Quantifying effects of laboratory curing conditions on workability, compactability, and cohesion gain of cold in-place recycling

Abstract

Cold in-place recycling (CIR) is a pavement rehabilitation treatment which has shown promise in terms of environmental benefits, cost savings, and successful performance. Current procedures for asphalt emulsion CIR mix design, AASHTO PP86 and AASHTO MP31, address mixture proportion selection and final performance prediction but do not consider performance of the material during the construction process. This research proposed the addition of three intermediate stages into asphalt emulsion CIR mix design: workability, compactability, and cohesion gain. Equipment commonly available in asphalt laboratories was evaluated for ability to quantify workability, compactability, and cohesion gain by measuring differences in performance due to changes in curing conditions. Cure temperature generally had a more significant influence on test results than cure time. Superpave Gyratory Compaction (SGC) metrics were recommended for quantifying workability and compactability. The direct shear test showed promise for quantifying cohesion gain moving forward based on agreement with the triaxial test.