ordinary Portland cement:slag:fly ash:gypsum = 40:38:13:9;iron aluminate cement:ordinary Portland cement:slag:fly ash:gypsum = 9:291:440:150:110.In order to further study the effect of soil curing agent dosage and curing age on the performance of solidified soil,the solidified soil with 4%,6%,8%and 10%curing agent was prepared,and the solidified soil was tested without limitation.The effects of curing agent dosage and delay time on the unconfined compressive strength of solidified soil at 7d and 28d were studied with the change of compressive strength and splitting strength with the age of curing(7d,28d,90d,180d).The test results show that the unconfined compressive strength and splitting strength of the solidified soil increase with the increase of the curing agent dosage,and increase with the growth of the curing age.With the increase of the construction delay time,the sample has no lateral compression resistance.The strength gradually decreased.When the delay was 8h,the strength of the solidified soil in the B3 group was the lowest,which was 0.84MPa,which still met the strength requirement of the subgrade of the highway subgrade(>0.8MPa).The effects of curing agent dosage and curing soil curing age on the temperature shrinkage performance,water stability performance and dry-wet cycle performance of solidified soil were studied.The results show that the temperature shrinkage coefficient of the three groups of solidified soil increases with temperature.the dry-wet cycle coefficient of solidified soil increases with the increase of curing agent dosage,and the dry-wet cycle coefficient decreases with the increase of curing age.The decrease in the coefficient of wet circulation is reduced;the stability coefficient of solidified soil water is less than 1.The microstructure and chemical composition of the solidified hydrated products with different curing agents were studied by scanning electron microscopy.The SEM experiments showed that the soil hydrating products mainly contained fibrous and networked hydrated calcium silicate gels and needles.Rod-shaped ettringite crystals;the hydrating product of the curing agent can fill,compact,and bond the soil particles in a loose state,thereby enhancing the engineering performance of the soil.X-ray Diffraction(XRD)test found that when the amount of curing agent increased,the peaks of Aft,C-S-H and C-A-H increased significantly,and the peaks of SiO2,C2S and Al2O3 increased slightly.When the curing soil age increased,Aft,The peak value of CSH increased significantly,and the peaks of SiO2.C2S,Al2O3,and C-A-H decreased,indicating that the curing agent continued to hydrate with time.When sulphoaluminate cement was used,the peaks of Aft.C-S-H,and C-A-H increased significantly.The peaks of SiO2,C2S,and Al2O3 gradually become smaller.