This paper describes the low cost improvements to a low to medium volume road in Sri Lanka completed in June 1988, featuring the construction of a 100 to 150mm thick gravelly soil base having a four day soaked CBR value of not less than 25 followed by a surface dressing of a prime coat and a sand seal. The purpose of this study was to look into the feasibility of replacing a subbase of thickness 150mm and a dense graded aggregate base of thickness 150mm followed by a prime coat and a single surface dressing in the normal design with the above named construction. This paper also describes an innovative method of obtaining a base course with material having CBR not less than 25 by using 2 to 3% lime and 10 to 25% sand. The method described in this paper has proved successful to date, but required regular maintenance of surfacing and a resurfacing every 2-3 years.It is an useful method of construction of low to medium volume roads, in territories of countries where dry climatic conditions prevail most of the year and labour is cheap and freely available for maintenance. (A)
Abstract