【作者】 吴浪；

【导师】 宋固全；

【作者基本信息】 南昌大学 ， 固体力学， 2007， 硕士

【摘要】 国内外对于早龄期混凝土力学性能的试验研究比较少见，特别是在外加剂的影响，研究文献较少。因此，本文针对强度等级为C25的混凝土在高效减水剂、早强减水剂的不同掺量影响下，分别进行立方体抗压强度、劈裂抗拉强度和轴心抗拉强度随龄期增长规律的研究，并对抗拉试验进行有限元分析，为混凝土结构施工阶段的验算及裂缝控制提供依据。通过对7组立方体试块在4个龄期的抗压试验，拟合出了标准养护条件下不同龄期混凝土立方体强度统一计算公式，它不但可以应用到普通混凝土中，而且可以应用到掺外加剂混凝土强度的推算等方面，具有较好的适用性。混凝土的抗拉强度通常以劈裂抗拉试验这一间接测试混凝土抗拉强度的实验方法来代替。本文推荐的方法很好的解决了混凝土在轴心抗拉试验中的“对中”问题，且试件易于制作，费用低，试件与试验机装夹方便，模具能重复利用，同心度好，测量结果稳定可靠，建议推广使用。工程中混凝土抗拉强度大多数采用劈裂法，探明劈裂强度与轴心抗拉强度之间的关系及其随龄期的变化有着工程实际意义。本文通过大量实验得到了混凝土劈裂强度和轴心抗拉强度之间随龄期变化的关系。由于混凝土材料是非匀质、非线性的，脆性人工混合材料，力学性能较为复杂，且随时间而变化，性能指标的离散性很大。因此，以试验相关数据作为参数进行有限元分析，并和试验结果加以比较，以弥补试验的观测性较差的不足。更多还原

【Abstract】 Few experimental research have been done about the early age mechanicalproperties of concrete at home and abroad, especially with the influences ofadmixture. Therefore, here is a research on the effect of the different blending amountof high efficiency water reducer and early-strength water-reducing agent on thedeveloping rules with age of the cube compressive strength, the indirect tensilestrength and the direct tensile strength of C25 concrete, and finite element analysison tensile strength was done at the same time. It provides a basis of concretestructure or checking computations and the control of cracks during construction.As results of compressive tests for 7 groups of cubic specimens in 4 ages, aformula for computing the cubic compressive strength of concrete in different agesunder standard curing conditions was fitted, which coincides not only with theordinary concrete but also with the concrete with addictives for its suitability.The tensile strength of concrete is usually obtained by splitting test, which is anindirect method. The paper designs the experimental apparatus for concrete of thedirect tension, which resolves the difficulty of ensuring that the load is truly axial, atthe same time, the making of the specimens is easy and cheap. The method in thispaper which is used to measuring the direct tensile strength is suggested to furtherapplication.The splitting tensile method for the tensile strength of concrete is usually usedin structural applications, so there is great importance in the investigating the relationbetween the direct tensile strength and the splitting strength, which have beenobtained in this paper on the base of tests.Concrete is anisotropic、non-linear、brittle and time-dependent, its mechanismproperties is very complex, and performance index is very disperse. Therefore, finiteelement analysis based on the parameter of the experimental data, compared with theresults of experiment, will compensate the deficiency of experimental observation.更多还原