| The importance of expansion joints arises from their ability to facilitate construction and to minimize stresses from environmental changes by controlling cracking and by permitting vertical and horizontal movements. Expansion and contraction butt joints are regularly sealed by the placement and curing of an elastomeric adhesive sealant. Sealant plays important roles in the increase of service life and service property assurance of construction, due to its prevention of the rain water, sundries into the joint. The sealant used in the joints must be capable of withstanding repeated extension and compression as the temperatures change and the ideal characteristics of sealants should meet requirements, such as good elastic and adhesion properties, excellent weatherability and chemical durability. There are various types of joint sealants commercially available for use in the joint sealing, such as asphalt, polyurethanes and epoxies, and so on. Nevertheless, current durability with these joint materials is often too short to prevent sealing operations, because of the aging resistance and resistance to elements.In this study, the reason of the sealant failure was analyzed, and organosilicone material with ageing resistant and resistance to elements was proposed to be used as a sealant material. The accessory ingredients were added into the materials in order to meet the requirement of sealant better, and an organ silicone rubber as a sealant was prepared.1. The testing program was optimized from environmental and applied aspect. The preparation of reaction mechanism of SR was investigated, and the structure and properties of SR were presented. Effect of additives, such as fillers, platicizer and tackifier, chain extender on the properties of SR was investigated.2. The effect of filler modification on the dynamic property and its distribution in the SR was investigated. The mutual effect between the SR and the filler, and the mechanism of filler modification were investigated. The model of modified filler was built up. 4. Based on the discussion mention above, the optimized formula was put forward. The properties of SR, such as impermeability, mechanical, stability, fatigue property were discussed, and assessment indicator system of SR sealant was built up. The result indicated that the SR used as a sealant showed good stability, fatigue resistance.4. The mutual effect between the SR and the base material was investigated, based on the advanced interfical theory. The mechanism of the interface between the SR and the base material was revealed that it exist chemical bond, jogged mechanics and hydrogen bond. The good adhesive strength of the SR is attributed to the physical mechanics and chemical bond and the synergy.5. Silicone rubbers are built up from Si-O-Si bonds. Their resistance to moisture, excellent weatherability, thermal stability, oxidation resistance and low-temperature flexibility make this class of materials very attractive selection for use in the outdoor applications. In this study, the SR was applied in the joint sealing of the marine construction and the concrete pavement. Also, the SR was used to the crack maintenance of the asphalt concrete because of the outstanding property. The construction technology and specification was presented. |
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