Estudo da aderência do microrrevestimento asfáltico a frio utilizado na manutenção preventiva de pavimentos.

Abstract

Asphalt micro-surfacing is a technique used in the preventive/corrective maintenance of medium to heavy-traffic roads. However, pavement treated with this technique has shown early defects that affect road comfort and safety. One of the possible triggers could be poor adhesion between the micro-surfacing and the old pavement. In this respect, the placing of a tack coat in maintenance activities aims to mitigate/retard the onset of these defects, as this layer has the function of ensuring that the structure works as a monolithic system, hindering the onset of early cracking due to fatigue or slippage. The simple and direct shear tests are the most recommended of the methodologies available for assessing the adhesion properties of pavements. The Leutner adhesion test is a direct shear test between pavement layers and has shown itself to be one of the most promising, as it can be used on thin layers. Therefore, this method was chosen to conduct the present research that sought to investigate the factors influencing the adhesive behavior of micro-surfacing applied to flexible or rigid pavements. Shear strengths were analyzed at interfaces without a bond coat and with a bond coat using RR-1C, RR-2C, and RC1C-E emulsions for three application rates (0.5 l/m2, 0.75 l/m2, and 1.0 l/m2), and for both pavement types. The tests were performed at three temperatures (10°C, 30°C, and 50°C). The experimental design of the research was performed using a central composite design (factorial design) and a completely randomized design (ANOVA with two factors). It was found that temperature is the most influential variable on the micro-surfacing adhesive behavior.

The surface type and treatment (without and with bond coat) also influence the micro- surfacing adhesive behavior. The application rate did not influence the shear strength

at the interface of flexible or rigid pavements treated with this asphalt mixture, except for the scenario using RR-2C emulsion on the rigid pavement. According to the results gathered in this research, micro-surfacing would not be suitable for most Brazilian regions due to the high temperatures. An alternative for improving the adhesive behavior of flexible pavements is incorporating a bond coat, in which case the most recommended emulsions are RR-2C and RC1C-E. Improvements can be made for rigid pavements with any emulsions studied in this research.