Study of the effect of the curing protocol, the RAP source, and the compaction method on cold recycled mixes with foam mechanical characteristics

Abstract

Cold mixtures have been burgeoning in the last decades and assisted in many pavement constructions. Environmental and economical advantageous justify all the investment and scientific efforts to develop this method. However, behaviour complexity of cold mixtures restricts its application. Due to its characteristics and performance high dependency to ambience and numerous factors in pre-production, production and post-production phase, quality control is necessary during different stages of production. On the other hand, utilization of foam bitumen as binder casts even more complexity on it, which requires a more meticulous construction process. Although, RAP usage strategy in cold mixtures’ structure helps to provide sustainability aspects more than before, however, the different characteristics of RAP and raw material requires newer understanding. Due to all this sophistication associated with cold mixtures production, uniform standards and production protocols are hard to establish, so are rare to find. Curing, as one of the main efficacious production stages, is found to be crucial and investigated in this study. Final characteristics and engineering properties are tied to this part of the process and it is mainly because of the evolutive behaviour of the cold mixtures. Moreover, actual field-extracted specimens yield different characteristics than laboratory fashioned ones and it is a witness of hardship of field condition simulation in the lab. In present writing, this part of a cold mixtures production process is investigated, and it proposes a curing method to simulate the realistic field condition and minimize the existing gap between lab and field specimen test results to improve real condition reflection in the laboratory. Different RAP sources and different compaction processes are investigated as well to cast more lights on the issue. Applying the new curing method in this study resulted in stiffer specimens which are up to 2 times stiffer than the specimens with conventional curing. Moisture resistance is also improved and ITR results are, on average, changed by 10% in most of the cases. Fracture resistances, which are tested through SCB test, are also changed. However, these changes in SCB, ITS and ITSM result are not always consistent.

Date	16 Dec 2020
Original language	American English
Awarding Institution	École de technologie supérieure
Supervisor	Alan Carter (Supervisor) & Daniel Perraton (Co-supervisor)