Investigating the effect of using recycled waste concrete powder (RWCP) on the performance of thin layer surface treatment: Microsurfacing

Considering the importance of roads and highways in creating communication between different areas, and the issue of repair, maintenance and management of roads has always been among the main concerns of the countries. Microsurfacing is among the best methods for the preventive maintenance of roads. On the other hand, in the present age, production of considerable amounts of construction waste (CW) has turned into a major environmental issue. Thus, the use of recyclable CW in pavements could help with the preservation of nonrenewable materials and at the same time reduce environmental problems. The present research attempts to implement recycled waste concrete powder (RWCP) in the mix design of thin layer surface treatment (microsurfacing) to evaluate its performance. In this respect, first the chemical and physical characteristics of the used materials in asphalt were investigated. Next, for evaluating the microsurfacing mixtures use was made of five different microsurfacing mixtures containing 0, 25, 50, 75, and 100% RWCP filler. Assessment of RWCP containing microsurfacing mixtures was done by performing the wet cohesion test, wet track abrasion test (WTAT), loaded wheel-sand adhesion test, and loaded wheel-displacement test according to ISSA A143 Guideline. Then using the FTIR, XRF, and FESEM-EDS tests, the structure, chemical bond, and functional groups, constituting components, and shape and surface of the grains were investigated, respectively. The results revealed that RWCP due to containing large amounts of CaO and SiO2, also having a rough surface compared to that of the natural filler could improve the microsurfacing performance. For example per 9% bitumen, the mixture containing 75% RWCP causes an increase of cohesion at 30 and 60 min durations by 23.4 and 22.7%, respectively. Also, it improves resistance against abrasion by 45%, reduction of mixture bleeding by 18%, and increases resistance against vertical and lateral displacements by 20 and 16%. In addition, considering the analysis of variance (ANOVA) results, all the three factors i.e. bitumen, RWCP filler, and interaction of materials were effective on the microsurfacing performance.