Research on Preparation and Performance of a New Type Inorganic Anchoring Material
|Keywords||new type inorganic anchoring material post-embedding steel interface bonding length of anchoring|
Nowadays the appraiser, maintenance and reinforcement techniques have become important parts in field of modern civil engineering and have been highly regarded at home and abroad. At abroad the buildings’ maintenance and rebuilding has become an important part of construction. Generally speaking, civil engineering will gradually step from ’large-scale construction period’ to maintenance period.Post-embedding steel technique is a new type of building reinforcing and rebuilding technique with excellent technical advantages, the research development of which has become a very active part of modern building structure reinforcing and rebuilding techniques. Since the existed research hasn’t illuminated the failure form of post-embedded reinforcing steel bar bonding anchor and its mechanism, hasn’t systematic research on factors influencing the function of post-embedded reinforcing steel bar bonding anchor, and also failed to test on the long period validity of post-embedded reinforcing steel bar bonding anchor, it is very unfavorable for the spread and application of post-embedding technique. In the meantime, the fact that the present post-embedding anchoring material is of few kinds, high prices and still-to-be-improved performance has become the bottleneck of the post-embedding technique’s development, which has restricted its further application and development. Therefore, it is of great importance to develop a new type high-performance inorganic anchoring material with reasonable price and improved performance.In the study, a new kind inorganic anchoring material was developed, which consisted of special binder and aggregate, the former is made from clinker, blast furnace slag and compound admixture, and the later is superfine sand. Effects of the factors such as clinker/slag, binder/sand, solution/binder and constituent of solution on the strength, set-time and contraction of the matrix made from the anchoring material were studied. Durability’s of the material such as permeability, heat-resistance, carbonation and steel bar-protection were tested. The bonding characters between anchoring material matrix and post-embedding steel bar, the matrix and the concrete structures were studied. The failure mechanism of anchoring system was analysed, and the failure form and chitical length of anchoring steel bar were determined, factors influencing the properities of anchoring were discussed, and engineering application was carried cent. On the basis of<WP=6>above mentioned, it can conclude as follows:①The new anchoring material has the character of high strength, high early strength and fast-setting, strength of the matrix at age of 10h and 365-day could reach to 26.5MPa and 144.0MPa respectively, the initial set of the paste is in the range of 40min-3h. and interval between initial set and finial set is lower than 15min. In the saturated meadium, the matrix exhibites expansion, and expansion ratio is lower than 0.5%.②The material could meet the require mart for anchoring of concrete constructure designed strength grade in the range of C60~C100 by way of adjusting the composition of admixture.③The material has excellent durability such as heat-resistance, impermeability and steel-protection.④The limit Load of the post-embedding steel ban is determined by the bonding strength between concrete and anchoring matrix, when length of embedding steel bar is enough, and the interface is the poor link. ⑤The critical Length of embedding steel bar is controlled by the factors such as flexture strength of the matrix, thickness of matrix covering on surface of steel ban, interval of the steel bar, diameter and surface character of steel bar, and the efficient embedding Length of steel bar is in the range of 10d~15d (d-diameter) of steel bar in most case.