School of Civil Engineering, Central South University, Changsha 410075, China.
Molecules. 2021 Jan 27;26(3):647. doi: 10.3390/molecules26030647.
To improve the environmental efficiency of the reverse filling system, three strategies aim to optimize the packing density, and the mechanical property were adopted in this study. Based on the compressive packing model (CPM), the relationship between the D50 ratio and maximum theoretical packing density for a reverse filling system with 25% and 30% superfine Portland cement was established. For comparison, silica fume and steel fiber were also added to the reverse filling system, respectively. The improvement of packing density by adjusting the D50 ratio was verified through the minimum water demand method, CPM, and modified Andreasen and Andersen (MAA) model. Compared to the reverse filling system added with 3 wt % silica fume, which possesses a comparable mechanical property with the optimized group (adjusted D50 ratio), the incorporation of steel fiber shows a more significant increase. The environmental efficiency of all the samples was quantified into five aspects through the calculation based on the mix proportion, compressive strength, and hydration degree. The comprehensive evaluation demonstrated that the optimized reverse filling system exerts a lower environmental impact and possesses a much higher cement use efficiency compared to the majority of ultra-high performance concrete (UHPC)/ ultra-high performance fiber-reinforced concrete (UHPFRC) reported in published papers.
为了提高反向填充系统的环境效率，本研究采用了三种策略来优化包装密度和机械性能。基于压缩包装模型（CPM），建立了反向填充系统中 D50 比与最大理论包装密度之间的关系，其中水泥掺量为 25%和 30%的超细波特兰水泥。为了进行比较，还分别向反向填充系统中添加了硅灰和钢纤维。通过最小需水量法、CPM 和改进的 Andreasen 和 Andersen（MAA）模型验证了通过调整 D50 比来提高包装密度的效果。与添加 3wt%硅灰的反向填充系统相比，具有可比机械性能的优化组（调整后的 D50 比），钢纤维的掺入显示出更显著的提高。通过基于配合比、抗压强度和水化程度的计算，对所有样品的环境效率进行了五个方面的量化。综合评价表明，与已发表文献中报道的大多数超高性能混凝土（UHPC）/超高韧性纤维增强混凝土（UHPFRC）相比，优化后的反向填充系统具有更低的环境影响和更高的水泥利用率。
