商品混凝土收缩性能的试验研究

【作者】 吕艳梅；

【导师】 刘立新； 徐有邻；

【作者基本信息】 郑州大学 ， 结构工程， 2004， 硕士

【摘要】 商品混凝土以其进度快、质量好、劳力省、消耗低、技术先进、现场文明等诸多优点，已成为城市建筑业不可缺少的组成部分。然而，由于商品混凝土使用要求流动性大，配合比中水泥和细骨料比例偏大、粗骨料比例偏小，使得商品混凝土收缩偏大，容易出现裂缝。据统计，在混凝土结构的裂缝中，有70％以上为非荷载裂缝，其中就包括混凝土材料本身在收缩过程中产生的裂缝。如何找出混凝土的收缩机理，从而更好的控制收缩裂缝，是有待解决的问题。 本文通过连续180天对24组99个商品混凝工收缩试件收缩应变的量测，分析得出商品混凝土在标准条件下的收缩应变计算公式，利用多系数叠加法分析给出非标准条件商品混凝土的多系数收缩应变计算公式，并根据本试验数据、参考国内外收缩试验资料，给出各影响系数的确定方法。 此外将本文所给收缩应变计算公式与ACI收缩公式、Trost收缩公式、中国建筑科学研究院收缩公式、王铁梦收缩公式进行分析比较，证明本文所给公式更适用于商品混凝土。 配筋商品混凝土收缩试件收缩时，混凝土受拉，钢筋受压。利用拉压平衡和同条件下素商品混凝土试件和配筋商品混凝土试件的收缩差值，给出了商品混凝土时随收缩应力计算公式和以及商品混凝土时随弹性模量的计算公式，为控制商品混凝土收缩裂缝提供了依据。 最后，通过收缩机理研究分析，给出混凝土收缩的补偿控制措施。 本课题为国家混凝土结构设计规范第六批科研课题。更多还原

【Abstract】 Merchandise concrete with merit of accomplished quickly, good quality, spared manpower, low expend, state-of-art technology and civilized scene, has became the indispensable part in the civil architecture field. However, owing to the larger liquidity, the larger ratio of cement and fine aggregate in mixing proportion and the smaller ratio of coarse aggregate, merchandise concrete has larger shrinkage and emerges cracks easily. According to statistics, non-load cracks occupy more than 70 percent in all concrete structure cracks. So, how to find out the shrinkage reasons of merchandise concrete and control shrinkage cracks still to be solved problem.Through measured 24 groups 99 lumps of merchandise concrete shrinkage specimens’ shrinkage strain in series 180 days, this paper analyzed and worked out the shrinkage strain-time computing formula of merchandise concrete under standard condition. Shrinkage strain-time multi-coefficient computing formula of merchandise concrete under nonstandard conditions was gave out by using multi-coefficient superposition method, at the same time, each influence coefficients were offered basing this experiment dates and referencing shrinkage text material of home and abroad.Besides, the comparing and analyzing were proceeded both computing formula given by this paper and ACI formula, Trost formula, the Building Research Council of China formula and Wang Tie-meng formula, though which prove that the formula given by this paper was true of merchandise concrete.When merchandise concrete specimens placed steel bar shrank, concrete was tensioned and steel bar was pressed. Utilizing the equilibria of pull and press and the dispersion between placed and unplaced steel bar specimens, this paper put forward the shrinkage stress-time computing formula and elastic modulus-time computing formula of merchandise concrete that offered the reference for controlling merchandise concrete cracks.At last, based on the research and analyses, this paper gave the measures of compensating and controlling the merchandise concrete shrinkage.This research subject is the sixth passel subject of code for design of concrete structure.更多还原