Production of Portland cement requires a large volume of natural raw materials and releases huge amounts of CO 2 to the atmosphere. Lower environmental impact alternatives focus on alkali-activated cements. In this paper, fluid catalytic cracking residue (FCC) was used to partially replace (0 wt %-50 wt %) ceramic sanitaryware (CSW) in alkali-activated systems. Samples were activated with NaOH and sodium silicate solutions and were cured at 65 • C for 7 days and at 20 • C for 28 and 90 days. In order to increase CSW/FCC binders' sustainability, the influence of reducing the silica concentration (from 7.28 mol•kg −1 up to 2.91 mol•kg −1) was analyzed. The microstructure of the developed binders was investigated in pastes by X-ray diffraction, thermo tests and field emission scanning electron microscopy analyses. Compressive strength evolution was assessed in mortars. The results showed a synergetic effect of the CSW/FCC combinations so that, under the studied conditions, mechanical properties significantly improved when combining both waste materials (up to 70 MPa were achieved in the mortars containing 50 wt % FCC cured at room temperature for 90 days). Addition of FCC allowed CSW to be activated at room temperature, which significantly broadens the field of applications of alkali-activated CSW binders.

The properties of a binder developed by the alkali-activation of a single waste material can improve when it is blended with different industrial by-products. This research aimed to investigate the influence of blast furnace slag (BFS) and fly ash (FA) (0-50 wt %) on the microstructure and compressive strength of alkali-activated ceramic sanitaryware (CSW). 4 wt % Ca(OH) 2 was added to the CSW/FA blended samples and, given the high calcium content of BFS, the influence of BFS was analyzed with and without adding Ca(OH) 2 . Mortars were used to assess the compressive strength of the blended cements, and their microstructure was investigated in pastes by X-ray diffraction, thermogravimetry, and field emission scanning electron microscopy. All the samples were cured at 20 • C for 28 and 90 days and at 65 • C for 7 days. The results show that the partial replacement of CSW with BFS or FA allowed CSW to be activated at 20 • C. The CSW/BFS systems exhibited better mechanical properties than the CSW/FA blended mortars, so that maximum strength values of 54.3 MPa and 29.4 MPa were obtained in the samples prepared with 50 wt % BFS and FA, respectively, cured at 20 • C for 90 days. fuel gases in coal thermoelectric plants [5] and, according to [6,7], it is estimated that approximately 750-780 million tons are produced yearly. Granulated BFS is formed by rapidly cooling melted slag during iron production [8]. As reported by the World Steel Association [9], 1629.6 million tons of steel were produced worldwide in 2016, of which 74.3% are made in blast furnaces and the remaining 25.7% in electric furnaces. Consequently, approximately 300-360 million tons of iron slag were produced globally in blast furnaces in 2016, and 160-240 million tons of steel slag were generated in electric arc and basic oxygen furnaces [10].In the last few decades, the use of different silico aluminate waste materials as a precursor in alkali-activated binders has been widely investigated [11,12]. Reusing waste materials as a precursor positively contributes to sustainable development because it limits the mining of natural resources, reduces the visual impact caused by accumulated waste, and diminishes the emissions associated with Portland cement manufacture [13,14]. Ceramic materials are a very interesting option to be explored to develop alkali-activated cements as they are chemically inert and present a long biodegradation period (up to 4000 years) [15]. Among them, ceramic sanitaryware waste (CSW) units are expected to present quite a homogeneous chemical and mineralogical composition since they are generally sintered within a narrow range of calcination temperatures (1200-1280 • C [16]). Moreover, CSW units (i.e., washbasins, lavatories, or bidets) can be easily separated from construction and demolition waste (CDW), which implies that they will present fewer impurities, such as gypsum or Portland cement. As reported by Baraldi [17], nearly 349.3 million CSW units were globally produced in 2014, of which almost 12% (41.6 million) was manufacture...

Alkali-activated cements are widely studied as alternative and sustainable binder in soil stabilization. In this research work, a mold was designed and constructed, which allowed small cubic specimens to be made (40 × 40 × 40 mm 3). With the newly designed mold, cubic samples of soil stabilized with portland cement (OPC) and alternative AAC (based on spent fluid catalytic cracking catalyst FCC) were prepared from which compressive strength was obtained. Cylindrical specimens were also prepared using the same binders as in the previous case to obtain their compressive strength. The results obtained in both cases were compared. Greater resistances for cubic samples were achieved. The cubic specimens were selected for being better in terms of standard deviation of compressive strength for AAC stabilized soil. The obtained compressive strength and standard deviation results were compared between the soil specimens stabilized with different stabilizers cured at 7, 14, 28, and 90 days. The method allows small-sized cubic specimens to be prepared. It improves ergonomics. It also facilitates a large number of specimens being obtained with a small amount of sample. Soil stabilized with AAC yielded higher compressive strength after 90 days compared to that with OPC.