Research On Reuse Of Old Pavement Materials In The Base

When the cement stabilized stone pavement can't continue to use due to the damage, overlay the asphalt layer is one of the most popular methods, one of the most key problem is treatment of the old pavement materials. Corresponding to the actual project, this paper investigate the reuse of old pavement materials in the base, break up the old pavement, make full use of primary materials, then spray water and spread stone crumbs, when the layer is steady, spread bitumen surface on the base. This technology has several advantages such as make the old pavement steady, improve the base strength and delay reflection crack in the face layer, and bring huge economy and society benefit.Firstly, treatments of old materials were analyzed, different kinds of treatment were compared, and the rubblization technologies used in and abroad were surveyed. After analysis, the old pavement still has a certain degree of strength, and the strength is uniform, it can meet new layer's bearing request, furthermore, rubblization can avoid reflection crack in the new layer. Pavement in the mountains due to its lower strength, the monotype impact breaker is suitable, which can decrease the damage to base and affiliate constructions by major breaker.Secondly, by analyzing the loss of strength in the base and reflection crack occurs, combining research data in and abroad, the size of broken stones was proposed. Benkelman beam test was used to detect pavement deflection, and rebound modulus was calculated, the modulus of broken layer is in the size 400-800MPa, which is satisfied to be flexible base.Thirdly, the performance of broken stone materials was investigated by CBR value, unconfined compress strength, rebound modulus, permanent deformation. Results show that the intensity of reused materials decreased to some degree, and packed with cement slurry. CBR value, strength and modulus are lower than fresh materials, rebound modulus is no more than 100MPa, and the rate of permanent deformation is about 1%.Finally, according to the actual project application, construct technics of rebuild base was proposed, which will help the technical extend in actual application.