低强度高性能机制砂混凝土和易性的研究

发布时间：2018-02-03 19:53

本文关键词： 机制砂低强度高性能混凝土和易性配合比设计　出处：《西南交通大学》2013年硕士论文　论文类型：学位论文

【摘要】：机制砂是经过机械破碎、筛分而制成的,粒径小于4.75mm的岩石颗粒。与河砂不同,由于机制砂有颗粒较粗糙、棱角多、级配较差的特点,应用在中低强度等级混凝土中时,用水量相对较多,混凝土拌合物工作性差,容易泌水离析。机制砂各项技术指标由于生产技术不同而各异,因此要得到性能良好便于施工的的混凝土,就对配合比提出了更高的要求。因此探索机制砂的哪些特性对混凝土的和易性影响较大,以及对于不同特性的机制砂如何调整混凝土的配合比使得其和易性优良,这对工程应用有很大实际意义。本文主要目标是研究怎样配制出具有良好和易性的低强度高性能机制砂混凝土。主要研究内容有： (1)低强度机制砂混凝土和易性影响因素分析结合低强度机制砂混凝土和易性要求,初步分析出混凝土和易性影响因素,为之后的配合比设计和实验分析提供理论依据。 (2)低强度高性能机制砂混凝土配合比的设计与优化根据机制砂混凝土的和易性、力学性能与耐久性能特点,结合对低强度高性能机制砂混凝土和易性能的认识,在参考大量文献的基础上,总结现有高性能混凝土配合比设计方法,对低强度高性能机制砂混凝土配合比进行设计与优化。在《普通混凝土配合比设计规程》(JGJ55-2011)和高性能混凝土全计算法配合比设计的基础上,李固华教授提出了一种新的配合比设计方法——粉体当量体积法。这种方法是通过确定各种粉体单位体积用水量,与水泥单位体积用水量之比,来确定粉体的当量系数,在计算粉体当量总体积过程中,粉体体积要乘以当量系数。在上述配合比方法设计的基础上,实验并分析了水胶比、粉体当量总体积、用水量、砂率等不同因素,对低强度高性能机制砂混凝土和易性的影响,并确定了水胶比为0.6时,用水量为170L,粉体当量总体积为170L,砂率为45%时,混凝土拌合物的和易性最佳。 (3)矿物掺合料和外加剂对低强度机制砂混凝土和易性的影响在以上配合比方法的基础上,在混凝土中添加了矿粉、羟丙基甲基纤维素醚、膨润土、聚丙烯纤维、偏高岭土等,并对混凝土拌合物和易性、成型试块的抗压强度进行测试,对以上配合比方法基础上的结论进行实验验证和理论分析。并在保证混凝土和易性良好、抗压强度满足的条件下,确定外加剂的最佳掺量。
[Abstract]:The machine-made sand is made by mechanical crushing and sieving, and its diameter is less than 4.75mm. Different from the river sand, the machine-made sand has the characteristics of coarse grain, many angles and poor gradation. When used in medium and low strength grade concrete, the water consumption is relatively high, the mixing property of concrete is poor, and it is easy to bleed and separate. The technical indexes of machine-made sand are different from each other because of different production technology. Therefore, in order to obtain the concrete with good performance and easy construction, it puts forward higher requirements on the mix ratio. Therefore, exploring which characteristics of the machine-made sand has a great influence on the concrete and its easiness. And how to adjust the mix ratio of concrete for different characteristics of the machine-made sand makes it easy to use. This is of great practical significance to engineering application. The main purpose of this paper is to study how to prepare low strength and high performance machined sand concrete with good and easiness. The main contents of this paper are as follows: Analysis of influencing factors of low strength machined Sand concrete and its ease Combined with the requirements of low strength machine-made sand concrete and its easiness, the influence factors of concrete and easiness are preliminarily analyzed, which provides the theoretical basis for the later mix ratio design and experimental analysis. Design and Optimization of mix ratio of low strength and High performance Sand concrete According to the characteristics of mechanical properties, mechanical properties and durability of machine-made sand concrete, combined with the understanding of low-strength and high-performance machine-made sand concrete and easy performance, based on a large number of references. This paper summarizes the existing design methods of high performance concrete mix ratio, and designs and optimizes the mix ratio of low strength and high performance mechanism sand concrete. On the basis of JGJ55-2011) and the design of mix ratio of high performance concrete. Professor Li Guhua has put forward a new mix ratio design method-powder equivalent volume method. This method is based on determining the ratio of water consumption per unit volume of various powders to the water consumption per unit volume of cement. In the process of calculating the total equivalent volume of powder, the volume of powder should be multiplied by the equivalent coefficient. On the basis of the design of the above mix ratio, the effects of different factors, such as water-binder ratio, total equivalent volume of powder, water consumption and sand ratio, on the low strength and high performance machine-made sand concrete and its easiness were tested and analyzed. When the water / binder ratio is 0.6, the water consumption is 170 L, the equivalent volume of powder is 170 L, and the sand ratio is 45%, the mixing property of concrete is the best. Effect of mineral admixture and admixture on low strength machined sand concrete and its easyness On the basis of the above mixing method, mineral powder, hydroxypropyl methyl cellulose ether, bentonite, polypropylene fiber, metakaolin were added to the concrete, and the concrete was mixed and easy. The compressive strength of the molding test block is tested, and the conclusion based on the above mix ratio method is verified and analyzed theoretically, and under the condition that the concrete is easy to work and the compressive strength is satisfied. Determine the optimum amount of admixture.
【学位授予单位】：西南交通大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528

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