Characterization of Effloresences of Ambient and Elevated Temperature Cured Fly Ash Based Geopolymer Type Concretes

Abstract

Efflorescences formed on the surface of air (ambient) and elevated (70°C) temperatures cured high calcium fly ash based geopolymer type concretes have been characterized by the XRD, SEM-EDX and FTIR techniques. The mineralogical composition of the efflorescence depends on curing temperature. At ambient temperature the main phase of efflorescence consists of atmospheric carbonation product of sodium hydroxide such as thermonatrite (Na2(CO3)·H2O, PDF 8--448), while in the 70°C cured concrete it represents sodium calcium carbonates gaylussite (Na2Ca (CO3)2·5H2O, PDF 21-343). Mineralogical composition difference between the ambient and 70°C cured concrete’s efflolorescences is related to chemical reaction of alkaline liquid with fly ash constituents.

Inorganic polymers made of fayalite slag: On the microstructure and behavior of Fe

“…The band at~1375 cm À1 is most likely also linked with C-O carbonate stretching vibrations. In this particular case, the bands appear at lower wavenumbers than all the Na-carbonates that have been identified in other works [36][37][38] and whose FTIR spectra could be retrieved in the literature, 28 Considering the Si-O vibrations region, the width of the stretching band remains wide for the IPs but, unlike the starting slag, the shoulder at lower wavenumbers (between 800 and 600 cm À1 ) seems to have disappeared. Considering that the band from 622 to 780 cm À1 is associated with Si-O-Si bending vibrations, 32 this characteristic indicates that part of the starting slag dissolves and most likely participates in the synthesis of the IP, which is in line with microscopic observations.…”

“…The band at ~1375 cm −1 is most likely also linked with C–O carbonate stretching vibrations. In this particular case, the bands appear at lower wavenumbers than all the Na‐carbonates that have been identified in other works and whose FTIR spectra could be retrieved in the literature, that is, nahcolite (NaHCO 3 ), trona (Na 3 (HCO 3 )(CO 3 )·2H 2 O), gaylussite (Na 2 Ca(CO 3 ) 2 ·5H 2 O), and sodium carbonate (Na 2 CO 3 ).…”

Behavior of Fibers in Geopolymer Concrete: A Comprehensive Review

“…Also, the inclusion of basalt fibers in fly ash geopolymer concrete affects the fracture toughness and fracture energy [158]. Temuujin et al [159] explained that basalt fiber coating is a prime factor that influences the strength of basalt fiber-reinforced geopolymer concrete (BFRGC). Spooled fibers coated with a carbon layer illustrated the best bonding between the fibers and polymer matrix compared to the chopped fibers.…”

Use of residual waste glass in an alkali-activated binder – Structural characterization, environmental leaching behavior and comparison of reactivity

“…New bands appearing in the spectra of the treated samples have varying intensities from one sample to another. Bands at 1450 and 870 cm -1 indicate the vibration of C-O bonds, originating from carbonates [50,51]. The Na or Ca in the treated RWG can have partially reacted with CO2 in the air to produce Na-or Ca-carbonate phases.…”