digilib@itb.ac.id +62 812 2508 8800

1992 Teddy Erwanto
PUBLIC Alice Diniarti

Currently access road construction for oil field exploration carried out by LASMO in Riau Province, Sumatra, involves use of crusher run granite transported in from Karimun Island to the east. Various ways of possibly reducing the cost of the roads without incurring an unacceptable loss in performance have been under consideration, including partial replacement by PFA, the object of this study. PFA was obtained from Suralaya Power Station, the source of the parent coal being from Bukit Asam in Sumatra. After initial classifications it was then mixed in varying proportions with the Karimun crusher run granite. The various mixes were then subject to a number of tests involving grading specific gravity, compaction using both standard and modified conditions, and CBR strength testing. Effects such as delay in compaction after initial mixing, soaking and curing time were evaluated. It was found that the maximum dry density was achieved at a PFA content of 5 % , this being ascribed to the PFA just filling void spaces, additional quantities of PFA thereafter replacing the heavier granite and causing a reduction in maximum dry density. The corresponding optimum moisture content was 5.5 The strongest mix, in term of CBR strength, was obtained when the PFA content was 15 % with a minimum curing period of 14 days. The PFA was found to exhibit beneficial pozzolanic behaviour. The heavier compactive effort, i.e modified compared with standard, produced a higher strength . Soaking for 4 days resulted in a loss in strength. Little difference in strength resulted whether method B or method I) of the standard tests designation was used , and delay in compaction after initial mixing (for 24 hours) was not found to be significant in term of CBR strength. Increasing the number of blows in compaction caused an increase in CBR and dry density values.