Rollcrete Bas – CBGB for the Tag Motorway in Turkey

Rollcrete Base - also called Cement-sound Granular Base (CBGB) - is basically a dry material bound by Portland cement, placed using an adapted asphalt paver, and vibrated externally. One of the first applications of rolicrete for the Trans European Motorway project was on the Tarsus - Adana - Gaziantep (TAG) section in Southern Turkey. The aggregate used was crushed limestone with a maximum size of 37.5 mm and up to ten percent of fines. A laboratory mix was designed, to give an unconfined compressive strength (UCS) of between 3.5 and 5.5 N/mm2 at seven days. This paper investigates the worksite mix formula (WMF) that would provide the required strength and would determine the water - dry density relationship to control compaction on site. Test results indicated that a Portland cement content of only about 1.8% by weight of mix was sufficient to obtain a seven day UCS of 4.5 N/mm2 (mean of the minimum and maximum) at an optimum water content (OWC) of 5.2% and a maximum dry density (Ydmax) of 2.342 gr/cm3. However UCS test results of the working mix were generally somewhat higher than the design mix, although still within the required limits.