Effect Of Multiple Ions On Chloride Ion Transport In Mortar Under Marine Environment

The corrsion of reinforcement caused be chloride diffusion is one of the man durability of reinforecement concrete structures.In the costal area and salt lake region,reinforcement concrete structrues are always under the attacke of chloride diffusion coupled with sulfate attack.The deposied products induced by sulfate attack will change the inner microstructure of concrete and cement mortar,which further influences the progress of chloride ingress.The current research on the coupled attack mechanism of chloride ion and sulfate ion is limited.Therefore,it is prequiste to conduct the research on the diffusion rule of chloride ions under the influence of sulfate attack,which is significant to the durability of reinforcement concrete structures in actual application conditions.In this study,the distribution of chloride ions,mass loss ratio and mechanical properties were abopted as the macro indicators to reveal the macro performance of cement motar under the combined attack of chloride ions and sulfate ions.Some micro technology methods were used to express the micro structure of cement motar under attack.A chloride ions diffusion model,considering the influence of sulfate ions was established.Mass loss ratio,flexural strength,compressive strength,chloride ions distribution were adopted as the main macro indiactors to express the deterioration progress of cement mortar under coupled attack of chlori de ions and sulfate ions.The influence of water binder ratio,solution types and sulfate ion concentration on the chloride attack of cement motar was investuigated.The influence of water-binder ratio and concentration of sulfate ions on the diffusion pro cess of chloride ions was quantified by using the integral area of chloride ion distribution and chloride ion erosion depth.The time-varying model of integral area of chloride ions distribution was established.The Modified diffusion coefficient model of chloride ion,considering the influence of sulfate attack was proposed.SEM,XRD and X-CT were used to reveal the change of micro structure of cement mortar under coupled attack of chloride and sulfate ions.The influence of water binder ratio and sulfate ion concentration on the diffusion of chloride ion was revealed through the qualitative and quantitative analysis of AFT and gypsum.The pore parameters changing rule of cement mortar under coupled attack was studied.A three-dimensional geometric model of erosive mortar was established,and the variation of pore characteristic parameters with erosion erosion cycle was analyzed.The modified diffusion coefficient of chloride ion was proposed considering the influence of sulfate attack with the prespective of mass transfer relation,chemical activity influence,porosity change and solid-liquid equilibrium relation.The modified diffusion model of chloride ions under the influence of sulfate ions was established by using comsol.