New low cost and green composite binder for construction

Official URL: https://risc01.sabanciuniv.edu/record=b2352857_ (Table of contents)

One of the most promising ways to make cement and concrete more sustainable is to blend them with the proper supplementary cementitious materials (SCM). This study evaluates several schist type materials as partial replacement for ordinary Portland cement (OPC). Materials received from several mines in ground powder form were studied by X-ray diffraction, thermogravimetry (TGA), and scanning electron microscopy (SEM). According to the TGA results, the activation procedures for the candidate SCMs were determined. This dissertation includes two main phases. For the first step that is named as calcined clay cement (C3), the virgin powders were heat treated in three different decomposition regimes (30%,50% and 80% of the total weight losses during thermal decomposition). These regimes correspond to the activation level of the potential SCMs due to the de-hydroxylation of the clayey minerals within them. Pozzolanic reactivity (pozzolanicity) of untreated as well as treated powders were estimated via electrical conductivity measurements in calcium hydroxide solution. Blended cement pastes with 30 wt% of OPC substitution with calcined overburden clayey materials have developed mechanical properties equal to pure cement (100wt% OPC) paste after 28 days of setting time. Two blended cement pastes prepared with candidate SCMs were compared to 100% OPC (C) and OPC composite paste with Meta-Kaolinite (MK) which is regarded as literature standard. For the second phase of project is named as limestone calcined clay and carbonate cement (LC4), the same scenario by considering the best activation temperature is carried out. The results represent the possibility of reactivation of any kind of clay class for the ordinary Portland cement partial substitution and obtaining the compressive strength as well as OPC