Effect of cooling technique of blast furnace slag on the thermal behavior of solid cement bricks

Sustainable construction has become a challenge in the engineering community. Some of the important elements in this respect are the reduction of the consumption of energy and natural resources. Big attention is being focused on the recycling of wastes/by-products to produce more sustainable building materials. Blast furnace slag (BFS) is a by-product generated from the production of pig iron in the blast furnace. In Egypt, there are two main types of BFS depending on the used cooling technique; air-cooled slag (ACS) produced by slow cooling of BFS under atmospheric conditions and water-cooled slag (WCS) produced by water quenching. This paper examines the effect of using ACS and WCS without any processing to substitute natural sand (NS) in solid cement bricks. The behavior of the bricks was evaluated at ambient temperature and after exposure to elevated temperatures up to 800 °C. Five mixes were prepared: M1 is the control mix without sand substitution, M2 and M3 are mixes including 50 and 100% replacement of sand with ACS, respectively. Mixes M4 and M5 contain 50 and 100% replacement of sand with WCS, respectively. Results indicate the possibility of recycling ACS and WCS, without processing to conserve energy, as fine aggregate in bricks manufacturing. The use of ACS resulted in a higher deterioration after exposure to elevated temperatures, although it increased the compressive strength of the unheated specimens. On the other hand, the bricks containing WCS are thermally more stable than NS and ACS bricks.