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低水胶比湿喷混凝土的可喷性能研究
作者：王巧1，2，3，王祖琦1，3，宋普涛1，3，周永祥1，3，杨长辉2
（1.中国建筑科学研究院有限公司，北京 100013；2.重庆大学 材料科学与工程学院，重庆 400045；
3.建筑安全与环境国家重点实验室，北京 100013）
摘要：喷射混凝土（湿喷法）通常以C30及以下强度等级为主，难以满足某些修补及隧道工程对高强喷射混凝土的需求。高强混凝土具有水胶比低、粘度大等特点，采用喷射施工的难度更大。研究了低水胶比混凝土的净浆流变性能、可输送性能，并采用小型湿喷机验证了混凝土的可喷射性能。结果表明：新拌混凝土的可变形能力值Γ越接近7，其可输送性能越理想；一次喷射厚度随着拌合物屈服应力值τ的增大而增大，但塑性粘度η与喷射厚度没有明显的关系；C50混凝土中掺入82 kg/m3降粘增强剂可明显提高湿喷混凝土的可喷射性，回弹率降至6.5%，一次喷射厚度为160 mm。
关键词：低水胶比；湿喷混凝土；可喷性；回弹率
中图分类号：TU528.53 文献标识码：A 文章编号：1001-702X（2018）06-0001-04
Study on the shootability of wet-mix shotcrete in low water-binder ratio
WANG Qiao1，2，3，WANG Zuqi1，3，SONG Putao1，3，ZHOU Yongxiang1，3，YANG Changhui2
（1.China Academy of Building Research Co. Ltd.，Beijing 100013，China；
2.College of Materials Science and Engineering of Chongqing University，Chongqing 400045，China；
3.National Key Laboratory for Building Safety and Environment，Beijing 100013，China）
Abstract：The general strength degree of wet-mix sprayed concrete is still as low as C30 or below，which can not satisfy the high strength requirement of devastated concrete repair or tunnel engineering. Concrete with high strength has a feature containing low water-binder ratio，high viscosity，which usually results in hard placement in the process of spraying. According to this paper，the rheology of paste on low water-binder ratio concrete and pumpability were studied respectively，and also the crucial performance of shootability of concrete was verified successfully by using small type spraying machine. The test results showed that the fresh concrete with a deformability Γ closer to 7 had relatively more appropriate pumpability；and build-up thickness tended to increase as the yield value τ became greater，while，the viscosity η had a non-significant effect on the build-up thickness. Adding 82 kg/m3 viscosity reducer in C50 concrete can obviously enhance shootability of wet-mix shotcrete，with a figure of 6.5% low reboud rate and 160 mm build-up thickness in a single pass.
Key words：low water-binder ratio，wet-mix shotcrete，shootability，rebound rate