PARTICULARITIES OF HOT-IN-PLACE RECYCLING WITH CHANGING THE ASPHALT CONCRETE MIXTURE AGGREGATE GRADATION

Abstract

The hot in-place recycling (HIR) belongs to the successful strategies of asphalt concrete pavements rehabilitation that provides effective elimination of such surface defects as cracking, rutting, stripping, raveling, and bleeding including defects caused by the non-conformity of asphalt concrete to the standard specifications. The HIR technologies are divided into four methods: «Reshape», «Repave», «Remix», and «Remix Plus». Among those methods, «Remix» and «Remix Plus» are more complicated technologically and are connected with changing the composition of existed (old) asphalt concrete. The composition of existed asphalt concrete should be corrected through the addition some of new components (aggregates, asphalt binder, rejuvenating agent, or new hot-mixed asphalt concrete mixture) to the hot-milled old asphalt layer. This article is dedicated to the methods of calculation of new and recycled aggregate mixture gradation regarding to the Ukrainian standards. The proposed methods of calculation consider such main peculiarities of HIR-recycled materials and layer design as: 1) old asphalt concrete, particularly its aggregate parts, can used in a non-fractioned form only; 2) HIR-recycled asphalt concrete layer should be designed with or without the maximal layer thickness restriction. The proposed methods also give the possibility to correct the technological process if the calculated amount of new material necessitated to the correction of old asphalt concrete aggregate grading does not allow to maintain the projected layer thickness. The implementation of the proposed technique of calculation of aggregate grading with and without restriction of the maximal thickness of recycled asphalt concrete layer allows enhance quality of recycled materials and promotes the entire adaptation of HIR technologies to the Ukrainian standards. Keywords: hot in-place recycling of asphalt concrete, «Remix», «Remix Plus», recycled asphalt concrete mixture, correction of aggregate gradation.