【作者】 刘玮；

【导师】 王子明； 蒋荃；

【作者基本信息】 北京工业大学 ， 材料工程（专业学位）， 2016， 硕士

【摘要】 超平地面(超平地坪)是指通过激光整平机对新浇筑的混凝土进行摊铺整平并结合一定地坪施工工艺,达到某种特定使用需求的一种地坪。采用激光整平机取代传统的手动式整平施工,用激光来控制地面的水平度和平整度,从而做到真正意义上的超平地坪。由于激光整平地坪技术引进我国的时间还不长,施工技术多借鉴国外的施工规范。开展适用于我国国情的大面积激光整平机械摊铺的地坪混凝土研究十分必要。本研究将地坪混凝土分为砂浆部分和粗骨料两部分进行。首先研究了水胶比、胶砂比、减水剂和增粘剂对砂浆流动性、泌水率、强度和收缩的影响。采用VISKOMAT XL型混凝土-砂浆流变仪测量了砂浆的流变参数,探讨了各种因素对砂浆流变性能的影响。在此基础上,运用最大密度曲线理论对粗骨料进行级配调整,研究了砂浆富余系数对混凝土流动性和强度的影响。实验结果表明,在特定水胶比下,选择合理的胶砂比并通过减水剂来控制砂浆的流动度,将会大大降低砂浆泌水率。砂浆的屈服应力和塑性粘度随水胶比、胶砂比和减水剂的掺量提高而降低。当砂浆的屈服应力g值在50~200Nmm范围内,塑性粘度h值在1.8~4.0Nmm.min范围内时,砂浆具有一定流动性和较少泌水,是配制工作性良好的超平地坪混凝土用砂浆的适宜流变参数范围。砂浆的收缩率随胶砂比的提高而增大。当胶砂比一定时,砂浆的收缩率随水胶比的提高而增大。聚羧酸系高性能减水剂和增粘剂对砂浆收缩率的影响不明显。通过骨料最紧密堆积曲线对粗骨料进行级配调整,使粗骨料达到最大堆积密度从而降低浆体用量是一条可行的技术。混凝土的流动度和扩展度随着砂浆富余系数的增大而增大。当水胶比较高时,混凝土的强度会随砂浆富余系数的增大而降低。更多还原

【Abstract】 Super flat ground, namely "super flat floor", is made by high precision laser leveling machine for fresh concrete paving leveling and combined with a certain floor construction technology, to achieve particular use requirements of the floor. Using laser leveling machine rather than traditional manual type, can high precision control the levelness and flatness of the ground. In this way, the ground can achieve real super flat floor. Due to the short time of laser leveling floor technology imported in China, the construction process is carried out in accordance with the foreign method of construction. It is necessary to research the concrete for large area laser leveling machine paving floor which suitable for Chinese national conditions.This study was divided into two parts: the mortar part of concrete and coarse aggregate of concrete.We studied the influence of water cement ratio, cement sand ratio, water reducing agent on mortar liquidity, bleeding rate, the strength and shrinkage.on the basis of study the influence of VMA on mortar liquidity, bleeding rate and the shrinkage. In addition, we used the VISKOMAT XL concrete-mortar rheometer to measure mortar rheological parameter. This paper discussed the influence of water cement ratio, cement sand ratio, water reducing agent and VMA on mortar rheological properties. We regulated coarse aggregate gradation based on the theory of maximum density curve of aggregate and studied the influence of mortar extra coefficient on the slump,slump flow and compressive strength of concrete.The experimental results showed that under certain water cement ratio, choosed reasonable cement sand ratio and controlled cement mortar fluidity, which will greatly reduce the chance of mortar bleeding. When water cement ratio determined, mortar shrinkage ratio increased with the rise of the cement sand ratio. When cement sand ratio determined, mortar shrinkage ratio increased with the rise of cement sand ratio.The influence of water reducing agent on mortar shrinkage rate was not obvious. Adding VMA would not rise mortar shrinkage rate. Increased water cement ratio、 cement sand ratio or adding water reducing agent, yield stress and plastic viscosity of mortar reduced. Adding VMA, yield stress and plastic viscosity increased. In this area, the g value in 50 ~ 200 Nmm and h value in 1.8 ~ 4.0 Nmm·min, mortar had suitable liquidity and less bleeding. This mortar can be used to make floor concrete.It is a feasible technology to adjusted coarse aggregate gradation by the aggregate maximum density curve, which would maximized the coarse aggregate packing density so as to reduce the dosage of mortar. The slump and slump flow of concrete increased with the rise of mortar extra coefficient. When water cement ratio is higher, the concrete strength would decrease along with the augment of mortar extra coefficient.更多还原