NASCIMENTO, M. V.; DAS VITORIAS DO NASCIMENTO, MARIA.; http://lattes.cnpq.br/1173283848995598; NASCIMENTO, Maria das Vitorias do.
Resumo:
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.