水热合成硅酸盐材料性能提升技术研究.doc

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摘要

加气混凝土是应用最为广泛的水热合成硅酸盐材料，具有质量轻、导热系数低，市场潜力巨大，在2013年国家发改委、住房和城乡建设部制定的《绿色建材行业方案》中被列为“安全耐久、节能环保、便利的绿色建材”。但是，高吸水率和高收缩的性能缺陷，常导致加气混凝土墙体开裂。本文通过材料组成和微观结构优化，使加气混凝土性能满足自保温墙体使用要求。主要研究内容和结果如下：

基于试验研究和统计分析，揭示了加气混凝土吸水率对其干燥收缩性能的影响规律，建立了加气混凝土强度与材料组成和结构的关系。研究发现：加气混凝土干燥收缩是体积吸水率的四次方函数；吸水率小于11.0vol. %时，加气混凝土收缩较小，且吸水率为11.0vol. %~18.0 vol. %时，收缩值增量较小；吸水率大于26.1vol. %时，加气混凝土的干燥收缩值显著增加；加气混凝土最优钙硅比为0.74，降低毛细孔体积率是实现加气混凝土减缩增强的有效途径。

研究了胶结料、铝掺杂和专用减水剂对加气混凝土强度和收缩性能的影响，通过XRD和SEM等方法，分析了水热合成产物。研究发现：低温熟料和铝掺杂基料改变了水热合成产物构成，前者促进了高强度水化钙黄长石形成，后者促进了C-A-S-H的形成，从而获得低收缩、高强度加气混凝土；专用减水剂通过降低水料比和毛细孔体积率，使加气混凝土收缩降低、强度提高。

基于BSE图像分析，定量了高性能砂加气混凝土和粉煤灰加气混凝土的晶体的体积率和胶体的体积率。研究发现：在相同的水热合成工艺条件下，高性能砂加气混凝土的晶体与胶体总体积率为粉煤灰加气混凝土的1.4倍，两种加气混凝土的晶体/胶体体积比分别为1.7和1.2。

工业化应用试验表明，通过优化加气混凝土配比，降低毛细孔体积率，可显著提升加气混凝土强度和体积稳定性。

关键词：建筑材料；加气混凝土；微观结构；强度；晶胶比

 

                                                                   

Abstract

    Aerated concrete is the most used hydrothermal silicate material, has the advantages of light weight, low thermal conductivity, market potential is tremendous, in 2013 the national development and Reform Commission, the Ministry of housing 、 urban and rural construction to develop "green building materials industry plan" is listed as "safety and durability, energy saving and environmental protection, convenience of green building materials". However, the high water absorption rate and the performance of the high shrinkage defects, often lead to aerated concrete wall cracking. In this paper, the performance of aerated concrete can meet the requirements of self-insulation wall using the material composition and microstructure optimization. The main research contents and results are as follows:

    Based on the experimental study and statistical analysis, the influence of the water absorption rate of aerated concrete on drying shrinkage of the aerated concrete is revealed, and the relationship between the strength of aerated concrete and the structure of the air entrained concrete is established.It is found that the drying shrinkage of autoclaved aerated concrete is volume water absorption rate of the quartic function; the bibulous rate is less than of 11.0vol%, aerated concrete shrinkage is small, and when the water absorbing rate for 11.0vol.%~18.0 vol.% , shrinkage value incremental is smaller; water absorption rate  greater than 26.1vol.% , drying shrinkage of autoclaved aerated concrete value increased significantly; aerated concrete optimal calcium silicon ratio 0.74, reduce the volume ratio of pores is the effective way to realize the reduction of aerated concrete reinforced.

    The influence of cement, Al doping and special water reducer on the strength and shrinkage of aerated concrete was studied. The hydrothermal silicate material were analyzed by SEM and XRD.It was found that the low temperature clinker and aluminum doped base material change constitutes of hydrothermal silicate material , the former promotes the formation of high strength water gehlenite,the later promote the C-A-S-H formation, resulting in low shrinkage, high strength aerated concrete; special water reducing agent by reducing water material ratio and pore volume rate, aerated concrete shrinkage is reduced, and the strength increase.

    Based on the BSE image analysis, the volume rate of the crystal and the volume rate of the colloidal volume of high performance sand aerated concrete and fly ash aerated concrete are quantitatively analyzed. Study found that: under the same hydrothermal synthesis process conditions, high performance aerated concrete colloidal crystals with the total volume rate is 1.4 times that of the fly ash aerated concrete, two aerated concrete of crystal / colloid volume ratio, 1.7 and 1.2, respectively.

    Industrial application test showed that by optimizing the ratio of aerated concrete, reduce the volume ratio of pores, can significantly improve the strength and volume stability of aerated concrete.

Key words:Building materials; aerated concrete; microstructure; strength;shrinkage；