GONG Fangyuan，WANG Shuyue，DU Zhengyang，CHENG Xuejiao
（School of Civil and Transportation， Hebei University of Technology， Tianjin 300401，China）
Abstract
Objective In order to enhance the strength and planting performance of ecological concrete， while effectively utilizing the waste rice husk ash generated from industrial power generation.
Methods In this study，the mix design was conducted in two stages using the volume method. Initially，the first mix design focused on investigating the water-binder ratio and the proportion of rice husk ash replacing silica fume as influencing factors. Different water-binder ratios （0. 20，0. 25，0. 30，0. 35） were chosen，and the substitution ratesofrice husk ash for silica fume varied from 0% to 100% （0，20%，40%，60%，80%，100%）， with a porosity of 20%and 7. 5% silica fume content. Subsequently， the second mix design was carried out using response surface methodology， considering influencing factors such as porosity， water-binder ratio， and rice husk ash substitution rate. The objective was to optimize the mix design based on mechanical properties through multifactor analysis. Additionally， the planting performance was validated using three herbaceous plants：bermuda grass， ryegrass and tall fescue.
Results and Discussion At 7 days， as the substitution rate of rice husk ash increases， the strength of ecological concrete decreases gradually under the three different water-binder ratios. This is due to the larger specific surface area of rice husk ash compared to silica fume， resulting in higher water demand that affects the early hydration process of cement. Rice husk ash， acting as a reactant for the secondary hydration reaction within the concrete， has a limited impact in the early stages. At 28 days，with the increase in rice husk ash substitution rate， both compressive and flexural strengths first increase and then decrease. In the compressive strength test， under water-binder ratios of 0. 25 and 0. 35， the compressive strength of ecological concrete gradually increases from 0 to 60% substitution rate. At a water-binder ratio of 0. 3， lower rice husk ash substitution rates （0 to 40%） lead to gradual strength enhancement of ecological concrete due to sufficient curing age allowing full hydration of the cementitious materials， resulting in additional formation of calcium silicate hydrate gel. However， under the water-binder ratio of 0. 25 and 0. 35 during the increase in rice husk ash substitution rate from 60% to 100%， and at a water-binder ratio of 0. 3 during the increase in rice husk ash substitution rate from 40% to 100%， the compressive strength of ecological concrete decreases with higher rice husk ash substitution rates. In contrast， the flexural strength at 28 days exhibits similar patterns among the three water-binder ratios： an increase in ecological concrete's flexural strength from 0 to 60% substitution rate，followed by a decrease in strength from 60% to 100% substitution rate of rice husk ash.
Conclusion In this study， rice husk ash is investigated as a potential replacementfor silica fume in the preparation of ecological concrete，which exhibits good mechanical properties and planting performance. Using the response surface analysis， the factors such as water-binder ratio， rice husk ash substitution rate and porosity significantly affect on the concrete’s strength， with the porosity exhibiting the most significant effect on the strength change.
Keywords：ecological concrete； rice husk ash； strength； plant growth performance； response surface method
Get Citation:Gong Fangyuan， Wang Shuyue， Du Zhengyang， et al. Mechanical and vegetation properties of rice husk ash ecological concrete［J］. China Powder Science and Technology，2024，30（2）：173−186.
Received：2023-10-28，Revised：2024-12-28，Online：2024-02-27。
Funding Project：国家自然科学基金项目，编号：52008154。
First Author：龚芳媛（1990—），女，博士，副教授，博士生导师，研究方向为道路工程材料及结构。E-mail：fgong1@hebut. edu. cn。
DOI：10.13732/j.issn.1008-5548.2024.02.015
CLC No：TB4； TQ324.8 Type Code：A
Serial No：1008-5548（2024）02-0173-14
