生态多孔混凝土降碱技术研究

发布时间：2019-03-10 21:58

【摘要】：生态多孔混凝土(Eco Porous Concrete,简称EPC)是一种可实现植物生长、及时调节生态平衡、美化环境,实现人类与自然生态系统协调共生的新型混凝土结构材料。由于EPC的高碱性无法满足植物的生长环境,为了实现EPC与植物生长特性的化学相容性,并提出科学、有效的EPC降碱调控方法,本论文基于材料学、植物学、生态学、化学等基础理论和专业知识,借鉴吸碱、消碱、封碱和固碱一体化的EPC降碱调控方法,系统深入地探讨了 EPC降碱技术,并借助CT扫描技术探讨了 EPC孔结构形态特征。主要研究结论如下:1.研究了水泥品种、矿物掺合料种类及掺量、酸性改性材料等因素对EPC水泥净浆pH值的影响,结果表明:采用硫铝酸盐水泥和铝酸盐水泥配制的水泥净浆的pH值较普通硅酸盐水泥配制的低2～3个单位;矿物掺合料的掺入在一定程度上能降低EPC的碱度,且其pH值随矿物掺合料掺量的增加呈下降趋势,其中硅灰降碱效果最好;酸性改性材料对降低EPC的碱度非常有限。2.研究了草酸浸泡、草酸喷涂、永凝液喷涂和快速碳化等单一降碱方法对EPC强度及碱度的影响,结果表明:经草酸浸泡后的EPC强度相比标准组而言降低了 0.5～2MPa;经草酸或永凝液喷涂处理后的EPC强度降低了 1～2MPa,且草酸喷涂对EPC强度的影响大于永凝液喷涂对EPC强度的影响;相较于自然碳化,快速碳化后的EPC强度更加稳定且略有提高。经草酸浸泡后的EPCpH值可降低0.5～2个单位;采用草酸和永凝液进行表面喷涂处理后的EPC pH值均降低1～2个单位,且草酸和永凝液均是喷涂两次效果最佳,pH值基本稳定在10.3左右;经快速碳化后的EPCpH值相较于自然碳化后的pH值下降约1.7个单位。因此对EPC强度及碱度要求均较高的工程可采用单一降碱法进行降碱处理。3.内掺硅灰与硫酸亚铁,外加永凝液喷涂技术及快速碳化技术的复合降碱方法,EPC强度及碱度的研究结果表明:采用内掺10%的硅灰和4%的硫酸亚铁技术,外加快速碳化技术,最后采用永凝液喷涂封碱的复合降碱工艺,可实现EPC28d抗压强度达8.3MPa,pH值降至9.71,56d抗压强度可达8.8MPa,pH值可降至9.82的效果,可满足EPC设计强度值和植物生长所需的碱性环境要求。4.基于EPC与植被化学相容性匹配准则,筛选的五种植物中狗牙根和高羊茅类植物与EPC的匹配度较高,为EPC优选相应植物品种提供了对应法则。5.借助CT扫描技术,结合分形理论分析了 EPC断面分形维数的计算方法,建立了面分形维数与孔隙率之间的相关关系,且相关性较好,搭建了EPC孔结构分形维数与其宏、微观结构性能的相互关系。
[Abstract]:Ecological porous concrete (Eco Porous Concrete,) is a new kind of concrete structure material, which can realize plant growth, adjust ecological balance in time, beautify environment and realize harmonious symbiosis between human and natural ecosystem. In order to realize the chemical compatibility between EPC and plant growth characteristics, and to put forward a scientific and effective method to control the alkalinity of EPC, this paper is based on materials, botany, ecology, and so on, because the high alkalinity of EPC can not satisfy the growth environment of plants. Based on the basic theory and professional knowledge of chemistry, the EPC alkali reduction technology is systematically and deeply discussed by referring to the methods of alkali absorption, alkali elimination, alkali sealing and alkali fixation, and the structural and morphological characteristics of EPC pores are discussed by means of CT scanning technique. The main conclusions are as follows: 1. The effects of cement varieties, mineral admixtures and acid modified materials on pH value of EPC cement paste were studied. The results show that the pH value of the cement paste prepared by sulphoaluminate cement and aluminate cement is 3 units lower than that of ordinary Portland cement. The alkalinity of EPC can be reduced by adding mineral admixture to a certain extent, and its pH value decreases with the increase of mineral admixture content, among which silica fume is the best. Acid modified material has very limited effect on decreasing basicity of EPC. 2. The effects of oxalic acid immersion, oxalic acid spraying, permanent solidification solution spraying and rapid carbonization on the strength and alkalinity of EPC were studied. The results showed that the EPC strength of oxalic acid immersion group was lower than that of standard group. After spraying with oxalic acid or permanent solidified solution, the strength of EPC decreased by 1 ~ 2 MPA, and the effect of oxalic acid spraying on the strength of EPC was greater than that of spraying with permanent solidifying liquid on the strength of EPC. Compared with natural carbonation, the strength of EPC after rapid carbonization was more stable and slightly improved. After soaking in oxalic acid, the pH value of EPC could be reduced by 0.5% and 2 units respectively. The EPC pH value of the surface sprayed with oxalic acid and immortalized liquid was reduced by 1 / 2 units, and both oxalic acid and immortalized liquid were the best spraying time, and the pH value was basically stable at about 10.30; The pH value of EPC after rapid carbonization is about 1.7 units lower than that of natural carbonization. Therefore, for projects with high EPC strength and alkalinity requirements, a single alkali reduction method can be used for alkali reduction treatment. 3. The research results of EPC strength and alkalinity show that the technology of adding 10% silica fume and 4% ferrous sulfate, and the addition of rapid carbonization technology are used, and the results show that the technology of mixing silicon fume and ferrous sulfate, the spraying technology of permanent coagulation liquid and the rapid carbonization technology, the results of the study on the strength and alkalinity of silica fume and ferrous sulfate are as follows: Finally, the EPC28d compressive strength can reach 8.3 MPA, the pH value can be reduced to 9.71, the compressive strength can reach 8.8 MPA after 56 days, and the pH value can be reduced to 9.82 by using the compound alkali reduction technology of permanent coagulation liquid spray sealing. Can meet the EPC design strength value and basic environmental requirements for plant growth. 4. Based on the matching criterion of chemical compatibility between EPC and vegetation, the matching degree of EPC with EPC was higher among the five selected plants, which provided a corresponding rule for the selection of corresponding plant varieties by EPC. 5. With the help of CT scanning technology and fractal theory, the calculation method of fractal dimension of EPC section is analyzed, and the correlation between fractal dimension of surface and porosity is established. The fractal dimension of EPC pore structure and its macro are built, and the relationship between fractal dimension of surface fractal dimension and porosity is established. The relationship between microstructure and properties.
【学位授予单位】：中南林业科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TU528

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