Evaluate the Effect of Waste Ground Rubber Tire Powder in Hot Mix Asphalt
In the present study, the effect of waste ground rubber tire powder (WGRTP) modifier on various mechanical properties such as Marshall stability, flow, Marshall quotient (MQ), bulk specific gravity, air voids, voids filled with bitumen (VFB) and percent voids in compacted mineral aggregates (VMA) of asphalt mixture has been evaluated. The Marshall tests of the polymer modified asphalt mixture, prepared through dry process, indicated the optimum waste polymer modifier content to be 5% by weight of mix. The waste polymer modified asphalt mix containing 5% WGRTP showed considerable improvement in various mechanical properties of the mix compared to the conventional asphalt mixture. The appropriate amount of the added WGRTP was found to be 5% by weight of aggregate. This percentage results in the maximum level of stability. Keywords—Hot mix asphalt; Waste ground rubber tire powder; Dry process; Marshall test method
Flexible Pavement: A Review on the Influence of Waste Rubber Particles in Asphalt and Asphalt Mixtures
Asphalt and aggregates are used in the flexible pavement to form asphalt concrete as the surface and binder courses. Both materials are essential components of hot mix asphalt (HMA). The asphalt concrete might not fully have the potential to endure heavy traffic loading, high temperature, and intensive rainfall, especially in tropical regions because of its stiffness, which often developed in fatigue cracking and permanent deformation in road pavement. The number of failures caused by those factors reduces the durability of pavement performance. Until now, the research about newly selected modifiers and techniques to modify asphalt and asphalt mixtures is essential. Using waste rubber particles in asphalt and asphalt mixtures to improve their characteristics has become a technique of great potential for many years round. The modifier makes asphalt and asphalt mixtures more resistant to temperature variations and high traffic loads and reduces the maintenance costs, and improves the riding surface of the pavement as was reviewed. This paper reviews the influence of waste rubber particles in asphalt and asphalt mixtures with particular reference to the dry and wet processes considering design mixes. The primary focus of the review was studied, which highlights some critical issues considering its design mixes (dry and wet processes), testing method, and performance on road pavements. Recommendations called for additional research for performance improvement of waste rubber particles in asphalt and asphalt mixtures.
Mechanical behaviour and durability of high volume fly ash cementitious composites
The purpose of this research is to separate different morphological particles of ASTM class F fly ash, and study their effect on mechanical behaviour and durability of high volume cementitious mixtures. In this research wet separation of raw fly ash is carried out, which resulted in three layers of different morphological particles. The first layer of particles float, comprise of about 1-5% of fly ash, is identified as cenospheres or hollow spheres. The second layer of particles is measured to be 55-60% of raw fly ash and consisting of porous spherical and rounded particles rich in Si and Al. The third layer particles is measured to be about 35-40% of raw fly ash. High volume fly ash cementitious composites containing second or third layer particles are tested under compression and bending, highlighting a higher strength and ductility in comparison to cementitious ones containing raw fly ash particles. KEYWORDS. Cementitious matrix; Raw fly ash; Second layer particles; Third layer particles.