Preparation And Experimental Study Of Durable Lining Concrete With Carbonized Solid Waste

Due to the lack of concrete components,the anti cracking of concrete lining can be improved by adding admixtures.Aiming at the engineering problem of lining concrete carbonation cracking,a new type of solid waste concrete admixture was prepared by carbonation treatment technology,and used to improve the carbonation resistance of lining concrete.The main research contents are as follows:1)the carbonation treatment system was independently developed,and the reaction kinetics of typical industrial solid waste carbonation treatment was obtained by changing the carbonation process conditions.The results show that:1)the influence of the type,content and carbonization degree of the admixture on the mechanical strength,carbonization depth and pore size distribution of the cement paste is studied,and the carbonization parameters and the range of solid waste admixture content with the best anti carbonization performance are obtained;2)the influence of the carbonization degree and content of solid waste admixture on the compressive strength,carbonization depth,pore size distribution,pH value and carbon content of lining concrete is systematically analyzed Combined with micro analysis,the mechanism of enhancing the carbonation resistance of lining concrete by carbonized solid waste is obtained,and finally the concrete mix design method based on carbonation resistance is obtained.Based on the above research,some achievements have been made.(1)The carbonation process is that the basic calcium magnesium minerals in raw materials react with carbon dioxide to form calcium magnesium salt.Through fitting analysis,the carbonation kinetic equation is established:C element content=a+bt+cT+dP+eH-ft2-gH2,in which the influence degree of carbonation parameters is:pressure>time>humidity>temperature.After carbonization,the physicochemical properties of blast furnace slag particles change little,while the changes of fly ash and steel slag are large.Nano calcite particles are formed on the surface,and the surface is rough or particle aggregation occurs.(2)Carbonated blast furnace slag has little effect on the carbonation resistance of cement paste.Compared with the non carbonated control group,the carbonation resistance and compressive strength of the cement paste test block with carbonated fly ash and steel slag were improved.The carbonation depth of the cement paste test block with carbonated fly ash and steel slag was 1.2 mm and 1.25 mm respectively at 10%dosage,which were less than those of the corresponding non carbonated control group and cement control group.The compressive strength of cement paste with 10%carbonated fly ash is 24.5MPa,and that of cement paste with carbonated steel slag is 24.8MPa.(3)The effect of carbonized solid waste on the carbonation resistance of concrete has the best dosage of 10%,and carbonized blast furnace slag has no effect on the carbonation resistance of concrete.For the pH value(carbon content)in the carbonated area,the concrete mixed with fully carbonated steel slag/fly ash is less than(greater than)that in the non carbonated control group,which is contrary to the change rule in the non carbonated area.It is proved that carbonated fly ash and steel slag can improve the carbonation resistance of concrete.(4)Through the whole factor analysis and optimization,the anti carbonation design optimization equation of fly ash and steel slag concrete is obtained,which can be used as the basis for the selection of admixture dosage and carbonation degree.