School of Civil Engineering and Architecture, Anhui University of Science and Technology, Huainan, 232001, Anhui Province, China.
Postdoctoral Station of Civil Engineering, Anhui University of Science and Technology, Huainan, 232001, Anhui Province, China.
Environ Sci Pollut Res Int. 2022 Aug;29(39):59173-59189. doi: 10.1007/s11356-022-19955-9. Epub 2022 Apr 5.
Rice husk ash concrete (RHAC) is a new type of concrete that has been rapidly gaining acceptance in recent years. In this paper, the improvement effect of rice husk ash (RHA) on the sulfate erosion performance of concrete was confirmed. The ratio of rice husk ash concrete (RHAC) was optimized and compared with ordinary concrete (OC). The performance degradation of 9%RHAC (rice husk ash at 9% by weight of cement) and OC within 135 times erosion dry-wet cycles solution with NaSO at 5% by weight of solution were studied, including the change of apparent phenomena, compressive strength, tensile strength, effective porosity, and dynamic elastic modulus. The microstructure changes of samples before and after sulfate dry-wet cycle were observed by using a scanning electron microscope (SEM). The results show that with the increase of sulfate dry-wet cycle times, the concrete specimen gradually peels off and expands in volume. The compressive strength and tensile strength increase first and then drop sharply, the effective porosity decreases first and then increases, and the relative dynamic elastic modulus increases and then decreases. The reason is that the ettringite and gypsum are formed by the reaction of sulfate intrusion and hydration products under wetting treatment. After drying treatment, ettringite and free water combine to form sodium sulfate. In the early of circulation, ettringite, gypsum, and sodium sulfate fill the internal pores of the concrete and improve the density. As the number of sulfate dry-wet cycles increases, expansion products accumulate, causing structural expansion damage and deterioration of mechanical performance. However, the hydrated calcium silicate hydrate gel was produced by mixing rice husk ash with concrete to improve the material strength and corrosion resistance. The deterioration degree of the 9%RHAC is better than that of OC at all stages. Finally, the damage constitutive models were established, and the accuracy is higher compared with the measured value.
稻壳灰混凝土（RHAC）是近年来迅速得到认可的一种新型混凝土。本文证实了稻壳灰（RHA）对混凝土硫酸盐侵蚀性能的改善效果。优化了稻壳灰混凝土（RHAC）的比例，并与普通混凝土（OC）进行了比较。研究了 9%RHAC（稻壳灰占水泥重量的 9%）和 OC 在 5%重量溶液硫酸钠侵蚀干湿循环 135 次过程中的性能退化，包括表观现象、抗压强度、抗拉强度、有效孔隙率和动态弹性模量的变化。利用扫描电子显微镜（SEM）观察了硫酸盐干湿循环前后样品的微观结构变化。结果表明，随着硫酸盐干湿循环次数的增加，混凝土试件逐渐剥落并膨胀。抗压强度和抗拉强度先升高后急剧下降，有效孔隙率先降低后升高，相对动态弹性模量先升高后降低。原因是在湿处理下，硫酸盐侵入和水化产物发生反应形成钙矾石和石膏。在干燥处理后，钙矾石和游离水结合形成硫酸钠。在循环早期，钙矾石、石膏和硫酸钠填充混凝土内部孔隙，提高密度。随着硫酸盐干湿循环次数的增加，膨胀产物积累，导致结构膨胀损伤和力学性能恶化。然而，稻壳灰与混凝土混合生成水化硅酸钙凝胶，提高了材料强度和耐腐蚀性。在所有阶段，9%RHAC 的劣化程度均优于 OC。最后，建立了损伤本构模型，与实测值相比，精度更高。
