Page 137 - New Trends in Green Construction

ECO-CEMENT CLINKER DESIGN VALORIZING WASTES FROM DIFFERENT INDUSTRIES
Sergio Martínez-Martínez, Luis Pérez-Villarejo, Pedro Javier Sánchez-Soto, Dolores Eliche-Quesada
Keywords: Eco-cement, Belite cement, Chamotte, Marble wastes, Aluminum industry 1. Introduction
Cement is one of the main building materials in the world, among other reasons for its durability and compatibility with other elements that allow us to make composite materials with better properties. In this research, a new type of eco-cement was investigated, valorizing industrial wastes. The principal innovation is that the typical raw materials for cement production (clay and limestone) have been replaced by industrial wastes from different production processes.
The development of this new type of cement is based on the inversion of the Alite-Belite ratio, with a proportion of Alite (C3S) at 9 wt% and Belite (C2S) at 65wt%, as main components. Belite type cement reduces the CO2 emissions by lower energy consumption, due to its lower clinkering temperature (1350-1400oC), in conjunction with a reduced content of limestone, compared to OPC. The energy demand is estimated at 15-20% less, for a LSF of 80-85% (Iacobescu et al., 2011; Uchikawa, (1994); Lawrence, (2003), Sharp et al., (1999)).
All these characteristics allow the belite-type cement to be framed within the circular economy concept. An effective use of natural resources it is intended, by manufacturing a new sustainable product through wastes from other industries that are currently disposed of in landfills.
2. Material and methods
The materials used in this study are chamotte residue (ceramic powder coming from ceramic fragments of defective pieces (bricks, tiles, etc.), manufactured at 950oC), sludge from cutting blocks and polished marble tables process and PAVAL (residue of aluminium oxide from the production of secondary aluminium, which is mainly composed of Al2O3).
The techniques used for the study of industrial wastes and the design of the belite-type cement were the following ones: X-ray Powder Diffraction (XRD), X-ray Fluorescence (XRF), Thermal Analysis (DSC/TG/DTG), Modified Bogue Equation and Quality Indices (LSF, AM, SM), Free lime content, Optical Microscopy and Scanning Electron Microscopy (SEM-EDX).
The design of the raw materials was based on the predictions of Bogue equations. A modified Microsoft’s Excel® spreadsheet was built for the estimation of the mineralogical phases, formed according to Bogue equations, and the limits imposed by the indices, as lime saturation factor (LSF), silica modulus (SM) and aluminium modulus (AM) (Iacobescu et al, 2011).
3. Results and conclusions
According to the XRF analysis results of the chamotte, a high SiO2 content is identified, as well as important CaO and Al2O3 contents. In the sludge from cutting blocks and polished marble tables
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