Mechanical Properties Of Composite Additives Modified Mortar

In cold saline-alkaline areas of China, denudation caused by salt corrosion, freezing and abrasion, is a prominent problem of concrete pavement. If there is no repair in time, it will lead to concrete pavement structural damage, so that affects the service life. Therefore, aiming at the denudation characteristics of concrete pavement in cold saline-alkaline areas, to develop a new concrete pavement repair material which adapts to the environment conditions is not only an urgent requirement for science and technology to repair the concrete pavement in cold saline-alkaline areas, but also has an important guiding significance for new concrete pavement engineering construction.Using the method of orthogonal test and single factor test, this paper applies different test plans to the surface mortar and the base mortar, particularly their mechanical properties are studied systematically. The water-binder ratio, cement-sand ratio, latex powder-5044N and silica fume are chosen as parameters of surface mortar. The mechanical properties of overlay repair mortar, mixed with latex powder and silica fume are studied with the method of orthogonal test. And the base mortar which acts as interfacial agent chooses water-binder ratio, cement-sand ratio, latex powder-5010N, antifoaming agent, silica fume, dispersing agent and methyl cellulose ether as parameters. Using orthogonal test and single factor test method to study the mechanical properties of interface agent mortar mixed with latex powder-5010N, antifoaming agent, silica fume and other polymers. Analyzing the mechanical properties of the composite additives such as bending strength, compression strength, bending-compression ratio, bonding strength, elasticity modulus and shrinking percentage, main conclusions are drawn as follows:(1) The workability of overlay repair mortar is optimal when the water-binder ratio is0.45, the cement-sand ratio is1:3, the content of silica fume is5%and the content of latex powder is15%.(2) The influence sequence of each factor for overlay repair mortar sinking height is latex powder, cement-sand ratio, silica fume and water-binder ratio. The sinking height increases with the increase of latex powder, which is significant. The content of silica fume also affects the sinking height, the latter firstly decreases and then increases with the increase of silica fume. Thus, to adjust overlay repair mortar sinking height should mainly control the content of latex powder.(3)The influence sequence of each factor for overlay repair mortar bending strength is latex powder, water-binder ratio, silica fume and cement-sand ratio. With the increase of the latex powder, the bending strength decreases, and it is significant. At3d age, the bending strength is lowest when the content of silica fume is2.5%, after2.5%, the bending strength increase. The influence of3d bending strength of cement-sand ratio is not significant. At28d age, bending strength decreases as latex powder increase, but it increases as silica fume increase.(4) The influence sequence of each factor for overlay repair mortar compression strength is latex powder, water-binder ratio, silica fume and cement-sand ratio. AT3d and28d age, the compression strength significantly decreases with the latex powder increases. At28d age, the compression strength increases as silica fume increases.(5) The abrasion resistance of mortar mixed with latex powder improves as a whole. The mortar with a15%content of latex powder5044N presents a lowest wear rate and a highest abrasion resistance. According to the mechanism of erosion damage, the internal force of mortar is shear stress under the flushing action. It enhances the adhesion stress between cement mortars and aggregates after the mixing of latex powder and silica fume, which boosts the ability of mortar to sustain the shear stress, thus improves the abrasion resistance of mortar.(6) All of the shrinkage curves of overlay repair mortar accord with the form of log function εt=aln (t)+b, and the correlation of regression fitting of each group of curve is significant.(7) When the content of latex powder ranges between0and4%, the bending strength of interface agent mortar increases as latex powder increases. The bending strength separately increases by30.3%and80.4%at3d and28d age when the content of latex powder is4%.When exceeds4%, the bending strength decreases as the latex powder increases, but all of them are higher than the mortar without latex powder. The latex powder helps improve the bending strength of interface agent mortar, which reaches the highest at the content of4%. But the compression strength of interface agent mortar decreases as latex powder increases in the whole range.(8) When the content of latex powder is under4%, the ratio of bending compressive strength improves significantly as it increases. When above6%, strength stops increasing. The latex powder can boost ratio of bending-compressive strength of interface agent mortar and improve its toughness.(9) The latex powder can significantly improve the bond performance. The latter increases as the former increases. At28d age, the bonding strength is0.52MPa without latex powder, when it reaches2%, the bonding strength increases by15.4%, when it reaches8%, the bonding strength increases to1.28MPa, which is1.46times of the mortar without latex powder.