MEASUREMENT OF IMMEDIATE ASR EXPANSION OF STEAM CURED MORTAR BARS

In order to measure any expansion of mortar bars induced as a result o f a steam curing cycle after the brief (6-hour) pre-steaming hydration period usually allowed, a special procedure was designed so as to ena ble a base length measurement to be made at 6 hours, i.e. before the m ortar bar had gained enough strength to permit removal from the mold. This procedure involves use of a specially designed Teflon mold which supports the mortar bar during its initial length measurement and thro ugh the steam curing cycle, but permits expansion to take place with o nly minimal frictional resistance. Alkali-silica reactive mortar bars were shown to undergo significant reaction and permanent expansion dur ing the steam curing process.