Hydration products, internal relative humidity and drying shrinkage of alkali activated slag mortar with expansion agents

Jia, Zijian; Yang, Yuanyuan; Yang, Lingyan; Zhang, Yamei; Sun, Zhanwen

doi:10.1016/j.conbuildmat.2017.09.162

Cited by 88 publications

(29 citation statements)

References 38 publications

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“…During the alkali activation, some of these particles were partially reacted ( Figure 2 b). New formed crystals were assigned to CSH/CASH and had foil-like shape, lamellar crystals [ 26 ]. When zeolitic waste was incorporated in the system, the particles of biomass bottom ash were almost not detected ( Figure 2 c).…”

Section: Resultsmentioning

confidence: 99%

Utilization of ZeoliticWaste in Alkali-Activated Biomass Bottom Ash Blends

et al. 2020

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This study aims to investigate the effects of ammonium-bearing zeolitic waste (FCC) on alkali-activated biomass bottom ash (BBA). FCC was obtained from the oil-cracking process in petroleum plants. In this study, two types of production waste were used: biomass bottom ash and ammonium-bearing zeolitic waste. These binary alkali-activated FCC/BBA blends were investigated using X-ray diffraction (XRD), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) methods. The compressive strength of the hardened samples was evaluated. The results show that the samples made from alkali-activated BBA biomass bottom ash had low (8.5 MPa) compressive strength, which could be explained with low reactive BBA and insufficient quantities of silicon and aluminum compounds. The reactivity of BBA was improved with incorporating zeolitic waste as an aluminosilicate material. This zeolitic waste was first used for ammonium sorption; then, it was incorporated in alkali-activated samples. Additional amounts of hydrated products formed, such as calcium silicate hydrate, calcium aluminum silicate hydrate and calcium sodium aluminum silicate hydrate. The silicon and aluminum compound, which varied in zeolitic waste, changed the mineral composition and microstructure of alkali-activated binder systems. NH4Cl, which was incorporated in the zeolitic waste, did not negatively affect the compressive strength of the alkali-activated BBA samples. This investigation proved that waste materials can be reused by producing alkali-activated binders.

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Section: Resultsmentioning

confidence: 99%

Utilization of ZeoliticWaste in Alkali-Activated Biomass Bottom Ash Blends

et al. 2020

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“…These EDX spectra are also indicative of the existence of C–A–S–H, which was the major hydration product of AAS [4,12]. C–A–S–H in AAS was pointed out to be more amorphous than C–S–H in hydrated Portland cement [43,44]. This clearly demonstrated that the AAS process could be strongly accelerated by heat-treatment curing despite the low Na 2 O concentration (4% by slag weight) of the activator.…”

Section: Resultsmentioning

confidence: 99%

Effect of Heat Curing Method on the Mechanical Strength of Alkali-Activated Slag Mortar after High-Temperature Exposure

2019

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The aim of this work was to study the mechanical strength and microstructure changes of alkali-activated slag mortar (AAS mortar) after being heat treated in the temperature range of 200–1000 °C. The AAS mortar was cured in the ambient condition (20 ± 5 °C, 60 ± 5% RH) (Relative humidity: RH) and high temperature condition (80 °C) for 27 days with three different heating regimes: curing in a dry oven, curing in sealed plastic bags, and in a steam environment. The activator for the AAS synthesis was a mixture of sodium silicate solution (water glass) and sodium hydroxide (NaOH) with a SiO2/Na2O weight ratio of 1, and a dosage of 4% Na2O by slag weight. Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) incorporated with energy-dispersive X-ray spectroscopy (EDX) were used to assess the mortar microstructure change. The results revealed that the curing method significantly affected the mechanical strength of AAS at temperatures lower than 800 °C. The heat treatment at late age of 28 days was more beneficial for compressive strength enhancement in specimens without using heat curing methods.

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“…Increasing of AASC's crack resistance in consequence of drying shrinkage mitigation can also be accomplished by increasing crystallinity of hydrated phases when using high-calcium additives such as ordinary portland cement clinker (further, OPC clinker) [18,46] or lime [47,48].…”

Section: Introductionmentioning

confidence: 99%

Enhancement of alkali-activated slag cement concretes crack resistance for mitigation of steel reinforcement corrosion

et al. 2020

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The paper is devoted to mitigation of steel reinforcement corrosion in alkali-activated slag cement (further, AASC) concretes, based on soluble sodium silicates (further, SSS's), obtained from high consistensy concrete mixes. Enhancement of AASC fine concretes crack resistance due to modification by complex shrinkage-reducing additives (further, SRA's) based on surfactants and trisodium phosphate Na3PO4 . 12H2O (further, TSP) was proposed for mitigation of steel reinforcement corrosion. SSS's were presented by sodium metasilicate (silica modulus 1.0, dry state) and water glass (silica modulus 2.9, density 1400 kg/m 3 ). In case of sodium metasilicate the application of SRA composition "ordinary portland cement clinker -TSP -sodium lignosulphonate -sodium gluconate" provides enhancement of crack resistance starting from early age structure formation with restriction of drying shrinkage from 0,984 to 0,713 mm/m after 80 d. The effect is caused by reduction of water and by higher volume of crystalline hydrates. In turn, SRA presented by compositions "TSP -glycerol" and "TSP -glycerol -polyacrylamide" provide enhancement of AASC fine concretes fracture toughness during late structure formation with increasing ratio of tensile strength in bending to compressive strength up to 37 -49 % if compare with the reference AASC when water glass is used.

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Hydration products, internal relative humidity and drying shrinkage of alkali activated slag mortar with expansion agents

Cited by 88 publications

References 38 publications

Utilization of ZeoliticWaste in Alkali-Activated Biomass Bottom Ash Blends

Utilization of ZeoliticWaste in Alkali-Activated Biomass Bottom Ash Blends

Effect of Heat Curing Method on the Mechanical Strength of Alkali-Activated Slag Mortar after High-Temperature Exposure

Enhancement of alkali-activated slag cement concretes crack resistance for mitigation of steel reinforcement corrosion

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