Ca/Si比对赤泥-固硫灰基免烧砖性能的影响研究

Effect of Ca/Si ratio on the properties of red mud CFB fly ash-based non-fired bricks

针对赤泥、固硫灰成分复杂、产量大等限制其难以有效利用的关键问题,提出以赤泥、固硫灰等固体废弃物为主要原料制备赤泥-固硫灰基免烧砖的技术研究。通过改变赤泥和固硫灰用量调节免烧砖的Ca/Si比,对其力学性能、耐久性能和微观结构进行分析。结果表明,随着Ca/Si比的增加,免烧砖的强度呈现先增加后减小的趋势,当Ca/Si比为1.2时,免烧砖强度最高值26.63 MPa,达到MU25标准,具有较好的力学性能;经过耐水测试和抗冻测试后强度损失较小,具有较好耐久性;免烧砖的水化产物为C-S-H凝胶、C-A-S-H凝胶和钙矾石,对强度的发展起积极的促进作用,促进了力学性能和耐久性能的提升。该研究为赤泥、固硫灰等固废的综合利用提供了新的思路。

In response to the key problem that red mud and CFB fly ash have complex compositions and large production volumes that limit their effective utilization,this study proposes technical research on the preparation of red mud CFB fly ash-based non-fired bricks using solid waste such as red mud and CFB fly ash as the main raw materials.By changing the amount of red mud and CFB fly ash to adjust the Ca/Si ratio of non-fired bricks,the mechanical properties,durability,and microstructure of the non-fired bricks with different Ca/Si ratios were analyzed.The results show that with the increase of the Ca/Si ratio,the strength of unburned bricks shows a trend of first increasing and then decreasing.When the Ca/Si ratio is 1.2,the maximum strength of non-fired bricks is 26.63 MPa,which reaches the standard of MU25 and has good mechanical properties.After the water resistance test and frost resistance test,the non-fired bricks have less strength loss and better durability.The hydration products of non-fired bricks are C-S-H gel,C-A-S-H gel,and ettringite,which positively contribute to the development of strength and promote mechanical properties and durability.This research provides novel ideas for the comprehensive utilization of solid waste such as red mud and CFB fly ash.