摘要
为进一步提升喷射混凝土性能,在添加无碱液态速凝剂的基础上优先选取粉煤灰和聚丙烯纤维,通过开展凝结时间、抗压和抗折强度试验,研究喷射混凝土性能变化。结果表明:喷射混凝土中加入3%无碱型液体速凝剂,初凝时间、终凝时间均能满足标准要求;粉煤灰掺量增加,凝结时间呈正向变化趋势,但抗压、抗折强度反向变化,粉煤灰早期强度损失比后期强度损失大,考虑凝结时间和强度,粉煤灰掺量选择15%;聚丙烯纤维对抗压强度的影响是先增加后降低,抗折强度则一直有所提高;适量纤维在水泥砂浆中能均匀分布,起到连接的作用,缓解混凝土的破坏,但过量的纤维不易均匀分散,互相搭接阻碍了内部空气的排除,导致混凝土密实度降低;研制的分离式湿喷设备通过高压定量泵压送速凝剂至高压水管中,在喷头处与混凝土拌和料混合,喷射至受喷面,不会产生粉尘,回弹量可控制在12%左右,一次喷射厚度可达10 cm,可连续喷射3~5 h。操作简便、成本低廉、喷射效果显著,可满足一般工程的施工需要。
In order to further improve the performance of shotcrete,fly ash and polypropylene fiber are selected preferentially on the basis of adding alkali-free liquid accelerator,and the performance change of shotcrete is studied.The result shows that(1)the initial setting time and the final setting time can meet the standard requirements when 3%non-alkali liquid accelerator is added into the shotcrete;(2)with the increase of fly ash content,the setting time shows a positive trend,but the compressive strength and flexural strength change in the opposite direction,and the early strength loss of fly ash is greater than the late strength loss,considering the setting time and strength,the content of fly ash is 15%;(3)the effect of polypropylene fiber on compressive strength increases first and then decreases,but the flexural strength increases all the time;(4)proper amount of fiber can be evenly distributed in the cement mortar,play the role of connection,and ease the destruction of concrete,but the excess fiber is not easy to evenly disperse,lap each other hinders the removal of internal air,and the density of concrete is reduced;(5)the accelerator is pumped into the high-pressure water pipe by high-pressure fixed-quantity pump of separated wet spraying equipment,mixed with the concrete mixture at the nozzle,sprayed to the spray surface without dust,the rebound amount can be controlled at about 12%,the thickness of the first injection can be up to 10 cm,and it can be continuously injected for 3-5 h.The advantages of simple operation,low cost and remarkable spraying effect can meet the construction needs of general projects.
作者
柴明明
李世佳
杨飞雄
任鑫
CHAI Ming-ming;LI Shi-jia;YANG Fei-xiong;REN Xin(Beijing Xinqiao Technology Development Co.,Ltd.,Beijing 100088,China;Sichuan Yakang Expressway Co.,Ltd.,Chengdu Sichuan 610047,China)
出处
《公路交通科技》
CAS
CSCD
北大核心
2022年第S02期119-124,共6页
Journal of Highway and Transportation Research and Development
基金
四川省交通运输科技项目(2019-ZL-12)
关键词
隧道工程
性能提升
强度试验
喷射混凝土
分离式湿喷工艺
tunnel engineering
performance improvement
strength test
shotcrete
separated wet spraying process
作者简介
柴明明(1993-),女,河北衡水人,硕士.(1256767878@qq.com)
