Study On Preparation And Properties Of Copper Tailings Autoclaved Aerated Concrete

Copper tailings belong to silicate solid waste,and the content of Si O₂ can reach more than 40%.At present,the main disposal method is to pile up to form tailings dam,which will not only occupy precious cultivated land,but also cause serious pollution to the surrounding soil and groundwater.Therefore,the resource utilization of copper tailings is imminent.As a new type of wall material with light weight,porous and good thermal insulation effect,autoclaved aerated concrete（AAC）is widely used in the interior and exterior wall masonry of buildings.Using copper tailings to prepare autoclaved aerated concrete can not only realize its resource utilization,but also broaden the source of siliceous raw materials for autoclaved aerated concrete.In this paper,copper tailings are used as the main siliceous material to replace part of river sand to prepare autoclaved aerated concrete.The effects of mix ratio and preparation process parameters on the physical and mechanical properties of copper tailings autoclaved aerated concrete are studied,and the optimized mix ratio and process parameters are obtained.On this basis,the effects of activator type,dosage and fumed silica content on the physical and mechanical properties of copper tailings autoclaved aerated concrete were studied,and the method of improving the performance of copper tailings autoclaved aerated concrete was obtained.Finally,the effects of copper tailings content,activator content and fumed silica content on the hydration products of copper tailings autoclaved aerated concrete were analyzed by means of SEM,XRD and FT-IR,and the hydration mechanism of copper tailings autoclaved aerated concrete was revealed.The main conclusions of this paper were as follows:（1）The effects of activator type and content on the porosity,bulk density,compressive strength,dry-wet cycle performance,drying shrinkage performance and thermal insulation performance of copper tailings autoclaved aerated concrete were studied.The analysis showed that when the activator type was sodium silicate and the content was 1.0 wt.%,the physical properties of copper tailings autoclaved aerated concrete were optimal.The effects of the content of fumed silica on the porosity,bulk density,compressive strength,dry-wet cycle performance,drying shrinkage performance and thermal insulation performance of copper tailings autoclaved aerated concrete were studied.The analysis showed that when the content of sodium silicate was 1.0 wt.%and the content of fumed silica was 8 wt.%,the physical and mechanical properties of copper tailings autoclaved aerated concrete were improved.（2）The effects of the type and content of activator on the porosity,bulk density,compressive strength,dry-wet cycle performance,drying shrinkage performance and thermal insulation performance of copper tailings autoclaved aerated concrete were studied.The analysis showed that when the type of activator was sodium silicate and the content was 1.0 wt.%,the physical properties of copper tailings autoclaved aerated concrete were optimal.The effects of the content of fumed silica on the porosity,bulk density,compressive strength,dry-wet cycle performance,drying shrinkage performance and thermal insulation performance of copper tailings autoclaved aerated concrete were studied.The analysis showed that when the content of sodium silicate was 1.0 wt.%and the content of fumed silica was 8 wt.%,the physical and mechanical properties of copper tailings autoclaved aerated concrete were improved.（3）The microstructure analysis showed that the main hydration products of copper tailings autoclaved aerated concrete were C-S-H and tobermorite.When the content of sodium silicate was 1.0 wt.%and the content of fumed silica was 8 wt.%,the number of hydration products in autoclaved aerated concrete of copper tailings was large,and the content of well-crystallized tobermorite was high.Figure[27]Table[25]Reference[72]...