Mechanical mechanism for expansion and crack of mortars containing basic oxygen furnace slag sand

Abstract

Basic oxygen furnace slag is the main steel slag in China. This study aims to set forth the mechanical mechanism for expansion and crack of mortars made with basic oxygen furnace slag sand from compressive strength, linear expansion rate under hot-water curing condition and microscopic test. The results indicated that the expansion rate had some correlations with the strength and the rapid increase of expansion rate accompanied the remarkable decrease of compressive strength for mortars made with basic oxygen furnace slag sand. However, the expansion curve was similar to a horizontal line without decrease of compressive strength for mortars made with standard sand. Tiny cracks arose from hydration of mottled particles were the main reason resulted in the volume unsoundness of mortars made with basic oxygen furnace slag sand according to the result of XRD and the characteristics of crack. Model of expansion and cracking of mortars made with standard sand was built at last.

Keywords:

• Compressive strength
• Basic oxygen furnace slag
• Linear expansion rate
• Stress concentration
• Mottled particles