Experimental Study On Reinforcement Of Concrete Base Material Of Existing Buildings By Using Penetration Method

Concrete structure has good mechanical performance and low cost,but with the increase of service life,concrete is prone to deterioration,strength reduction and other phenomena,so more and more at home and abroad began to invest in the reinforcement of old concrete structure.There were many researches on the reinforcement of concrete structures at home and abroad,but there were few researches on the strength enhancement of concrete substrates.As the strength of concrete substrates is the premise of strengthening concrete structures,it is urgent to find a strengthening method for concrete substrates.In this thesis,based on the reinforcing mechanism of permeable crystalline waterproofing material on concrete substrate,a new reinforcing method was put forward,that was,compensating calcium ion reinforcing method.Then through the reinforcing mechanism of silicate ions,the sodium silicate was modified.Then,based on the reinforcing mechanism of sodium silicate,the method of reinforcing tetraethyl orthosilicate(TEOS)was proposed.Tetraethyl orthosilicate(TEOS)was hydrolyzed by acid environment and water quantity calculation,which made it possible to strengthen concrete with tetraethyl orthosilicate.All the reinforcement methods in this thesis are aimed at the characteristics of low strength concrete with poor impermeability.By means of concrete cube compression test,concrete surface rebound test,PDE(Partial Differential Equation)toolbox numerical simulation,scanning electron microscope(SEM)test,this thesis also explored the improvement effect of these reinforcing liquids on the macroscopic mechanical properties and internal microstructure of concrete after reinforcement.The results are as follows.(1)Reinforcement of concrete after processing through the cube compressive strength test,found that four kinds of fluid of reinforcement on the compressive strength of concrete has different degrees of improvement,but also for the intensity of the lower the permeability of concrete reinforcing effect is better,the use of modified sodium silicate and are hydrolyzed ethyl silicate of concrete reinforcing effect is best.(2)Through the rebound test of reinforced concrete,it is found that the four reinforcing liquids have better enhancement effect on the surface strength of concrete.And the lifting effect is better than concrete cube compression test.(3)By using the finite element seepage theory and PDE toolbox in MATLAB,the seepage depth of various reinforcement methods is simulated and calculated.The results show that the penetration depth of the reinforcement method of permeable crystalline material and the method of compensating calcium ion is the largest,the penetration depth of the reinforcement method of tetraethyl orthosilicate is moderate,and the permeability of the modified sodium silicate is the worst.(4)Through the scanning electron microscope(SEM)test on reinforced concrete samples,it is found that the four reinforcing liquids have generated C-S-H or three-dimensional mesh polymer with Si-O-Si chain in the concrete,which can effectively close the pores in the concrete and improve the internal microstructure of the concrete.