New Laboratory Mix Methodology of Microsurfacing and Mix Design

Microsurfacing was introduced in Germany, Spain, and France since 1976 and in the United States in 1980 (NCHRP 411, 2010). In India, it was introduced only in 1999-2000 (Yala construction, 2011) under the brand name, Macroseal by Yala construction and Elsamex SA, Spain. Established mix methodologies (Kharagpur and TxDOT methods) were evaluated and balling appeared to be still present with this method. A different mix methodology was explored and observed to have reduce or solve balling, the common problem of mixing coarse, fine aggregates with emulsion. The mix methodology was developed for type II, and type III gradation for microsurfacing and was adopted for the study. By adopting the mixing methodology, break time, setting times and consistency test were evaluated with variable water content 5%, 7%, 8% 10%. The consistency value observed was between 2cm to 4cm and that microsurfacing of Type II and III satisfies all the criteria given in Technical Bulletin of ISSA.Modified marshal test was also carried out to determine the optimum residual bitumen content. It was found that at 4% air voids the optimum residual bitumen content for Type III gradation is 10% and for Type II gradation is 7.7% and at these optimum contents, flow, air voids, VFB and VMA satisfy the requirement of Marshall Criteria.