Superplasticizer Addition to Carbon Fly Ash Geopolymers Activated at Room Temperature

Abstract

Present concerns about global warming due to the greenhouse emissions in the atmosphere have pushed the cement industry to research alternatives to ordinary Portland cement (OPC). Geopolymer binder may constitute a possible breakthrough in the development of sustainable materials: understanding the effectiveness and the influences of superplasticizers on geopolymer systems is one of the essential requirements for its large-scale implementation. This study aims to investigate the possibility of using commercially available chemical admixtures designed for OPC concrete, to improve fresh properties of fly ash-based geopolymers and mortars. A special emphasis is laid upon evaluating their influence on mechanical and microstructural characteristics of the hardened material realized under room-temperature curing conditions. Results indicate that the addition of a polycarboxylic ether-based superplasticizer, in the amount of 1.0 wt. % by mass of fly ash, promotes an improvement in workability without compromising the final strength of the hardened material. Moreover, the addition of the polycarboxylic ether- and acrylic-based superplasticizers induces a refinement in the pore structure of hardened mortar leading to a longer water saturation time.

Development of banana fibers and wood bottom ash modified cement mortars

“…For the different compositions, the bands ranging from 3437.26 to 3450.77 cm À1 is denoted for stretched OH À group with a pronounced increase in the intensity of the particular band for Y when compared with others. This is indicative of the effective chemical reactions and stability among the BF, WBA and the SBR polymer in the mixes V, W and X more than mix Y [48]. Basically, there were little variations among the bands of the four spectras considered because the amount of coincidences among them is high.…”

Binders alternative to Portland cement and waste management for sustainable construction—part 1

“…137 As workability is one of the main requirements, research on superplasticizers suitable for fly ash geopolymers needs to be emphasized. [138][139][140][141][142][143][144][145]146 Clayey sediments and sludge for geopolymers Geopolymers are attractive because natural and industrial silico-aluminates wastes may be used as precursors. The exploration for alternative low cost and easily available materials led among others to "normal clays".…”

Beneficial Use of MIBC in Metakaolin-Based Geopolymers to Improve Flowability and Compressive Strength

“…Polycarboxylates (PCEs) are comb-shaped superplasticizers and are known to dramatically reduce the water demand in cement concrete [ 9 ]. PCEs are steric admixtures, and their dispersing ability is due to steric hindrance effects rather than electrostatic repulsion [ 10 ]. Mutual repulsion of the particles is governed by the solubility of the polymeric tails in the liquid [ 10 ].…”

“…PCEs are steric admixtures, and their dispersing ability is due to steric hindrance effects rather than electrostatic repulsion [ 10 ]. Mutual repulsion of the particles is governed by the solubility of the polymeric tails in the liquid [ 10 ]. The steric hindrance is expected to affect geopolymers or alkali-activated materials.…”

“…In addition, it has not been reported whether plasticizers or superplasticizers applied in geopolymers or alkali-activated materials function as efficiently as when they are applied in cement concrete. For instance, a recent study reported that the addition of a polycarboxylic ether-based superplasticizer improved the flowability of fly ash-based geopolymers without compromising the final strength of the hardened material, which was determined based on a performance assessment of a range of natural and synthetic polymers [ 10 ]. The flowability, however, was only slightly improved, and the effect of the additional water present in the superplasticizers was not even considered.…”