Method To Ensure Stone-on-Stone Contact in Stone Matrix Asphalt Paving Mixtures

Abstract

The use of stone matrix asphalt (SMA) has continued to rise in the United States because of its ability to withstand heavy traffic without rutting. This ability is derived from a stone-on-stone coarse aggregate skeleton. While this coarse aggregate skeleton is imperative for SMA to perform, no quantitative method exists to measure it. A method for determining when stone-on-stone contact exists is presented. The proposed method first determines the voids in the coarse aggregate (VCA) for the coarse aggregate–only fraction of the SMA mixture. Second, the VCA is determined for the entire SMA mixture. When the two VCA values are compared, the VCA of the SMA mixture should be less than or equal to the VCA of the coarse aggregate–only fraction to ensure that stone-on-stone contact exists in the mixture. Five different methods for determining the VCA of the coarse aggregate–only fraction were used to see which performed best and was the most practical. The aggregate degradation produced by each of the five methods was also determined and compared with the coarse aggregate breakdown produced in an SMA mixture compacted with 50 blows of a Marshall hammer. The results indicate that the Superpave gyratory compactor and dry-rodded methods produced the best results. Both methods are recommended for further testing.

Laboratory performance of stone matrix asphalt mixtures with two aggregate gradations

“…Different countries and agencies developed aggregate gradations for SMA mixture. To check the stoneto-stone contact between coarse aggregates, determination of voids in coarse aggregates (VCA) method was suggested by Brown and Mallick [15]. VCA for aggregates in dryrodded condition (VCA DRC ) and also for the entire mixture (VCA MIX ) were calculated using Eqs.…”

Investigation of Coarse Aggregate Strength for Use in Stone Matrix Asphalt

“…In 1997, a study was conducted on ensuring stone-on-stone contact in SMA. Voids in the coarse aggregate (VCA) was found to best represent aggregate packing (14).…”

Rutting analysis of 100 mm diameter polypropylene modified asphalt specimens using gyratory and Marshall compactors

“…When 500 ms load -500 ms rest, 500 ms load -1000 ms rest, 500 ms load -1500 ms rest and 500 ms load -2000 ms rest loading patterns at 50 °C temperature and 500 kPa stress level are analysed respectively, it can be seen that the time of the M-03 type polypropylene fiber reinforced specimens to reach their end of service lives that have been prepared via gyratory compaction are 1.80 times, 1.72 times, 1.01 times and 1.13 times longer than the specimens prepared with Marshall compaction (please refer to Figures 18,20,22 and 24 respectively). To give a more representative figure it can be said that gyratory compaction enhances the polypropylene modified mixtures' end of service life performances approximately 42%.…”

“…The very beneficial effects for the realistic simulation of the compaction on site in the laboratory environment by Superpave gyratory compactors is known and once more can be seen in the studies by various researchers that have been published in the last 13 years [54][55][56][57][58][59][60][61][62][63][64] . In all through these and the similar vast literature about the gyratory compaction studies published till date, limited studies about the 100 mm diameter specimens cored from 150 mm diameter gyratory compacted specimens for the preparation of laboratory prepared specimens have been discussed [19][20][21][22][23][24][25][26] . The vast majority of the other studies is about the physical and mechanical analyses of 150 mm diameter specimens prepared with Superpave gyratory compactors.…”

“…There are various important but "limited" number of studies in the literature that have been published up to date about the utilisation of 100 mm diameter specimens cored from 150 mm diameter gyratory compacted specimens for the preparation of laboratory specimens [19][20][21][22][23][24][25][26] . In all through these studies, the effect of compaction method, that is whether gyratory or Marshall compaction method have been utilised, and the resulting mechanical performance of mixes have been investigated.…”