Effect Of Microbial Self Repairing Agents With Different Calcium Sources On Self Repairing Performance Of Concrete

In order to solve the problem that the micro cracks produced by cement concrete are not easy to be found and manual repair needs to consume a lot of manpower,material and financial resources,this thesis uses the combination of self-healing particles and calcium source to form microbial self-healing agent to repair the cracks.The self-healing particles are composed of carrier diatomite and Bacillus Pasteurella bacterial solution.The effects of carrier diatomite and two different calcium sources,calcium chloride and calcium bicarbonate,on the mechanical properties and durability of self-healing concrete were studied.After the artificial induced crack is repaired,the repair effect of the crack filler is analyzed by apparent analysis,scanning electron microscope analysis and XRD composition analysis.The compressive strength recovery rate of the self-healing specimen after 28 days of crack repair is measured,and the conclusions are as follows:1)The two calcium sources can significantly improve the splitting strength and compressive strength of self-healing specimens,and calcium chloride as calcium source has a greater effect on the splitting strength and compressive strength of self-healing specimens.The compressive strength and splitting strength of self-healing specimens with carrier are higher than those without carrier.2)The brittleness of self-healing concrete with different calcium sources is analyzed.The brittleness of self-healing concrete with calcium bicarbonate as calcium source is improved.With the increase of water cement ratio,the brittleness of self-healing concrete with calcium chloride as calcium source does not decrease significantly.3)For the specimen with calcium chloride as calcium source,the crack is completely repaired,and the maximum width can reach 1mm.For the specimen with calcium bicarbonate as calcium source,the crack is completely repaired,and the maximum width can reach 1.2mm.Comparing the crack repair effect of self-healing specimens with and without carrier,it is found that the self-healing specimens with carrier can completely repair the cracks less than 1mm within 7 days,while for the specimens directly adding microorganisms to cement concrete without carrier protection,the cracks have not been repaired within 7 days,and some cracks less than 1mm can be repaired within 28 days.4)Adding calcium source will improve the durability of self repairing concrete,and there is little difference between the two calcium sources on the durability of concrete.The self-healing test piece containing carrier has better durability.5)The morphology of Crack Filler with different calcium sources is different.The crack filler with calcium chloride as calcium source is square and needle,while the crack filler with calcium bicarbonate as calcium source is only square.The components are a large amount of calcite calcium carbonate and a small amount of aragonite calcium carbonate.The content of the products of the two calcium sources is almost the same and the crystallinity is good.6)Although the compressive strength of the repaired specimen decreases slightly,it is still higher than the set strength requirements,and the compressive strength is higher than that of the blank specimen.The self repair effect of calcium chloride as calcium source is better than that of calcium bicarbonate as calcium source.