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Slag fine aggregates are by-products of electric arc furnace steelmaking. After the slag fine aggregates are pre-treated, they can replace natural fine aggregates in some cases. In this study, the researcher used slag aggregates, water quenched stove powder, sodium hydroxide solution, and sodium silicate solution (water glass) to activate the slag cementation activity. The objective was to explore the effects that the alkali activated furnace powder cementing material have on the new mix and the hardening properties under different alkali equivalent volumes, alkali modulus ratios, and water-cement ratios. In this study, the researcher referred to the curing environment of ASTM C1260 to soak the slag aggregate specimen in 80 ℃ 1N concentration NaOH solution. After 14 days, the researcher removed the test specimen and measured the amount of expansion. Finally, the researcher used the preferred alkali activation ratio to produce high-pressure concrete bricks and investigate the performances of the alkali activation technology for recycled products.
The study results indicated that: (1) The condensation time of alkali activated mortar would shorten as the alkali equivalent volume is increased. (2) When the alkali activated mortar of the slag fine aggregates has the alkali equivalent volume of 5% and alkali modulus ratio of 0.75, the compressive strength is greater than the cement mortar; the higher the alkali activator concentration, the better the compressive strength development for the mortar. (3) The alkali activation technology can have an expansion suppressing effect for the specimen soaked in the 80 ℃ 1N concentration NaOH solution. (4) When slag aggregates are used to make concrete bricks, the bricks would achieve CNS 13295 specification C-grade compliant if the alkali equivalent volume is 6% and the alkali modulus ratio is 1.75. | en_US |