Investigation on The Application of A Byproduct of Awash Melkasa Aluminum Sulfate And Sulfuric Acid (AMASSA) As A Blending Material With Fine Deficient Crushed Stone material For Road Sub-Base Construction

Abstract

These days, large amount of wastes are generated due to human activities causing unnecessary expenses and requiring large areas for stockpiling. Awash Melkasa Aluminum sulfate and sulfuric acid factory (AMASSA) located at Awash Melkasa in the Main Ethiopian Rift valley region in Oromia Regional State, generates huge stocks of solid wastes. These solid wastes are stockpiled in the compound of the factory. Recycling of wastes in the construction activities has recently harnessed the researchers’ attention since it reduces the cost of construction and alleviates environmental pollution problems. Therefore, the aim of this study is to investigate the applicability of the byproducts of AMASSA as blending material for fine deficient crushed stone used as a sub-base materials. The engineering properties of the byproduct and the blending of the byproduct with the fine deficient crushed stone were examined under laboratory set ups. ERA adopted AASHTO standard experimental procedures employed to determine particle size distribution, moisture content, specific gravity, Atterberg limit test, maximum dry density, and optimum moisture content, California bearing ratio, organic content, Loss Angeles abrasion test and Flakiness index were investigated. The LL and PI of the byproduct material were respectively 74.9 and 12.9. In addition, the particle size distribution analysis results shows that the byproduct materials of AMASSA passed 100% through the 75 µm sieve openings. According to the AASHTO M145 Soil Classification, the results of the Atterberg limit, LL and PI, as well as the particle size distribution of the byproduct material indicate that the material can be classified as clay group, A-7-5. The CBR of the byproduct was found to be 1.6%, suggesting that the materials cannot be utilized as a sub-grade material as per the ERA Technical Specification. The engineering properties of the fine deficient crushed stone were investigated. Accordingly, the fine deficient crushed stone satisfied the ERA Technical Specification to be used as a sub-base material but the crushed stone did not satisfy the range of the specific limit for particle size distribution. The size distribution of the crushed stone for sieve openings of 10, 2.36, 0.425 and 0.075 mm found to be below the lower limit of the AASHTO T27, indicating that the crushed stone used as sub-base materials in the road construction is deficient in fine particles to meet the ERA Technical Specification. These results suggest the need for blending the crushed stone with fine materials to satisfy the technical requirement. Three different blending percent mass ratios of the byproduct of AMASSA, 3, 6.5 and 10%, were used to improve the crushed stone. Accordingly, 3% blending mass ratio improved the particle size distribution (from not satisfying to full filling the technical specification), CBR (from 83 to 102%), and MDD (2.13 to 2.17 g/cc). Besides, the 6.5% blending ratio also improved the particle size distribution, the CBR (83 to 112%) and MDD (from 2.13 to 2.19 g/cc). However, the 10% mass ratio blending increased the PI of the blend of both the byproduct and the crushed stone. Thus, it this mass percent ratio was not further investigated. The water content, particle size distribution, Atterberg limit, CBR, MDD and OMC of the 3 and 6.5% mass blending ratio results suggest that the blend of the two materials satisfy the AASHTO Technical Specification, avoiding the deficiency in fine materials of the crushed stone that can be used as subbase material for road construction. Based on the findings the study, it is recommended that the AMASSA byproduct can be used as a blending material for fine deficient crushed stone used as a subbase material. However, for practical applicability of the byproduct of the AMASSA, further investigations on the determination of optimum percent mass ratio, reaction of the material with other components of the sub-base materials and field investigation will be required