Search results for "Gyratory compactor"
showing 4 items of 4 documents
Analytical approach for the mix design optimisation of bituminous mixtures with crumb rubber
2018
The present paper provides a basis for defining a mix design method specifically tailored to rubberised asphalt that takes into account the behaviour of crumb rubber. An analytical approach to quantifying the recovered deformation of crumb rubber in the post-compaction phase has been developed in order to adjust the number of gyrations proposed by the Superpave method for compacting specimens of hot mix asphalt using a Superpave gyratory compactor. The maximum allowable amount of rubber has been calculated. Finally, a step-by-step protocol has been proposed in order to fabricate and compact crumb rubber modified mixtures with the gyratory compactor.
Increased Stability of Rubber-Modified Asphalt Mixtures to Swelling, Expansion and Rebound Effect during Post-Compaction
2017
The application of bituminous mixtures modified with rubber from scrap-tires require attention and care during mixing and compaction. Rubber modifies the properties because it reacts in the internal structure of bitumen at high temperatures changing the performance of the mixture (interaction process of solvents with binder-rubber aggregate). The main change is the increasing of the viscosity and elasticity of the binder due to the larger sizes of the rubber particles by dry process but, this positive effect is counteracted by short mixing times, compared to wet technology, and due to the transport processes, curing time and post-compaction of the mixtures. Therefore, negative effects as sw…
Fundamental characterisation of reclaimed asphalts: The importance of testing homogeneous specimens
2013
This study highlights the importance of defining appropriate specimen manufacturing procedures when assessing the fundamental properties of reclaimed asphalt (RA) mixes for further modelling purposes. Two gyratory compactor procedures were used: the first leading to specimens with a non-uniform air voids distribution and the second tailored to obtain homogeneous specimens. The study was performed by using three stone mastic asphalts incorporating up to 30% of RA but designed to have identical properties. A detailed characterisation of the loose mixes and binders, an X-ray computer tomography micro-structural study of the manufactured specimens and a further mechanical characterisation showe…
Reclaimed asphalt test specimen preparation assisted by image analysis
2015
This paper presents a laboratory investigation aimed at establishing a protocol for the production of homogeneous asphalt mixtures test specimens, incorporating reclaimed asphalt by using a gyratory compactor with coring and trimming works. Stone mastic asphalt specimens were compacted at the previously identified target densities with the final aim of obtaining specimens with a fixed and homogeneous air void distribution. A microstructural study was conducted to characterize the homogeneity in the air void distribution using X-ray computed tomography (CT) combined with image analysis techniques. The study concluded that the gyratory compactor is suitable for producing homogeneous test spec…