煅烧纳米凹凸棒土对再生混凝土性能的影响

为促进废弃混凝土的资源再生利用，采用煅烧纳米凹凸棒土（NAT）改善再生混凝土性能。研究了再生骨料取代率和煅烧NAT掺量对再生混凝土工作性能、抗压强度及抗氯离子侵蚀性能的影响。并结合X-射线衍射分析煅烧NAT的物相变化，扫描电镜和孔径分析仪分析再生混凝土的微观结构。试验结果表明：煅烧可以提高NAT火山灰效应；再生混凝土各龄期抗压性能和抗氯离子侵蚀性能均随再生骨料取代率的增加而降低；未掺煅烧NAT时，再生混凝土中有较多孔隙和裂缝；当掺入适量煅烧NAT后，混凝土内孔隙和裂缝减少，界面过渡区更加密实。就工作性能、抗压强度、抗氯离子侵蚀性能和微观结构而言，当再生骨料取代率为30%时，煅烧NAT的最佳掺量为6%。

Effect of calcined Nano Attapulgite on Properties of Recycled Aggregate Concrete

To promote the regeneration of waste concrete resources, calcined Nanometer attapulgite (NAT) was used to improve the properties of recycled concrete. The effects of recycled aggregate replacement ratio and calcined NAT content on the workability, compressive strength, and resistance to chloride ion penetration of recycled concrete were investigated and combined with X-ray diffraction to analyze the phase transition of calcined NAT, scanning electron microscope and pore size analyzer to analyze the microstructure of recycled concrete. The test results show that calcination can improve the NAT volcanic ash effect. The increased recycled aggregate substitution rate decreased the compressive properties and resistance to chloride ion penetration of recycled concrete at all ages. When calcined NAT was not incorporated, there were more pores and cracks in the recycled concrete; when the appropriate amount of calcined NAT was incorporated, the pores and cracks in the concrete were reduced, and the interface transition zone was more compacted. Regarding workability, compressive strength, resistance to chloride ion attack, and microstructure, the optimum amount of calcined NAT was 6% when the recycled aggregate substitution rate was 30%.