Fine Numerical Simulation And Experimental Study Of Chloride Corrosion Of Self-compacting Concrete

Chloride ingress concrete structures is an important and difficult problem in concrete durability field.In recent years,it is urgent and important to study the durability of self-compacting concrete,especially with the wide application of self-compacting concrete in highways and bridges.With the development of the high-performance concrete materials,active mineral admixture and super plasticizer were used to compound high performance to conserve the energy and save the raw materials,and this topic has been a construction issue of the world.Meanwhile.Fly ash,Blast-Furnace slag.Silica fume and other active minerals are always used as admixtures of concrete.Because the mechanism related the corrosion of concrete structures by chloride is not clear,and the research on the durability of the corrosion of concrete structures by chloride is mainly through the experimental study.At home and abroad,the study on the durability of self-compacting concrete is less,let alone the study related the self-compacting concrete with mineral admixture.Based on the existing research results,the main research works of this paper are as follow s:Firstly,experimental study of chloride solution corrosion on self-compacting concrete and experimental study of clhloride spray corrosion on self-compacting concrete were carried out.During the two tests,the ratio of water to binder,the kind of admixtures,the amount of admixture and the composition of chloride solution were taken as variables.Three kinds of mineral admixtures(Fly ash,Blast-Furnace slag and Silica fume)were selected for the experiment,at the same time,nine kinds of self-compacting concrete were used in these tests.Each kind of self-compacting concrete specimens with the same composition contains only one kind of admixture,for self-compacting concrete specimens with the same admixture,two different blending amounts were used to ensure eight kinds of self-compacting concrete are different.Meanwhile,self-compacting concrete specimens without mineral admixture was used as the control group.In the process of test,self-compacting concrete specimens were carried out from the test device at every 30 days.Then the content of free chloride ions and the content of total chlorine ions at different depths inside self-compacting concrete specimens and the cube compressive strength were measured to study the durability of self-compacting concrete.Secondly,the chloride diffusion coefficient of self-compacting concrete was measured with RCM method,and self-compacting concrete specimens were immersed by NaCl solution.From the self-compacting concrete cylinder specimens immersed in NaCl solution,the chloride diffusion coefficient of self-compacting concrete was measured at every 30 days.Then,nine different fitting curves of the chloride diffusion coefficient of self-compacting concrete were obtained by Matlab.and the chloride diffusivity of concrete at different ages could be predicted.Thus,the durability of self-compacting concrete affected by mineral admixtures and mineral admixtures content was measured based on the nine curves.Finally,the partial differential equations with reaction term were achieved based on the Fick's second law.considering the dynamic equilibrium adsorption and release of chloride ion in concrete.The model of concrete aggregate is obtained by Matlab based on the delivery of three graded aggregate and the probability density function of the pore.Then the multiscale refined numerical model of self-compacting concrete was established by Matlab based on Abaqus.At last,the rationality and accuracy of the refined numerical model was verified by comparing the calculated results with experiment results.