Laboratory performance of stone matrix asphalt mixtures with two aggregate gradations

Abstract

Stone matrix asphalt (SMA) is a gap-graded bituminous mixture which can be used in surface layer of high volume pavements. The mixture has higher concentrations of coarse aggregates, providing strength and rut resistance to the mixture, and higher asphalt content giving durability. There must be a proper stone-to-stone contact between the coarse aggregates of SMA, and hence aggregate gradation is an important factor in this mixture. In the current study, two aggregate gradations, with nominal maximum aggregate sizes (NMAS) 16 and 13 mm were adopted to prepare SMA mixtures and their laboratory performances were compared. Polymer-modified bitumen (PMB) was used as the binder material and no stabilising additive was used, since drain down was within permissible limits for both mixtures with PMB. Conventional cylindrical specimens were prepared in superpave gyratory compactor with bitumen contents 5.0 %, 5.5 %, 6.0 %, 6.5 % and 7.0 % by weight of aggregates, and volumetric and Marshall properties were determined. Tensile strength, behaviour to repeated loading etc. were checked for cylindrical specimens prepared at optimum bitumen content, whereas specially prepared slab specimens were used to check the rutting resistance of SMA mixtures. From the laboratory study, it was observed that, out of the two SMA mixtures, the one with NMAS 16 mm performed better compared to the other. These improved properties may be attributed towards the larger coarse aggregate sizes in the mixture.

Wear Analysis of a Heterogeneous Annular Cylinder

“…To improve the quality and durability of the contact between road and tire, knowledge about the time-dependent behavior of the contact is vital. In the last few decades, many tests have been carried out to study the tire-road interaction, e.g., by changes in the structure of aggregates and asphalt binders [2], and the addition of additives [3]. Recent research [4,5] covers an experimental approach to this contact problem to determine the long-term behavior of different construction materials being exposed to the polishing effects of the tires of vehicles.…”

Recycled stone mastic asphalt mixtures incorporating high rates of waste materials

“…Since the recycled SMA mixtures do not present binder drainage problems, they were tested to assess their water sensitivity. According to Sarang et al [26] SMA mixtures should exhibit a minimum tensile strength ratio (TSR) of 80%, but NAPA [27] mentioned a minimum value of 70%. In Figure 10, it is possible to observe that all the recycled asphalt mixtures show TSR values above the minimum recommended value (80% -represented in the graph by the grey line).…”

Cost-benefit Analysis of RAP Incorporated Stone Matrix Asphalt Mixtures

“…The main objective of the study is to evaluate the influence of RAP content and rejuvenator dosage on the cost-benefit ratio of the Stone Matrix Asphalt mixtures (SMA). SMA is a gap graded pavement which consists 70% of coarse aggregate which forms an aggregate skeleton and a fair amount of fine aggregate helps to fill the voids present in the coarse aggregate and give better stone-on-stone contact and gives strength to the mixture [10,11].…”