Study On Properties Of Waterborne Epoxy Resin Emulsion Modified Cement Mortar

According to a lot of tests and theoretical analysis, the influence of waterborne epoxy resin emulsion on the properties of fresh cement mortar, the mechanical behavior and the durability of the hardened modified mortar has been investigated systematically in the paper. The thesis provides preliminary datum about developing new type mortar modified by high-performance polymer and enlarges its application in civil engineering.First of all, two kinds of waterborne epoxy resin emulsion had been mixed into the modified cement mortar respectively in order to observe their influence on the properties of fresh modified mortar. Experimental result indicated that both of the emulsions were in possession of water-reducing function. Meanwhile, because of the specific air entraining function by adding emulsion, the modified mortar's density reduced and its setting time shortened. It was obtained that the stirring mode was one of the main factors which had serious relations with modified mortar's air entraining effect, as well as various defoaming agents. What's more, compared to reference cement mortar, two kinds of the modified mortar's early mechanical strength decreased to a certain extent, but its later strength increased. In this thesis, the curing system of the CH emulsion modified mortar was also analysed and the optimal curing system in varying proportion of the mixed emulsion was put forward.Through the adhesive tensile strength test, the application of the CH emulsion modified mortar to the bonding reinforcement for concrete structure was investigated. Some factors affecting the bonding strength of CH emulsion modified mortar to old cement mortar were analyzed concretely, such as surface appearance of old mortar, method of interfacial treatment and interfacial roughness, interfacial agent, etc, and also involved in this paper was the bonding mechanism of the interface. The result demonstrated that perfect adhesion between the modified mortar and old cement mortar was formed under the dry surface appearance; The rougher was the surface of old mortar, the higher was the bonding force of the interface; Two interfacial agents were adopted in this paper: cement paste mixed with expanding agent and CH emulsion. Cement paste mixed with expanding agent could improve the bonding strengthen of the common cement mortar obviously, but it had unconspicuous effects on modified mortar. As for the CH emulsion, it made the bonding strength declined. Frost resistance is one of the primary indexes to reflect the durability of mortar and concrete. The repairing performance and bonding durability of new to old mortar under freeze-thaw cycle were studied in this dissertation. With quickly freeze-thaw testing, a number of factors affecting the bonding behavior of new to old mortar were investigated: cycles of freezing and thawing, method of interfacial treatment and interfacial roughness, interfacial agent, etc. It was found that the adhesive tensile strength was improved along with the increase of freeze-thaw cycles. It might be concerned with the maintenance process of hot water curing. Furthermore, the adhesive tensile strength was not obviously affected by interfacial roughness under the freeze-thaw cycles, the two interfacial agents did not do much good to the frost resistance of the mortar either.