Research at the Road Research Laboratory into the use of concrete for roads includes investigations into the properties of concrete and methods of designing a concrete mix, methods of controlling concrete quality, the design of concrete roads and bases, the efficiency of plant and methods of construction, and the maintenance of concrete roads. Those items where most development has taken place recently are reviewed in this paper. The review suggests that improved methods of measuring the workability and the durability of concrete may lead to better methods of mix design and suggests methods of testing by which the quality control of concrete may be improved. Changes in the design of conventional concrete slabs for heavily trafficked roads do not appear to be likely and new ideas are being considered such as progressed concrete and continuously reinforced slabs. Continuously reinforced concrete bases have given satisfactory performance for a number of years under a bituminous surfacing, and the amount of cracking in the surfacing has been less than that in the surfacing over some lease concrete bases; the effect of the mix proportions on the performance of lean concrete bases is being investigate. Experiments to examine methods of obtaining full compaction and good riding quality for conventional concrete slabs are described. The remaining problems are concerned with the compaction of lean concrete and the provision of a surface on a concrete slab which will have a high skidding resistance at high speed. Finally methods of repairing a spelled concrete surface are given.
Samenvatting