Design and properties of 100% waste-based ternary alkali-activated mortars: Blast furnace slag, olive-stone biomass ash and rice husk ash

Abstract

Alkali-activated cements (AACs) technology is being widely investigated as a replacement for ordinary Portland cement (OPC) for environmental benefits. Blast furnace slag (BFS) is one of the most well known precursors used in AACs, having comparable properties to those of traditional OPC-based materials. AACs require alkali solutions, which are commonly based on a combination of sodium or potassium hydroxides with sodium or potassium silicates in high concentration. These alkali solutions represent the use of chemical reagents, and thus can have major environmental, health and economic impacts. Olive-stone (also known as olive pits) biomass ash (OBA) is a residue mainly composed of calcium and potassium oxides. Rice husk ash (RHA) is a rich silica residue from the combustion of rice husk. The combination of both residues can produce a good activating reagent for BFS-based AACs. In the present work, 100% waste-based ternary alkali-activated mortars (TAAM) based on BFS activated by OBA and RHA were developed. The mortars were assessed in terms of their dosage, curing treatment and time evolution. Finally an ecofriendly 100% waste-based TAAM with 67.39 ± 0.44 MPa after 90 days of curing at 20ºC is obtained and a complete microstructural characterization shows a dense and compact matrix with binding gel products labelled as C(K)-S(A)-H and C(K)-S-H.

Alkali-Activated Stainless Steel Slag as a Cementitious Material in the Manufacture of Self-Compacting Concrete

“…Among the main waste considered to be a source of silica are ashes from agro-industrial waste, e.g., rice husk ashes, sugar cane straw ashes, or biomass ashes. All these ashes have been studied by different researchers, and it has been observed that they contain important chemical elements from the point of view of cementing materials such as silicon, aluminium, and sodium/potassium [ 15 , 16 , 17 , 18 , 19 , 20 ].…”

Incorporation of Alkali-Activated Municipal Solid Waste Incinerator Bottom Ash in Mortar and Concrete: A Critical Review

“…Alkali-activated mortar and concrete materials have shown a commendable mechanical performance and thus such production techniques have been considered as alternative processes for the production of construction materials despite the yet low acceptance by the industry. Aside fly ash (FA) and ground granulated blast furnace slag (GGBS) have been extensively studied in the production of AAM, and other potential precursors rich in amorphous Al 2 O 3 and SiO 2 include: Agricultural wastes and aquaculture farming ashes : rise husk ash [ 1 , 2 ], palm oil fuel ash [ 3 , 4 , 5 , 6 ], corn cob ash [ 7 , 8 ], sugarcane bagasse ash [ 9 ], straw ash [ 7 , 10 ], forest biomass bottom ash [ 11 ], wood ashes [ 12 , 13 ], other agriculture-farming wastes (e.g., alfalfa steam ash, cotton gin ash, com stalk ash and switch grass ash [ 7 , 14 , 15 ]), and shell wastes [ 16 , 17 ]; Industrial waste ashes : FA [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ], coal bottom ash [ 28 ], industrials slags [ 3 , 20 , 29 , 30 , 31 , 32 , 33 , 34 ], silica fume [ 35 , …”

“…Industrial waste ashes : FA [ 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 ], coal bottom ash [ 28 ], industrials slags [ 3 , 20 , 29 , 30 , 31 , 32 , 33 , 34 ], silica fume [ 35 , 36 , 37 , 38 , 39 , 40 , 41 , 42 ], artificial pozzolans (calcined clays [ 34 , 43 , 44 , 45 ], ceramic residues [ 46 , 47 ], sedimentary rocks containing clay minerals and burned bauxites [ 48 , 49 , 50 ]), natural pozzolans (volcanic tuffs/zeolites [ 51 , 52 ], siliceous such as opal and diatomaceous earth [ 53 , 54 , 55 , 56 , 57 ], and volcanic glasses such as volcanic ashes [ 58 , 59 , 60 , 61 ,…”

Effect of Olive-Pine Bottom Ash on Properties of Geopolymers Based on Metakaolin

“…The alkaline activators used are strong alkaline solutions (NaOH, Na 2 CO 3 or hydrated alkali silicates). These alkaline materials can lead to a reduction in CO 2 emissions of between 55%-75% compared to the manufacture of Portland cement [8]. Geopolymers are characterized by having low hydration heats, high mechanical performance, and good durability against different aggressive agents (acidic media [9], sulfate attack [10], fire [11], etc.…”