Strength Model of Soda Residue Soil Considering Consolidation Stress and Structural Influence

Soda residue(SR)is a type of industrial waste produced in the soda process with the ammonia-soda method.Applying SR to backfilling solves the land occupation and environmental pollution problems in coastal areas and saves material costs for foundation engineering.The strength characteristics of soda residue soil(SRS)under different consolidation conditions are the key points to be solved in the engineering application of SRS.Triaxial compression tests were performed on the undisturbed SRS of Tianjin Port.The shear properties of SRS under different consolidation conditions were then discussed.Meanwhile,a structural strength model(SSM)based on Mohr-Coulomb theory was proposed.SSM reflects the influence of soil structure on undrained strength(Cu)and divides the Cu into the following two parts:friction strength(C_(uf))and original structural strength(C_(u0)).C_(uf)characterizes the magnitude of friction between soil particles,which is related to the consolidation stress.Meanwhile,C_(u0)represents the structural effect on soil strength,which is related to the soil deposition and consolidation processes.SSM was validated by the test data of undisturbed soils.Results reveal that the undisturbed soil generally had a certain C_(u0).Therefore,the SRS strength model was established by combining the experimental law of SRS with SSM.Error analysis shows that the SRS strength model can effectively predict the Cu of undisturbed SRS in Tianjin Port under different consolidation conditions.

Consolidation Mechanism of Chloride Ion in Soda Residue from Ammonia Soda Process Method

Soda residue-magnesium oxychloride cement is prepared with soda residue from ammonia soda process method,magnesium oxide and magnesium sulfate heptahydrate as main raw materials,and its consolidation mechanism of chloride ion is studied.The results show that the hydration products of soda residue-magnesium oxychloride cement are mainly 5-phase,gypsum and brucite,which exist in the matrix in needle rod shape,long plate shape and hexagonal plate shape,respectively.When the molar ratio of MgO/MgCl_(2) is 8:1,the concentration of MgSO_(4) is 29%,and the mass ratio of soda residue:magnesium oxide:magnesium sulfate heptahydrate is 45.8:36.4:17.8.The chloride ion consolidation effect of the sample is the best,and the chloride ion consolidation content of the 7 d sample is about 93%.The chloride ion consolidation content of the 28 d sample is about 96%.

Development of Soda Residue Concrete Expansion Agent

A new type of concrete expansion agent has been successfully developed for the first time in the world by utilizing an industrial waste residue soda residue and an industrial wasteliquor.Adding 3%-6% of the agent into Portland cement enables a shrinkage compensating concrete to be prepared.Mortar and concrete containing this expansion agent have better shrinkage compensating and mechanical properties.The raw materials component,production process,technical properties,micro analysis of mortar made with this expansion agent,mechanism of expansion and research results are described in this article.The experimental results show that the new type of concrete expansion agent accords with the standard and its main mineral component is xCaO ySO 3 zAl 2O 3.