Evaluation of Saw Dust Ash as Mineral Filler in Asphalt Mixture

The quest for economy in asphalt production using locally available materials necessitated this research which is aimed at evaluating the suitability of Saw Dust Ash (SDA) as mineral filler in asphalt mixture.Chemical analysis, sieve analysis, specific gravity and plasticity index tests were performed on SDA. Asphalt briquettes prepared using Ordinary Portland Cement (OPC) without saw dust as filler serve as the control. SDA was used to replace the Portland cement at 0% to 100% at an interval of 10% by weight. Marshall Test was conducted on all briquettes produced with SDA and OPC. Results of tests show that increase in SDA resulted in reduction in the value of bulk density. It was also observed that the total voids in the mix increased with SDA content, while the values of stability and flow decreased with SDA. The optimum bitumen content of 6.0% was used to prepare specimens. The flow value of asphalt decreased from 2.0mm when only the cement was used as filler to 1.0mm when the cement was completely replaced with 100% SDA. Voids in mineral aggregate increased from 18.28% when 100 % cement was used as filler to 26.32% when cement was completely replaced with SDA. Based on results of tests, the use of cement partially replaced with 10% SDA at 6% bitumen content is recommended for use in asphalt production.

 

 

Continuous generation of wastes arising from industrial by-products and agricultural residue, create acute environmental problems both in terms of their treatment and disposal. The construction industry has been identified as one of the areas where the waste can be absorbed, with the majority of such materials used as filler in concrete (Antihos et al., 2005). If these fillers have pozzolanic properties, they impart technical advantages to the resulting concrete and also enable larger quantities of cement replacement to be achieved (Hossain, 2003). Approximate utilization of these materials brings ecological and economic benefits. Waste material recycling into useful products has been the current method of solving waste problems (Ahmed, 2006). Material recycling has been a common practice for most of human history with record as far back as Plato in 400 BC (Grosse, 2010). Recycling is a process to change waste materials into new products to prevent hazards associated with waste, reduces the consumption of fresh raw materials, and it also reduces greenhouse gas emissions arising from the conventional method of disposing such wastes (Grosse, 2010).