Development of a guideline to determine structural capacity of demolition waste as a road construction material

Abstract

The use of demolition waste as pavement base material is a promising but unproven technique for road rehabilitation and construction. A survey was conducted by Building Economics Department of University of Moratuwa found that demolition waste is infrequently used in this application due primarily to a lack of practical knowledge about the engineering properties of the material. Therefore, this research was aimed at evaluating the physical properties, strength parameters, and durability characteristics of demolition waste to use as pavement base material. The study included extensive laboratory and prototype model testing. Laboratory tests included flakiness index value, elongation index, aggregate impact value, Los Angeles abrasion value test, California bearing ratio, unconfined compressive strength and durability evaluations. Prototype modeling was utilized to compare demolition waste with respect to general base materials. It included a plate load test and dynamic cone penetrometer. The prototype model demonstrated that the demolition waste base layer was susceptible to stiffness changes due primarily to changes in moisture. Prototype model results have been verified using ‘Everstress’ back-calculation software and it can be shown that the layer coefficient of CCM is equivalent to 0.134. And also this material shows a very high variability with respect to conventional base materials i.e. DGAB. Therefore it is recommended to use this material as a base material for a traffic load of 20kN or less. And it will perform a strong correlation as given in design charts & tables. Finally it was possible to evaluate a structural capacity of demolition waste and develop a design chart to replace dense graded aggregate base course from demolition waste base layer for construction of roads. Therefore it is recommended to introduce demolition waste material instead of conventional base material based on the developed design guidelines.