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They concluded that the mortar with RHA presented a 50% reduction compared to the mortar prepared with Na 2SiO 3. studied the reducing CO 2 emissions in mortars with FCC and RHA as silica sources.
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introduced RHA into NaOH solution, and the mixture was ball-milled in a porcelain jar for 40 min. carried out a treatment of RHA with NaOH lasting 30 min at 90 ☌ with a magnetic stirrer. The use of RHA as a silica source has been explored in different publications with diverse treatments to obtain the activator, and combining them with various precursors. In the last decade, researchers have investigated the use of waste to totally or partially replace commercial reagents in manufacturing geopolymers or alkali-activated cements. Additionally, the reactivity and the nature of the reaction products in alkali activated materials depends on the chemical composition of the precursor and activator, and the reaction extent. stated, that a critical point for employing this type of materials is the availability of these materials in specific locations. With alkali-activated cements and geopolymers, precursor materials in most cases are by-products or waste from other industries. reviewed the recent progress in low-carbon binder by writing about the principal groups of low-carbon binders: alkali-activated cements and geopolymers, carbonate binders, belite-ye´elimite-ferrite binders. For this reason, all alternatives that can reduce cement use are welcome to reduce gas emission levels. The cement industry is responsible for about 8% of global CO 2 emissions, of which 5% are caused by the carbonate decomposition process. CO 2 is one of the greenhouse gases responsible for the climate change. Global carbon dioxide (CO 2) emissions have grown around 50% since 1990, and emissions have grown even more quickly between 20 than in the three previous decades. Goal 13 indicates the need to take urgent action to combat climate change and its impacts. The United Nations proposed 17 goals to transform the world. Sustainable Development Goals (SDGs) call to work towards prosperity while protecting the planet. The results were satisfactory, and demonstrated that employing these alternative activators from waste produces alkali activated materials with good mechanical properties, which were sometimes similar or even better than those obtained with commercial reagents.
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The corresponding pastes were characterized by X-ray diffraction, thermogravimetric analysis, and microscopy studies. Mechanical behavior was studied by the compressive strength development of mortars. RHA and DB were herein used as an alternative silica source to prepare the alkaline activating solution. FCC and CSW were employed as precursor materials, and mixtures of both showed good properties of the obtained alkali activated materials generated with commercial products as activators (NaOH/waterglass). Four waste types were employed: fluid catalytic cracking residue (FCC) from the petrochemical industry ceramic sanitary ware (CSW) from the construction industry rice husk ash (RHA) diatomaceous waste from beer filtration (DB) (food industry). This research work proposes using new waste generated in different types of industries. These types of materials are based on waste resources involving a lower carbon footprint and present similar or high properties and good durability compared to that Portland cement (PC). Resource recovery from waste is one of the most important ways to implement the so-called circular economy, and the use of alkali activated materials can become an alternative for traditional PC-based materials.