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Nowadays, significant research effort is being dedicated to explore environmentally friendly block materials with high strength and high-temperature resistance. Ground-granulated blast-furnace slag (GGBFS) is produced during the iron smelting waste process and can be activated to form the environment friendly alkali-activated slag cementitious material (AASCM) when mixed with alkaline activator. The aggregate consists of particles of different sizes, which are crushed and are screened using the paste of AASCM. In this study, the compressive strengths of 234 block specimens during and after high-temperature treatment were investigated. The test results showed that the compressive strength of the blocks gradually decreased slowly when the temperature was lower than 600°C, and decreased rapidly when the temperature was above 600°C. The reduction coefficient of compressive strength of the blocks during and after 900°C exposure were 14.2% ~ 28.1% and 15.3% ~ 28.7% of the ambient temperature strength, respectively. The steel fibre reduced the compressive strength loss of the blocks during and after the high-temperature exposure. With the increase of temperature, the steel fibre lost its effect gradually. Moreover, the compressive strength of the block after the high-temperature treatment was higher than that during the treatment when the strength level and temperature remained constant, the ratio was between 0.99 and 1.14. The high-temperature strength loss of the alkali-activated slag crushed aggregate concrete block was lower than that of the alkali-activated slag ceramsite concrete block. The fitted equations for calculating the compressive strength during and after the high-temperature treatment provided a basis for evaluating the fire resistance of this new type of block. The microstructure and composition of the block were analysed through scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results provide theoretical basis and data support for the application of AASCM in masonry blocks in high-temperature environments. [ABSTRACT FROM AUTHOR]

The use of blast furnace slag improves resource utilization and supports the achievement of sustainable development goals. The use of alkali-activated slag cementitious material (AASCM) provides a new direction for improving the fire resistance of masonry structures. The masonry investigated in this study was alkali-activated slag crushed aggregate concrete masonry (ASCCM) in which aggregates of blocks and mortars were crushed and screened using AASCM paste specimens. The compression behavior of 12 specimens during and after exposure to high temperatures, specifically 300, 500, 600, 700, 800, and 900°C was investigated. The specimens were maintained under the target temperature for 2 h. The compressive strength and axial deformation of the specimen were recorded. The compressive strength losses during exposure to 300, 500, 600, 700, 800, and 900°C are 15.9, 20.3, 38.3, 43.9, 63.3 and 73.8%, respectively. The compressive strength losses after exposure to 300, 500, 600, 700, 800, and 900°C are 10.6, 15.8, 34.0, 37.2, 58.6 and 72.2%, respectively. The rate of loss in elastic modulus is greater than that in compressive strength. During exposure to 300, 500, 600, 700, 800, and 900°C, the loss rates of elastic modulus are 56.5, 74.4, 83.3, 86.3, 92.9 and 93.9%, respectively. After exposure to 300, 500, 600, 700, 800, and 900°C, the loss rates of elastic modulus are 49.6, 67.3, 77.5, 82.0, 90.7 and 94.5%, respectively. The peak compressive strain values are 9.9 and 11.1 times that at room temperature. Equations for calculating the compressive strength, elastic modulus, peak compressive strain, and ascending section curve of the stress–strain relationship with temperature were derived. The research results provide a new choice for high temperature resistant masonry materials, and provide theoretical basis and data support for the application of AASCM in masonry structures in high-temperature environments. [ABSTRACT FROM AUTHOR]

• Bond properties of alkali-activated slag concrete hollow block masonry are studied. • Shear strength, flexural strength and axis tensile strength of masonry were tested. • The effect of mortar strength grade on bond properties of masonry was evaluated. • Higher mortar strength lead to higher bond strengths of masonry. • Practical equations were developed to estimate mechanical properties of masonry. The shear, flexural and axial tensile bond strengths of alkali-activated slag concrete hollow block (AASCHB) masonry layered with alkali-activated slag (AAS) mortar were investigated in this study. A comprehensive experimental investigation was conducted to assess the effect of the AAS mortar strength on the bond characteristics of the masonry. The bond strength of the AASCHB masonry was found to be directly related to the compressive strength of the AAS mortar, where higher compressive strength led to higher bond strength. In addition, new expressions for the bond strength were developed for AASCHB masonry based on the compressive strength of AAS mortar. [ABSTRACT FROM AUTHOR]