LENGTH EXPANSION AND CRACKING OF PLAIN AND REINFORCED-CONCRETE PRISMSDUE TO ALKALI-SILICA REACTION

Measurements of length expansion and observations of cracking of plain and reinforced concrete prisms with varying sizes and amount of reinf orcement due to alkali-silica reaction (ASR) are presented. Ends of th e prisms were sealed, to make the data relatable to existing structura l members. The specimens were made with either reactive or non-reactiv e aggregates and immersed in an alkali solution for one year to accele rate ASR. Visible cracks appeared on reactive specimens after four mon ths of conditioning, when length expansion due to ASR was about 400 mi crostrain. Expansion of the prisms that contained longitudinal bars wa s greatly reduced by the reinforcement, and the dominant cracking was oriented in the direction parallel to the reinforcement. Strain of bar s caused by ASR was close to yield. The effect of expansion and cracki ng due to ASR on structural behavior of reinforced beams and on mechan ical properties of companion cylinders which accompanied these prism t ests is reported separately.(1)