Alkali activation of recycled ceramic aggregates from construction and demolition wastes

Abstract

Environmental concerns are becoming increasingly more significant worldwide, thus creating the urgent need for new sustainable alternatives in the industrial sector. The present study assesses the fundamental properties of ceramic residue (CR) originated by demolition operations, specifically, the floor and wall tiles and sanitaryware furniture, for further incorporation in the construction sector, namely in alkali-activated binders, mixed with other better-known precursors - fly ash (FA) and ladle furnace slag (LFS). Different CR/FA and CR/LFS weight ratios were considered and analyzed by mechanical behavior and microstructural analysis, which included uniaxial compression strength (UCS) tests, Scanning Electron Microscopy (SEM), X-ray Energy Dispersive Analyser (EDX), X-ray diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR). Results obtained showed that the combination of CR and FA or LFS, activated with sodium silicate, produced UCS values higher than 20 MPa and 59 MPa, respectively, after 90 days curing.

Study on Portland Cement Pastes Containing Sanitary Ware Ceramic Wastes at Elevated Temperatures

“…This result was improved and enhanced with firing temperatures only up to 400 ℃, but then decreased with any further rise of firing temperature › 400℃. The increase of FS is mainly due to that the firing temperatures initiated and promoted the thermal interactions between the different ingredients of the samples so that it improved and increased the modification and development of the formed CSHs, while the decrease of FS is essentially contributed to the decomposition of Ca (OH)2 or may be due to significant dehydration within the cement matrix modifying the physical properties and the dehydration of both calcium silicate hydrates (CSHs) that occurred at temperature beyond 400 °C [47][48][49][50]. This caused the weakening of pastes, which in turn resulted in the destruction of micro-structural arrangements in the hardened cement pastes.…”

“…The decrease in CS at firing temperature › 400 °C may be attributed to the significant dehydration within the cement matrix modifying the physical properties of the cement pastes. The sharp fall in CS [49] by > 400 °C onward could be due to the decomposition of Ca(OH)2 and dehydration of both calcium silicate hydrates (CSHs) that occur at temperature beyond 400 °C [18,[42][43][44][45]. This often caused the break down or at least the weakening of bonds of cement pastes.…”

“…This often caused the break down or at least the weakening of bonds of cement pastes. This always caused the destruction of the microstructural arrangements in constituents of cement pastes [49][50][51][52]. The sharp decline in CS at firing temperatures > 400 °C may be due to the decomposition of Ca(OH)2 and dehydration of both calcium silicate hydrates (CSHs) that occur at temperature beyond 400 °C [18,20].…”

“…As a result, the presence of CSPW in the cement pastes increased the resistance of the hardened cement pastes to the high temperatures up to 400 ℃. The improved resistance against high temperatures with CSPW inclusion can be mainly attributed to the decreased amount of Ca (OH)2 with its pozzolanic activity [48][49][50][51][52][53].…”

Mortero a base de aglutinantes proteínicos y residuos minerales para elementos interiores = Mortar based on protein binders and mineral waste for interior elements

“…Spain is one of the largest producers of these raw materials, in seventh place with a contribution of 3.5% worldwide. Within this industry there is more than one type of waste to consider; in the case of solid waste, such as spoiled leather waste and above all capillary fibres, which generally end up in open dumps, where biological oxidation releases nitrogenous compounds after leaching of substances during and after precipitation, causing eutrophication of water sources (Gaibor et al, 2020). Next to these leftover elements are the liquids, which start at the most elementary stage of leather processing.…”