Preparation And Application Of Shotconcrete With High Air Content

Spray shotcrete concrete action by covering the surface of the rock, the rock preventscontact with air to produce oxidation thereby preventing deterioration of the surroundingrock, but also to prevent the loss of soil particles and rock softening occurs as watermolecules, and thus the rock played a play rock effect, maintaining the inherent strength ofthe effect. In practical applications, due to the dusty dry shotcrete rebound higher defectphased out, wet spraying concrete pumping performance due to the conflict with theejection performance, slow development. So prepare a low rebound, high performanceshotcrete is important.This paper presents a high-entraining shotcrete, the influence of its gas content ofdifferent dosage of air-entraining agents, water-cement ratio, sand rate. According to theactual construction, combined with laboratory experiments analyzing the mixing time,standing time on the content and effects of vibration time, the optimal process parametersproposed by comparing the test, the air-entraining high springback shotcrete thickness ratioand a jet test; of high entraining hardened shotcrete test the strength and frost resistance,and scanning electron microscopy and micro-pore structure of the test from the point ofview; Finally, high jet entraining concrete construction technology.According to the study, concluded as follows:(1) By entraining high shotcrete materialcomposition studies have shown that air-entraining agent content, the higher the air contentof concrete; entraining agent in the same situation, sand The higher rate of gas introducedinto the more stable bubbles is relatively good; within a certain range, the morewater-cement ratio the greater the gas introduced; fly ash to reduce air entrainment playedthe role of the fly ash entraining concrete, air-entraining agent dosage should be relativelyincreased;(2) With the increase of mixing time, the gas content increases, but after morethan120s, lower gas content; standing time increases, the gas content constantly reduced,recommends no more than1h. With increasing vibration time, increasing gas content,including more than45s after the gas began under recommended vibration time should notexceed45s.(3) high-entraining shotcrete rebound rate of about12%; once jet thickness canreach170mm, both to meet regulatory requirements.(4) entraining jet hardened high strength concrete28d, although lower than the ordinary mixed coagulant acceleratedshotcrete, but can reach36MPa, meet regulatory requirements; entraining jet high frostresistance of concrete to accelerate significantly better than mixed coagulant Commonshotcrete.(5) before and after injection through SEM image analysis showed that highentraining jet sprayed concrete can effectively meet the performance and ejectionperformance pumping concrete construction; through the pore structure of the test, thepresence of high-entraining shotcrete diameter less than the vast majority of tiny bubbles200μm are harmless pores.(6) According to the study room, combined with the specificproject proposals for construction.