Effect of Cement Content on Cracking Resistance of Full-Depth Reclamation Materials Using the Semicircular Bending Test

Abstract

Abstract Full-depth reclamation (FDR) materials are a type of cold-recycled bituminous mixes that are composed of reclaimed asphalt pavement (RAP) and virgin aggregates. FDR is often treated with a binder in order to obtain cohesion. It is common to use bitumen emulsion, foam asphalt, and cement. In many parts of the world, when bitumen emulsion or foamed asphalt is used, cement is added as a cobinder to accelerate the curing process and cement hydration produces calcium silicate hydrate that may contribute to mechanical and durability properties. However, because cement creates fragile bonds, too much cement could be problematic for FDR. The objective of this study is to evaluate the effect of the cement proportion on fracture resistance of the FDR materials containing 50 % RAP and 50 % aggregate. Five proportions of the cement were added to the mixtures: 1, 2, 3, 4, and 5 %. Semicircular bending (SCB) tests were used to evaluate the cracking resistance of the mixture using the strain energy release rate (Jc). A total of 120 semicircular specimens were tested at intermediate temperatures, where 60 specimens were tested in wet condition to investigate the moisture sensitivity. The flexibility index (FI) and the cracking resistance index (CRI) were used to analyze the flexibility and brittleness of the mixtures. Results have shown that the FDR mixtures are more resistant to cracking as the cement content increases. The FI values, ranging between 1.32 and 4.74, revealed that a high percentage of added cement (4 and 5 %) contributes to making the samples behave like brittle mixtures. The CRI results showed a similar trend as the FI results.