Waste-Based One-Part Alkali Activated Materials

Abstract

Ordinary Portland Cement is the most widely used binder in the construction sector; however, a very high carbon footprint is associated with its production process. Consequently, more sustainable alternative construction materials are being investigated, namely, one-part alkali activated materials (AAMs). In this work, waste-based one-part AAMs binders were developed using only a blast furnace slag, as the solid precursor, and sodium metasilicate, as the solid activator. For the first time, mortars in which the commercial sand was replaced by two exhausted sands from biomass boilers (CA and CT) were developed. Firstly, the characterization of the slag and sands (aggregates) was performed. After, the AAMs fresh and hardened state properties were evaluated, being the characterization complemented by FTIR and microstructural analysis. The binder and the mortars prepared with commercial sand presented high compressive strength values after 28 days of curing-56 MPa and 79 MPa, respectively. The mortars developed with exhausted sands exhibit outstanding compressive strength values, 86 and 70 MPa for CT and CA, respectively, and the other material’s properties were not affected. Consequently, this work proved that high compressive strength waste-based one-part AAMs mortars can be produced and that it is feasible to use another waste as aggregate in the mortar’s formulations: the exhausted sands from biomass boilers.

Unravelling the Affinity of Alkali-Activated Fly Ash Cubic Foams towards Heavy Metals Sorption

“…The interest in the use of alkali-activated materials (binders produced by the alkali activation of reactive solid precursors [4]) for water and wastewater treatment is recent, despite their obvious suitability to act as adsorbents [5,6], endowed by their intrinsic nano-and micro-porosity [7], and their negatively charged framework balanced by cations that can be exchanged for other cations [8] present in wastewaters [9,10]. Other technical advantages over benchmark adsorbents (e.g., activated carbons) are the possibility of being produced at room temperature, and the use of various waste streams or by-products as precursors [11][12][13][14].…”

Valorization of Fly Ashes and Sands Wastes from Biomass Boilers in One-Part Geopolymers

“…Furthermore, the development of one-part alkali-activated materials is very recent and they can play an important role in the substitution of cement once their associated carbon footprint is lower than that of the cement. Therefore, the aim of the work is, based on a previous work [ 14 ] in which sands wastes were used to develop one-part geopolymer mortars, to study the effect of replacing BFS with biomass FA. The developed materials were characterized in terms of mechanical strength at 7 and 28 days of curing, water absorption, density, leaching and freeze–thaw resistance.…”

Special Issue: “Ceramics and Construction Materials”

“…Several published articles are focused on binders and concrete [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], so showing the great scientific interest associated to these materials. Attention has been reserved to the low-carbon cements, i.e., cementing binders produced with low greenhouse emissions [ 1 , 2 ].…”

“…Several published articles are focused on binders and concrete [ 1 , 2 , 3 , 4 , 5 , 6 , 7 ], so showing the great scientific interest associated to these materials. Attention has been reserved to the low-carbon cements, i.e., cementing binders produced with low greenhouse emissions [ 1 , 2 ]. Among these binders are fly ash belite cements and alkali activated materials, the latter representing a potential instrument for the future sustainable development of the construction industry.…”

“…In addition, the application of a kinetic model based on the Jander’s equation reveals to be appropriate for predicting the evolution of the hydrothermal process. Very interesting results were obtained by Gonçalves et al [ 2 ], which focused their research on the production and characterization of one-part alkali activated material obtained exclusively from industrial byproducts and wastes. At this purpose, granulated blast-furnace slag and exhausted sands from biomass boilers were used as components of mortars.…”