Jakhrani Sadam Hussain, Ryou Jae Suk, Jeon In Kyu, Woo Byeong Hun, Kim Hong Gi
Department of Civil and Environmental Engineering, Hanyang University, Seoul 04763, Korea.
Materials (Basel). 2019 Aug 21;12(17):2654. doi: 10.3390/ma12172654.
The purpose of this study was to prevent early age autogenous shrinkage in high-strength mortars with saturated tea waste particles. In general, high strength and high performance concretes are made with low water/binder ratios; hence, they are susceptible to shrink at early ages. This shrinkage occurs due to self-desiccation that leads to autogenous shrinkage. To overcome self-desiccation problems in high-strength cement composites, it is necessary to keep the composites moist for a long time. Pre-saturated porous lightweight aggregates and super absorbent polymers are the most commonly used materials in high-strength cement composites to keep them moist for a long time; however, in this study, porous tea waste particles were used to keep the cement mortars moist. Pre-saturated tea waste particles were used in two different size proportions, making up as much as 3% of the volume of the binder. Moreover, commonly used lightweight aggregate (perlite) was also used to compare the outcomes of specimens made with tea waste particles. Different parameters were observed, such as, flow of fresh mortars, autogenous shrinkage, mechanical strengths and microstructure of specimens. The addition of tea waste and perlite particles in mortars made with Ordinary Portland cement (OPC) as the only binder, showed a reduction in flow, autogenous shrinkage and mechanical strengths, as compared to mixes made with partial addition of silica fume. Although, the use of silica fume improved the mechanical strength of specimens. Moreover, the use of saturated tea waste and perlite particles also improved the microstructure of specimens at an age of 28 days. The results revealed that the saturated tea waste particles have the ability to prevent autogenous shrinkage but they reduce strength of high-strength mortars at early ages.
本研究的目的是防止掺有饱和茶渣颗粒的高强度砂浆出现早期自收缩现象。一般来说，高强度和高性能混凝土是采用低水胶比配制而成的；因此，它们在早期容易产生收缩。这种收缩是由于自干燥导致自收缩而发生的。为了克服高强度水泥基复合材料中的自干燥问题，有必要使复合材料长时间保持湿润。预饱和多孔轻骨料和高吸水性聚合物是高强度水泥基复合材料中最常用的使材料长时间保持湿润的材料；然而，在本研究中，使用多孔茶渣颗粒来保持水泥砂浆湿润。预饱和茶渣颗粒以两种不同的尺寸比例使用，其用量占胶凝材料体积的3%。此外，还使用了常用的轻骨料（珍珠岩）来比较用茶渣颗粒制成的试件的结果。观察了不同参数，如新鲜砂浆的流动度、自收缩、力学强度和试件的微观结构。与部分添加硅灰的混合料相比，在仅以普通硅酸盐水泥（OPC）作为胶凝材料制成的砂浆中添加茶渣和珍珠岩颗粒，会使流动度、自收缩和力学强度降低。尽管如此，硅灰的使用提高了试件的力学强度。此外，使用饱和茶渣和珍珠岩颗粒也改善了28天龄期试件的微观结构。结果表明，饱和茶渣颗粒有能力防止自收缩，但会降低高强度砂浆的早期强度。
