Use of Fly Ash (FA) and Lime Stone Powder (LSP) In Self Compacting Cementitious Systems (SCCS) Using Ordinary Portland cement (OPC) And Its Blend with Calcium Aluminate Cement (CAC)

Abstract

Self-Compacting Cementitious Systems (SCCS) based on Ordinary Portland cement (OPC), Calcium Aluminate Cement (CAC) and Supplementary Cementitious Materials (SCMs) are very limited to field applications because no data exist on it. Such ternary binder systems have different phase compositions and microstructural characteristics than those of the hydration products based purely on OPC. In this report an experimental investigation on the blend of CAC, ISTRA-40 and Ordinary Portland cement (42.5 R) is made. Keeping Ordinary Portland cement as the main content of the blend, effects of Class-F Fly Ash (Opole) and Limestone Powder (Medenbach) as a partial replacement of blend have also been documented. In each of the ternary systems, replacement of CAC and each of the Secondary Raw Materials (SRMs) was done up to 10% in self-compacting paste and self-compacting mortar systems. Research parameters included Granulometry, flow tests, strength measurements and early volume stability. Also, along with calorimetric experiments, microstructural investigations including Scanning Electron Microscopy (SEM) with EDAX, Mercury Intrusion Porosimetry (MIP) and X-Ray Diffraction (XRD) were done. Results showed quite encouraged characteristics of cement blends with fly ash and limestone powder in comparison to OPC. Blends of CAC and OPC with each of the SRMs caused fast setting and rapid hardening thus demanded high water contents and superplasticizers doses. Due to physical effects, fly ash resulted in better flowability, dense packing, less porosity and enhanced strength at 28days of age. It was also found that at an age of 28days, cement blends with 5 and 10% CAC almost gave same strength results as of cement blends with 5 and 10% limestone powder in replacement mode. Formulations with fly ash showed less early volume changes as compared to those with limestone powder. In binary blend with 10% CAC, incorporation of 10% fly ash resulted in enhanced dormant period, slow growth of hydration products and slow rate of gain of initial strength but 28days strength was approximately twice the strength of neat cement with the same age.