The objective of this investigation is to assess the effect of the alkali silica reaction (ASR) on the residual anchorage bond strength of both plain bar and ribbed bar (deformed type 2) steel reinforcement in concrete. Only one bar diameter (16 mm) and one grade of concrete (55 N per square mm) was considered. Other variables considered were: (a) reactive and non-reactive concrete; and (b) confinement of reinforcement and no confinement. Two types of test specimen were used: (a) cover region; and (b) core cover region. For the reactive specimens, ASR was introduced by the addition of alkalis to give a total alkali content of 7 kg/cubic metre sodium oxide equivalent. All specimens were stored in racks in an insulated conditioning tank and kept at 20 degrees C for at least 28 days, and 38 degrees C thereafter. The specimens were tested when the level of expansion in the reactive concrete was around 1500 microstrain (restrained) and 4000 microstrain (unrestrained). ASR does not appear to have a detrimental effect on the bond strength of plain bars with links, for either top or bottom cast. There is a substantial increase in the bond strength for top cast plain bars without links, but the corresponding bond strength of bottom cast bars is approximately halved. ASR reduces the bond strength of ribbed bars without links for low levels of cover. The change in strength is not statistically significant. ASR also reduces the bond strength of ribbed bars in the core region but this reduction cannot be quantified. For phase two of this study see IRRD 836568.

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