The influence of curing conditions and alkaline activator concentration on elevated temperature behavior of alkali activated slag (AAS) mortars

Nasr, Danial; Pakshir, Amir Hossein; Ghayour, Hossein

doi:10.1016/j.conbuildmat.2018.09.099

Cited by 71 publications

(26 citation statements)

References 39 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Alkali activation technology offers the possibility to utilize large amounts of aluminosilicate-rich secondary products such as fly ash from thermoplants [1,2,3], slag from metallurgical processes [4,5] and waste glass [6] for a useful new group of building products. Steel slag-based alkali activated materials (AAM), have a high mechanical strength, show good fire resistance and high thermal resistance at elevated temperatures, and, in the case of low density, they further exhibit low thermal conductivity [7].…”

Section: Introductionmentioning

confidence: 99%

“…Besides the reactivity potential of the slag with an alkali activator, which depends on the chemical composition of the slag and the amount of aluminosilicate amorphous phase, surface morphology and particle size distribution, the addition of an alkaline solution and ageing and curing conditions should be taken into account. The development of strength in slag-based AAMs with respect to curing regimes has been studied and presented in various publications [4,19,23,24,25]. Curing at elevated temperatures can greatly affect the chemical reaction with the gel formation and geopolymerization.…”

Section: Introductionmentioning

confidence: 99%

“…Water absorption is greater in the case of water type curing prior temperature exposure, as authors suggests that is due to the large pore formation resulting from accelerated hydratation and faster geopolymerization. Samples cured at higher temperatures shows the increased porosity in comparison to ambient cured samples [4]. Altan et al suggested that when alkali activated slag mortars, using alkali hydroxide and a sodium silicate activator, were cured at room temperature (23 °C) for a sufficiently long time (70 days), an equal or higher strength could be attained compared to those cured at 80 °C for only 4 days [23].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The Potential of Ladle Slag and Electric Arc Furnace Slag use in Synthesizing Alkali Activated Materials; the Influence of Curing on Mechanical Properties

et al. 2019

View full text Add to dashboard Cite

Alkali activation is studied as a potential technology to produce a group of high performance building materials from industrial residues such as metallurgical slag. Namely, slags containing aluminate and silicate form a useful solid material when activated by an alkaline solution. The alkali-activated (AA) slag-based materials are promising alternative products for civil engineering sector and industrial purposes. In the present study the locally available electric arc furnace steel slag (Slag A) and the ladle furnace basic slag (Slag R) from different metallurgical industries in Slovenia were selected for alkali activation because of promising amorphous Al/Si rich content. Different mixtures of selected precursors were prepared in the Slag A/Slag R ratios 1/0, 3/1, 1/1, 1/3 and 0/1 and further activated with potassium silicate using an activator to slag ratio of 1:2 in order to select the optimal composition with respect to their mechanical properties. Bending strength of investigated samples ranged between 4 and 18 MPa, whereas compressive strength varied between 30 and 60 MPa. The optimal mixture (Slag A/Slag R = 1/1) was further used to study strength development under the influence of different curing temperatures at room temperature (R. T.), and in a heat-chamber at 50, 70 and 90 °C, and the effects of curing time for 1, 3, 7 and 28 days was furthermore studied. The influence of curing time at room temperature on the mechanical strength at an early age was found to be nearly linear. Further, it was shown that specimens cured at 70 °C for 3 days attained almost identical (bending/compressive) strength to those cured at room temperature for 28 days. Additionally, microstructure evaluation of input materials and samples cured under different conditions was performed by means of XRD, FTIR, SEM and mercury intrusion porosimetry (MIP).

show abstract

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

The Potential of Ladle Slag and Electric Arc Furnace Slag use in Synthesizing Alkali Activated Materials; the Influence of Curing on Mechanical Properties

et al. 2019

View full text Add to dashboard Cite

show abstract

“…Rashad et al (2016) found an enhancement in the compressive strength of AAS pastes activated with Na 2 SO 4 after exposure to 200-600 o C, whilst exposure to 800 o C decreased it. Nasr, Pakshir, & Ghayour, (2018) found an enhancement in the compressive strength of AAS mortars, cured at ambient temperature, activated with 2% Na 2 O after exposure to 200-600 o C. Other studies found higher compressive strength of slag activated with Na 2 SO 4 after exposure to 200-600 o C (Rashad et al, 2012). From the previous discussions, it can be concluded that the behaviour of AAS system under thermal loads could be affected by many factors such as curing conditions (Nasr et al, 2018;Türker et al, 2016), activator type (Cheng & Chiu, 2003) and activator concentrations (Nasr et al, 2018;Rashad et al, 2012;Rashad et al, 2016).…”

Section: The Response Of Hardened Paste Mixtures To Elevated Temperatmentioning

confidence: 99%

An investigation on alkali-activated slag pastes containing quartz powder subjected to elevated temperatures

Rashad

2020

rdlc

View full text Add to dashboard Cite

In this work, the opportunity of employing crystalline silica in the form of quartz powder (QP) to increase the fire resistance of alkali-activated slag (AAS) has been explored. The ground granulated blast-furnace slag (designated as slag) was partially replaced with QP at levels changed from 5% to 30% with a step of 5%, by weight. After curing for 28 days, the specimens were subjected to elevated temperatures varying from 400 o C to 1000 o C with a step of 200 o C for 2 h. The compressive strength before and after heating was measured. The new formed phases were evaluated by using Xray diffraction (XRD), whilst the decomposition phases were evaluated by using thermogravimetric (TGA). The changes in the microstructures were monitored by using scanning electron microscopy (SEM). The results showed a positive effect of incorporation of QP, up to 30%, in AAS system before and after exposure to elevated temperatures.

show abstract

“…The final properties of AAA are influenced by chemical composition of precursors and activators and by curing conditions. Thermal curing has a positive effect on compressive strength [3]. Initial curing at 25 °C does not though lead in some cases to formation of reaction products and at least the curing temperatures of 40 °C and higher are necessary [4].…”

Section: Introductionmentioning

confidence: 99%

Monitoring the course of early-age reactions in alkali activated aluminosilicates

2019

View full text Add to dashboard Cite

In this paper the reaction heat development of alkali activated aluminosilicates is studied by an isothermal heat flow calorimeter. The highest reaction activity is observed during two hours after mixing. The hydration heat power at early time is influenced mainly by the composition of tested mixtures involving ceramic dust as precursor and different amounts of sodium hydroxide and water glass as activators and by temperature.

show abstract

The influence of curing conditions and alkaline activator concentration on elevated temperature behavior of alkali activated slag (AAS) mortars

Cited by 71 publications

References 39 publications

The Potential of Ladle Slag and Electric Arc Furnace Slag use in Synthesizing Alkali Activated Materials; the Influence of Curing on Mechanical Properties

The Potential of Ladle Slag and Electric Arc Furnace Slag use in Synthesizing Alkali Activated Materials; the Influence of Curing on Mechanical Properties

An investigation on alkali-activated slag pastes containing quartz powder subjected to elevated temperatures

Monitoring the course of early-age reactions in alkali activated aluminosilicates

Contact Info

Product

Resources

About