Experimental Research On Improving Impermeability Of Self-curing Mortar

It is often necessary to use vertical cut-off walls to remedy the early completion of landfills that have not taken any seepage control measures or imperfectly impermeable old landfills.Self-curing mortar cut-off wall is a vertical impervious wall,with a low elastic modulus,adapting to the foundation deformation ability,simple construction technology,low cost and other advantages.It is often used in the environmental protection projects.But in some practical applications of self-curing mortar,it is often showed that the wall of the permeability coefficient can not match the design requirements of the situation.Therefore,there is guiding significance to improve the anti-seepage properties of self-coagulated mortar consolidation body and to study its mechanical properties and micro-mechanism.It is carried from the macro and micro level research,experimental research seepage performance,mechanical properties and pore structure of the interior of the mixing ratio of self-setting mortar to improve the barrier properties since setting mortar solidification body.It also has been optimized with the ratio,laboratory experiments in this paper.The main research contents are as follows:(1)Three different mix ratios were designed for different types and quantities of self-curing raw materials.The permeation coefficients of 7d and 28 d were determined by ST55-2 modified osmometer.The bentonite,fly ash and the alkali activator can affect the permeability coefficient.The effect of age on seepage resistance was also studied.The optimum formulation was obtained.The optimum dosage of fly ash was 230~250g/1000 g water,the permeability coefficient of up to 1.99×10-7cm/s.Fly ash in the environment of alkali activator,the permeability coefficient will be reduced.In addition,permeability coefficient1×10-7cm/s belowthe self-curing mortar consolidation body can be got with 1000 g water,NaOH and Na2SiO3 dosage of 50 g,bentonite dosage 180~200g,fly ash dosage 350 g,cement 200 g.The 28 d curing age of the consolidation of the seepage resistance is better than 7d curing age of which.(2)The test piece was prepared according to the optimized mix proportion,and the stress-strain curve and compressive strength and deformation modulus of the solidified body were obtained by the electronic universal testing machine.The strength was up to 2.42 MPa and deformation modulus was up to 60.15 MPa.(3)The solid structure of the solidified body was analyzed by electron microscopy,and the pore structure of the solidified body was analyzed by ToupView software.The critical pore size of the self-coagulated cement consolidation was about 23~80μm,The reaction mechanism of cement-bentonite and the model of fly ash susceptibility to alkali were briefly analyzed.The relationship between the pore and impermeability of the solidified body was analyzed and discussed.