EFFECTS OF MINERAL FILLERS ON THE STABILITY AND VOLUMETRIC PROPERTIES OF ASPHALT

Abstract

The study was carried out to evaluate the effect of mineral fillers on the stability and volumetric properties of asphalt. The mineral fillers used were granite dust, Portland cement and lime. The optimum binder content was determined from asphalt mix produced with 100% granite dust at bitumen content ranging from 5%, 5.5% 6%, 6.5% and 7% by weight of the aggregate and the predetermined optimum binder content was used for production of asphalt mix with mineral fillers such as 100% lime, 100% cement, 50% granite dust: 50% cement, 50% granite dust: 50% lime, 50% cement: 50% lime. The bitumen aggregates and asphalt was subjected to various testing. Test conducted on the bitumen sample are: viscosity test, penetration test, fire and flash point test and specific gravity test. Test conducted on the aggregate were sieve analysis test, specific gravity test, aggregate impact and crushing value test and water absorption test. Test conducted on the asphalt mix was marshal stability test. Results obtained showed that the bitumen samples satisfied the specification given by Federal Ministry of Works and Housing, (1997) as the specific gravity was 1.03, flash and fire point was 287.70C and 316.70C, viscosity was 0.73Ns/m2 and penetration was 69.33mm, the aggregate samples also satisfied the specification given by Federal Ministry of Works and Housing, (1997) as the specific gravity ranged from 2.55-2.76, impact and crushing value was 6.5% and 4.3%, the water absorption of the aggregate was 0.9%, the specific gravity of the aggregate ranged from 2.55-2.76. The optimum binder content was 6%. Assessment of the stability and volumetric properties of asphalt produced with mineral fillers such as 100% granite dust, 100% lime, 100% cement, 50% granite dust: 50% cement, 50% granite dust: 50% lime, 50% cement: 50% lime revealed that the flow ranged from 2.67mm – 3.5mm, void in mineral aggregate ranged from 18.7% - 24.64%, void in total mix ranged from 4.8% - 11.75%, void filled by bitumen ranged from 52.6% - 74.9%, it was observed that the asphalt produced with the different mineral fillers and at different mix combination satisfied the specification given by Federal Ministry of Works and Housing, (1997) for stability, flow and void in mineral aggregate but failed to meet the requirement for void filled by bitumen and void in total mix. The study therefore concluded that Portland cement and granite dust has better effect on stability and volumetric properties of asphalt than hydrated lime.