Compressive Behaviour of Alkali Activated Slag Concrete and Conventional Concrete under Heat Curing and Ambient Curing Regimes

Alkali-activated slag has a higher resistance against exposure to high temperature compared to ordinary Portland cement concrete. Nevertheless, its mechanical properties are also deteriorated due to partial decomposition of the C-A-S-H matrix. This paper investigates the effect of various curing regimes applied to the samples which were exposed to temperature 200–1200 °C on the mechanical properties and microstructure of the alkali-activated slag/limestone blends. The amount of limestone was 15% from the mass of slag. On set of specimens was treated on air at laboratory conditions, the second set was immersed in water and the last was treated stored in humid chamber with 95% relative humidity for the period of 60 days. The results showed that water curing has a strong positive influence on the compressive as well as flexural strength of the specimens exposed to temperatures up to 600 °C. Specimens which were exposed to 800 and 1000 °C showed the best performance after treatment in humid chamber, and after exposure to 1200 °C the best compressive strength exhibited the air cured samples.

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Properties and hardening mechanism of alkali activated slag based hydrophobic coating at ambient curing condition

Materials Research Express ◽

10.1088/2053-1591/aaf950 ◽

2019 ◽

Vol 6 (5) ◽

pp. 055505

Author(s):

Jinsong Liu ◽

Zhihua Pan ◽

Xuebing Wang ◽

Saisai Xu

Keyword(s):

Alkali Activated Slag ◽

Hardening Mechanism ◽

Hydrophobic Coating ◽

Curing Condition ◽

Activated Slag ◽

Alkali Activated ◽

Ambient Curing

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

Materials ◽

10.3390/ma12111789 ◽

2019 ◽

Vol 12 (11) ◽

pp. 1789 ◽

Cited By ~ 1

Author(s):

Tai Thanh Tran ◽

Hyuk Kang ◽

Hyug-Moon Kwon

Keyword(s):

High Temperature ◽

Mechanical Strength ◽

Weight Ratio ◽

Sodium Silicate Solution ◽

Silicate Solution ◽

Alkali Activated Slag ◽

Heat Curing ◽

Curing Method ◽

Activated Slag ◽

Alkali Activated

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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