Study On Properties Of Microbial Self-Healing Rubber Concrete

The technology of microbial induced calcium carbonate precipitation(MICP)can be used to make self-healing concrete,which can automatically repair its own cracks as soon as they appear,so that the durability of concrete is improved and the maintenance cost is saved.In the process of preparing self-healing concrete,it is generally necessary to use certain carriers to fix the bacterial spores that are capable of mineralizing to produce calcium carbonate crystals,and then add carriers loaded with spores to the interior of concrete.The existing spore immobilization methods are generally expensive or complicated.In order to find a more suitable bacterial spore immobilization method and increase the crack resistance of self-healing concrete,this paper attempts to prepare self-repairing rubber concrete by using rubber particles to immobilize bacterial spores.In addition,this paper studies the preparation method of self-repairing rubber concrete,physical and mechanical properties and self-healing property of cracks through experimental research.The main work is as follows:(1)The preparation method of self-repairing rubber concrete was studied.The bacterial spores were immobilized in the pores of the rubber particles by using 4% sodium alginate solution as adsorbent,and the effect of this immobilization method on the growth and activity of mineralized bacteria was studied by experiments.The results show that using rubber particles as a kind of carrier of bacterial spores prolongs the adjustment period of bacterial growth without affecting their final activity.Therefore,it is feasible to prepare self-repairing concrete by using rubber particles to immobilize bacterial spores.Finally,in addition to preparing ordinary concrete,two kinds of rubber particles(with particle size of 1~3mm and 0.18~0.425mm)were used to configure two kinds of ordinary rubber concrete and two kinds of self-repairing rubber concrete.(2)The physical and mechanical properties of self-repairing rubber concrete were studied.The results show that the slump of self-repairing rubber concrete is much higher than that of ordinary concrete and ordinary rubber concrete.In the comparison of two kind of self-repairing rubber concretes with different rubber particle sizes,the self-repairing rubber concrete with large rubber particles has better performance.For example,it has a 28 d compressive strength of 24.3% and a tensile strength of 33.2% higher than that of the corresponding ordinary rubber concrete,and its tensile strength is 44.5% higher than that of ordinary concrete.However,due to the low degree of early hydration,its early crack resistance characteristic is not ideal.(3)The self-repairing property of cracks in self-repairing rubber concrete was studied.The results show that the self-repairing rubber concrete with large rubber particles is better than the self-repairing rubber concrete with small rubber particles.The maximum crack width that can be repaired is 0.86 mm,and the crack repair property has spatial and temporal differences,which are related to the density distribution of bacterial spores in concrete.The self-repairing rubber concrete prefabricated by the compression test has a strength recovery rate of 96%.The paper found that self-repairing rubber concrete not only had good crack resistance,but also can achieve cracks self-repair well,which greatly enhances the durability of self-repairing concrete and provides new ideas and methods for the research and application of self-repairing concrete.