الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
The cement industry is causing a highly negative impact due to the high consumption of raw materials and energy resources. Additionally, the manufacturing of cement emits a large amount of CO2, affecting the increase in global warming. Geopolymer concrete is a promising concrete material to become an alternative green material to ordinary Portland cement (OPC). One of the main challenges facing the Geopolymer industry is the high alkalinity makes it difficult in handling and lowering the workability of the knows admixtures. The cement industry is causing a highly negative impact due to the high consumption of raw materials and energy resources. Additionally, the manufacturing of cement emits a large amount of CO2, affecting the increase in global warming. Geopolymer concrete is a promising concrete material to become an alternative green material to ordinary Portland cement (OPC). One of the main challenges facing the Geopolymer industry is the high alkalinity makes it difficult in handling and lowering the workability of the knows admixtures. The current study aims to construct a synthetic polymer (or family of SPs) with superior plasticizing properties in a highly alkaline medium. An invented laboratory-prepared superplasticizer (SP), namely phenol-formaldehyde sulfonilate (PFS), was synthesized and its performance was measured against two types of commercial superplasticizers (naphthalene-based “Nb” and polycarboxylate-based “PCb”). The fundamental issue with SPs in alkali activated material (AAM) is that they hydrolyze when exposed to the alkaline activator (NaOH) employed in the geopolymerization operations. Therefore, the thermo-chemical treatment procedure was used to reduce the high activator alkalinity. The one-part OP-AAM was made from thermo-chemical treatment powder obtained by sintering blast furnace slag (BFS) at 300 and 500°C with 10 wt.% NaOH.
The FTIR and Gel Permeation chromatography (GPC) tests were performed to verify the admixture’s stability in a highly alkaline medium. The interaction between different SPs and Alkali activated slag (AAS) surface was investigated via zeta potential and adsorption measurements. The flowability, setting time, and compressive strength developments were evaluated for AAS mixes. The hydration products’ morphologies and phase compositions were studied using SEM and XRD.
The results reveal that the prepared PFS SP has a high stability against the highly alkaline medium. The dispersing efficiency of PFS SP resulted from the highly negative zeta potential value (-49.8 mV) compared with Nb (-41.5 mV) and PCb (-15.8 mV), also due to its high adsorption percentage as PFS, Nb and PCb adsorbed by 18.5, 9.2, 3.7% respectively. The results demonstrated a significant improvement in the workability and mechanical properties of the admixed OP-AAM made from treated powder at 500°C. The PFS SP enhanced the physico-mechanical properties of AAS as it combined several advantages at the same time compared to commercial superplasticizers; for instance, AAS pastes admixed with PFS SP have superior workability, acceptable setting time and high early strength.