Reconciling the need of producing reliable building materials, with that of drastically cutting greenhouse gas emissions represents one of the current fundamental technological and societal challenges. To this end, we assessed the performance of a binder alternative to ordinary Portland cement (OPC) based on the alkali activation of a blend of locally sampled, impure calcined clay of smectitic composition, with waste calcium carbonate from the marble industry.

The microstructure of the final product was investigated by means of scanning electron microscopy and X-ray tomography, and the phase composition by X-ray diffraction, implementing the PONKCS (partial or not known crystal structure) approach. Results of compressive strength tests show an adequate mechanical performance of these materials, with values of the compressive strength as high as 60 MPa after 20 days under room temperature curing. Replacement of a small quantity of the alkaline activator with sodium citrate induces enhanced workability and mechanical performance, reducing the amount of entrained air voids. The use of alkali activated calcined smectite clay – waste calcium carbonate blends represents a valuable complementary approach with respect to alkali activation of metakaolin and calcined kaolinite clay – OPC blends, towards the development of carbon-free binders.

大幅减少温室气体的排放量与生产可靠的建筑材料的需求相协调，是当前基本的技术和社会挑战之一。为此，我们基于对局部取样的，不纯的煅烧黏土组成的黏土与大理石工业产生的废碳酸钙的混合物进行碱活化，从而评估了替代普通波特兰水泥（OPC）的粘结剂的性能。

通过扫描电子显微镜和X射线断层扫描研究最终产品的微观结构，并通过X射线衍射研究相组成，以实现PONKCS（部分或未知的晶体结构）方法。抗压强度测试的结果表明这些材料具有足够的机械性能，在室温下固化20天后其抗压强度值高达60 MPa。用柠檬酸钠替代少量的碱性活化剂可提高可加工性和机械性能，从而减少夹带的气孔数量。在偏高岭土和煅烧高岭石粘土– OPC混合物的碱活化方面，使用碱活化的煅烧蒙脱石粘土–废碳酸钙混合物代表了一种有价值的补充方法，