Question

A highway contractor has opened a cut in fine silty sand (SM). Because of the cut location and lack of drainage, surface water has drained into the cut, leaving the material very wet. Rubber-tired scrapers are hauling material from the cut to an adjacent fill. The material is being placed in the fill in 20 to 25cm lifts and compacted by heavy sheep foot roller towed by a crawler tractor. It is apparent that the specified compaction (95% of standard AASHTO density) is not being attained. The sheep foot roller not “walking out and scraper tires are causing the compaction problem? What would you suggest to the constructor to improve the compaction process? Ideally, concrete should be poured at temperatures between 16°C and 38°C.

Answer 1