Research on flowable concrete

Three proprietary flowable concretes, considered to be suitable for repairs, were assessed using the approval tests specified in the Department of Transport Specification BD 27/86 (1986). The effects of temperature and water content on the flow properties were investigated together with variation in these properties from one batch to another in nominally the same material. Other aspects investigated include the effects of water-material ratio on the free drying shrinkage of the flowable concrete and the pull-off strength between the substrate and the replacement concrete. The material and mixing temperature was found to have significant influence on the flow properties as assessed by the approval tests. The temperature at which the concrete was poured had little influence on the distance of flow provided the materials were stored and mixed at or above 15 degrees C. The flow properties were found to improve with increasing water content up to a critical level; the additional water did not contribute to the flow. The flow properties between batches of the same material varied widely and confirmed the benefit of the current practice of testing every batch prior to its use. (A)