| Epoxy materials have been widely used in structure repair and strengthening fortheir excellent adhesion and outstanding mechanical properties. Many related studiesand products focus too much on repairing and strengthening structures in dryconditions, and they are difficult to meet the requirements when used in wet andunderwater projects. To solve this problem, this paper studied epoxy mortar and epoxymodified cement mortar for use in wet and underwater conditions.The study of epoxy mortar discussed the evaluation methods of its bondingcapability, and the influences of materials and surface treatments on test results wereinvestigated. Underwater bonding properties of different curing agents and mixedcuring agents were studied, basic epoxy mortar recipes and curing agents mixingprinciples were concluded, and the performances of basic recipes epoxy mortar wereoptimized to arrive at final recipes. Results show that the underwater performances ofdifferent curing agents are very different, but a single curing agent is difficult to meetthe requirements. The mixing of different types of curing agent is an effective way toimprove the underwater performance of epoxy mortar, but there is a significantdifference in the effect of different mixing types. When using modified cycloaliphaticamine and phenolic amine mixing system, the underwater tension shear strength ofoptimized epoxy glue can reach20.1MPa, air tensile shear strength22.7MPa, airtensile strength41.6MPa, air compressive strength100.9MPa, elasticity modulus2.53GPa, and epoxy mortar underwater direct pull bonding strength4.31MPa withinterface damage in the form of base mortar cohesive damage. Optimized epoxymortar has excellent underwater bonding properties, with no considerable decline ofdirect pull bonding strength after being soaked in water for one year.The study of epoxy modified cement mortar discussed the influences of differentkinds of waterborne epoxy and different polymer binder ratios on polymer modifiedmortars, basic epoxy modified mortar recipes were given, and the influences of curingconditions on epoxy modified mortar were investigated. Styrene-butadiene epoxyblending modification and epoxy mixed with diluents were used as two methods tooptimize the overall performances of modified cement mortar. SEM, laser particle sizeanalyzer and surface tension meter were used to analyze the functions andmechanisms of waterborne epoxy in cement mortar. Results show that waterborne epoxy A2shows better modifying performance among six products, and reasonableA2modified cement mortar polymer binder ratio is15%, with compressive strength58.9MPa, flexural strength14.3MPa, wet interface direct pull bonding strengthgreater than2.5MPa and the base mortar cohesive damage. These mechanicalproperties have already been able to meet the requirements of grade I polymermodified cement mortar for strengthening important structures in wet condition.Curing conditions notably affect the mechanical properties of the epoxy modifiedmortar. Early natural curing condition is conducive to the bending and bondingstrength development of modified mortar. Styrene-butadiene and epoxy blendingmodified cement mortar effectively reduce polymer binder ratio in ensuring themechanical properties meet regulatory requirements, but no noticeable improvementin extending operating time. Reactive diluents will improve the workability andincrease the amount of time before initial setting, as well as improve the toughness ofmodified mortar. The flexural strength of modified mortar with diluents outer dosageof14%can reach20.4MPa, an increase of63%compared to modify mortar withoutdiluents. |
PDF Full Text Request