Experimental Study On Effect Of MICP On Recycled Aggregate And Mechanical Properties Of Recycled Mortar

With the rise of urban construction increasingly,the number of building waste have also increased simultaneously.Consequently the two major problems,the disposal of building waste and the supply of building materials,should be solved urgently in China.On the one hand,the urban renewal,reconstruction generate a large number of construction waste every year,and now the general means of disposal is landfill.This method not only wastes huge manpower and material resources,but also occupies a large amount of land resources.On the other hand,the demand for building materials is huge in the field of Architecture.However,building materials are not renewable,excessive mining will cause damage to the natural environment,and now the principle of sustainable development.The use of waste concrete to prepare for recycled aggregates as a new type of green building materials,which can not only reduce the amount of construction waste emissions,but also protect natural resources.However,the original recycled aggregate has many disadvantages such as edges,aggregate surface adhesive mortar,making it impossible to get a more extensive promotion and application,preparation of mortar and natural aggregate concrete used to replace.In order to improve the utilization ratio and quality of recycled aggregate,it can be used in mortar and concrete.In this paper the microbial mineralization deposition(MICP)formation of calcium carbonate crystals in recycled aggregate surface and internal pore,thereby improving the basic properties of recycled aggregate and recycled aggregate preparation after treatment to improve mechanical properties of recycled mortar.Supported by the National Natural Science Foundation of China(51578342),this paper has carried out the following research works.Firstly,in the biological laboratory,two kinds of DSM8715 and H4 strains were used to study the mineralization activity of two strains under different conditions of bacteria concentration,temperature,pH value,calcium ion concentration and time.We can get the best conditions for mineralization:The concentration of bacteria was 10~8/ml,the temperature was 25?,the pH value was 10,the concentration of calcium ion was10g/L,and the time was 20 days and 15 days respectively.By comparing their mineralization activity,it is concluded that the mineralization activity of H4 strain is better than that of the strain under the same conditions.Microscopic analysis(SEM,XRD,TGA)of the precipitate was carried out to show that the precipitate was calcite type calcium carbonate.Secondly,through the study of the use of jaw crusher and disc shaping machine will be pre curing mortar crushing made of recycled mortar block,from the previous chapter of the bacteria liquid and nutrient solution for the regeneration of mortar block immersion and spray two treatment methods.The study found that by jaw crusher two crushing by recycled aggregate disc shaping machine processing compared with the specifications of microbial treatment of recycled aggregate.When the untreated recycled aggregate is treated with the nutrient solution,compared with the recycled aggregate treated by different strains of microorganisms,it can be concluded that the basic properties of the recycled aggregate after the treatment of different microorganisms are significantly improved.While the use of spray treatment better than soaking treatment,and obtains the H4 strain in DSM8715 strain than participation effect.Thirdly,the last chapter draws the conclusion,this chapter studies 0.5,0.35different water cement ratio,cement sand ratio is determined in the premise of effect of preparation and performance of recycled mortar and mechanical performance test with recycled fine aggregate microorganisms before and after the treatment of recycled mortar.It can be concluded that all treated sedimentary microbial mineralization after recycled fine aggregate preparation of recycled mortar not only in the working performance and mechanical properties are far more than without any treatment after regeneration of fine aggregate mortar prepared under the same conditions,the spray treatment is still better than soaking treatment.The preparation of H4 strain mixed bacteria liquid nutrient solution preparation and mechanical properties of recycled mortar work performance is better than that of DSM8715 strain of bacteria liquid nutrient solution preparation and mechanical performance of recycled mortar work performance.