The Study Of The Mechanical Properties Of Polymer Cement Reinforced Concrete Structure Repair Reinforcing Materials

Due to unreasonable design, construction improper operation and other human factors, as well as water erosion, ice storms and other natural factors, many of our reinforced concrete buildings occur many security risks of structural damage. Reconstruction of these buildings is not only expensive, but will also cause huge economic losses of life and production because of building disabled. Therefore, it is very urgent maintenance of existing reinforced concrete buildings.This paper focuses on the mechanical properties of the reinforced concrete structure repair mortar. First determin the basis of the cementitious material ratio through study on the different cementitious system performance in repair mortar. Use dispersible polymer powders and methyl cellulose as a modifier additives, choose expanders, polypropylene fibers to inhibit the overall contraction of the mortar and select two different mineral admixture of fly ash, silica fume to single blending and multi-blending, in order to get the best content and ratio.Experimental study on modified additives (redispersible latex powder, cellulose ethers) mixing the mechanical properties of mortar. Doped redispersible powder can significantly improve the workability of the mortar and mechanical properties, and as its dosage increases, the adhesion between the particles of set cement mortar specimen also be improved. In three kinds of powder, the Wacker powder cement mortar has optimal effect. Doped cellulose ether dosage can improve water retention and workability of the mortar, and increase its flexibility, but with the increase of dosage, the compressive strength decreased significantly, flexural and tensile bond strength declined slightly. When powder and cellulose ether are doped, the mortar specimens performance than those in the doped powder or cellulose has certain improvement. Wherein the effect of mortar density, abrasion resistance, impact resistance and durability indicators are most obvious.Shrinkage and mechanical properties of polypropylene fiber and expansive agent mixing mortar are discussed. The mortar specimen incorporated with the polypropylene fiber has better water retention. With the increase of polypropylene fiber content, mortar shrinkage of the specimen is gradually decreased, flexural strength increased significantly, but had no significant effect on the compressive strength. However, when the polypropylene fiber content further increases, the effect of bonding strength is not obvious. With the increase of the dosage of expansive agent, mortar shrinkage decreases, mortar compressive, flexural and bond strength decreased with increasing dosage. Doped mortar expansion agent can make good wet curing shrinkage of mortar delayed, but has little effect on mortar shrinkage rate. More gentle with expanders increase in the dosage of mortar bond strength changes. No powder mortar has poor water retention, water can easily consumed by evaporation and hydration reaction, the role of the expansion agent to be restricted, the bonded tensile strength doesn’t greatly improved. Incorporated into the powder in a mortar, can effectively improve the water retentivity of mortar, expansion agent role more fully, higher tensile strength bond.Analysing water reducing agent on the performance of mortar specimens. Add the the super plasticizer can improve the fluidity of mortar, improve the performance of its work effectively, improve the bond strength in some extent, super plasticizer admixture will reduce the compressive strength.Respectively study the fly ash and silica fume on the properties of mortar. Fly ash mortar fluidity get a more substantial increase, and the mortar fluidity increases gradually with increasing dosage, mortar shear strength was significantly increased. Increase in fly ash content of the mortar compressive strength, flexural strength gradually decreases, the shrinkage gradually reduce mortar bond strength was significantly lower. With the increase of the silica fume, the fluidity of the cement mortar is significantly reduced. Mortar flexural strength, compressive strength are dramatically increased, especially the early strength improvement is very significant. Equal substituted silica fume cement, cement mortar shrinkage increased significantly.The mortar microstructure analysis by scanning electron microscopy shows that Mixed with admixtures can enable a large number of cement hydration early tiny crystals grow and filled pores, pore refinement and distribution more reasonable, and post-hydration of the cement paste can more fully the structure of hydration products closer, higher late strength. Provides a basis for the theoretical analysis.