Calcined clay in highly substitued pozzolanic cements

The research is about the use of calcined kaolinitic clay in highly substituted pozzolanic cements. It also compares the reactivity of calcined kaolinitic clay with fly ash and the effect of the reactivity on binders with equal clinker substitution levels. The study also investigated the chemical and physical properties of a local kaolinitic clay deposit, evaluated its pozzolanic reactivity after calcination, and compared its performance as an SCM to that of commercially used fly ash, with the aim of establishing whether thermally activated South African kaolinitic clay can serve as an effective replacement for clinker at equivalent substitution levels. The clay was thermally treated at various temperatures, and the influence of calcination conditions on reactivity was determined. The Frattini test verified that portlandite consumption was indicative of enhanced pozzolanic performance.

本研究围绕煅烧高岭质黏土（calcined kaolinitic clay）在高掺量火山灰水泥中的应用展开。研究对比了煅烧高岭质黏土与粉煤灰（fly ash）的反应活性，并考察了在相同熟料替代率下，该反应活性对胶凝材料的影响。此外，本研究对一处本地高岭质黏土矿床的化学与物理性能进行了表征，评估其经煅烧后的火山灰反应活性，将其作为辅助胶凝材料（Supplementary Cementitious Materials，简称SCM）的性能与商用粉煤灰进行对比，旨在探明热活化南非高岭质黏土能否在同等替代率下作为熟料的有效替代材料。实验团队在不同温度下对该黏土实施热处理，明确了煅烧条件对反应活性的影响规律。弗拉蒂尼试验（Frattini test）证实，氢氧化钙（portlandite）消耗量可作为火山灰性能提升的有效表征指标。