基于净浆流变性的自密实混凝土配合比设计方法研究

发布时间：2019-05-28 21:45

【摘要】：堆石混凝土已越来越多地应用于水利工程中，为了满足堆石孔隙的高填充率以保证堆石混凝土工程质量，需要对其中自密实混凝土（SCC）的工作性能进行严格控制，关键在于对SCC组成材料进行合适的配合比设计。本论文的研究目的是基于SCC基本组成相——净浆的流变性预测指导SCC工作性能，从而简化SCC配合比设计过程，节省工程实验的材料、时间和人力。论文通过建立力学模型从物理本质上分析SCC中砂浆流变性对石子受力运动情况及SCC工作性能的影响，并结合净浆砂浆流变性之间的经典关系，建立了净浆流变性和SCC工作性能间的关联。通过系列SCC和相应水泥净浆的性能检测实验验证上述理论模型和关联的正确性，提出基于净浆流变性的SCC配合比设计方法。论文利用该方法成功配制出新型的纯石粉SCC，验证了该方法的实用性和可行性，配制过程充分体现了该方法的简捷有效，实现了由净浆流变性对SCC工作性能的预测指导，为SCC配合比设计提供了一种新的理念。为了更好地指导SCC配合比设计过程中相关参量的调整、材料特性的控制和改进，论文对净浆流变性的影响因素——聚羧酸减水剂、水和水泥水化从作用机理上展开了研究。通过系列石粉净浆实验并利用沉降天平法测量净浆中絮凝结构粒径分布，计算得到絮凝结构表面覆盖的水膜层厚度，这一厚度与净浆流变性之间呈现一一对应的强相关关系，能够综合体现聚羧酸减水剂和水两个因素的影响作用，且由此指标量化分析得到聚羧酸减水剂对净浆流变性的调整改善效果更为有效。通过实验分析水泥净浆流变性、聚羧酸减水剂吸附量、水泥水化产物随时间的变化情况，得到单位表面积颗粒上减水剂吸附量与净浆经时流变性有较强正相关性的结论，为从材料特性方面进行控制改进，同时实现浆体流变性及其保持能力的需求提供理论基础。上述研究提出并验证了基于净浆流变性的SCC配合比设计方法，并从机理上分析研究了净浆中聚羧酸减水剂、水和水泥水化对净浆流变性的影响作用，，为今后堆石混凝土工程中SCC的生产和工作性能调控提供简便、高效、合理的解决思路。
[Abstract]:Rockfill concrete has been more and more used in water conservancy projects. In order to meet the high filling rate of rockfill pores to ensure the quality of rockfill concrete engineering, it is necessary to strictly control the working performance of self-compacting concrete (SCC). The key is to carry on the suitable mix proportion design to the SCC composition material. The purpose of this paper is to guide the performance of SCC based on the prediction of the Rheology of SCC, which is the basic phase of slurry, so as to simplify the design process of SCC mix ratio and save the material, time and manpower of engineering experiment. In this paper, the physical essence of mortar in SCC is analyzed by establishing a mechanical model to analyze the effect of mortar Rheological properties on the force movement of stone and the working performance of SCC, and combined with the classical relationship between the Rheological properties of pure mortar. The relationship between the hemorheology of clean pulp and the working performance of SCC was established. The correctness of the above theoretical model and correlation is verified by a series of SCC and the corresponding cement paste performance test experiments, and a SCC mix proportion design method based on the Rheological properties of the paste is proposed. In this paper, a new type of pure stone powder SCC, was successfully prepared by using this method to verify the practicability and feasibility of the method. The preparation process fully reflects the simplicity and effectiveness of the method, and realizes the prediction guidance of the performance of SCC by the Rheological properties of the pure slurry. It provides a new concept for SCC mix design. In order to better guide the adjustment of related parameters and the control and improvement of material properties in the process of SCC mix design, the influencing factors of net slurry Rheological properties, such as polycarboxylic acid superplasticizer, water and cement hydration, were studied in this paper. The particle size distribution of flocculation structure in the slurry was measured by a series of stone powder pulp purification experiments and the sedimentation balance method was used to measure the particle size distribution of the flocculation structure. The thickness of the water film layer covered on the surface of the flocculation structure was calculated, and there was a strong correlation between the thickness and the Rheological properties of the slurry. It can comprehensively reflect the influence of two factors: polycarboxylic acid water reducer and water, and the quantitative analysis of this index shows that the effect of polycarboxylic acid water reducer on the adjustment and improvement of the Rheological properties of pure pulp is more effective. Through the experimental analysis of the Rheological properties of cement paste, the adsorption capacity of polycarboxylic acid water reducer and the change of cement hydration products with time, it is concluded that there is a strong positive correlation between the adsorption capacity of water reducer on particles per unit surface area and the time-dependent hemorheology of pure slurry. It provides a theoretical basis for the control and improvement of material properties and the need to realize the hemorheology and retention ability of slurry at the same time. The above research puts forward and validates the design method of SCC mixture ratio based on the Rheological properties of clean pulp, and analyzes and studies the effect of polycarboxylic acid superplasticizer, water and cement hydration on the Rheological properties of clean pulp from the mechanism point of view. It provides a simple, efficient and reasonable solution for the production and performance control of SCC in rockfill concrete engineering in the future.
【学位授予单位】：清华大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU528

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