Investigation of Stone Matrix Asphalt Mortars

Abstract

The use of stone matrix asphalt (SMA) has continued to increase in the United States since its initial application in 1991. This preference for SMA has been linked to its ability to withstand heavy traffic without rutting. The antirutting capability of SMA is normally accredited to the presence of a stone-on-stone aggregate skeleton in the mixture. However, the mortar in an SMA mixture is also important. The mortar is composed of fine aggregate, filler, asphalt cement, and a stabilizing additive. Work to characterize SMA mortars is detailed. For testing purposes, the mortar was broken into separate phases, total mortar and fine mortar. The fine mortar was tested using the Superior Performing Asphalt Pavements system (Superpave) binder tests. The total mortar was tested using the bending beam rheometer, resilient modulus, indirect tensile test, and Brookfield vis-cometer. The results indicate that the fine and total mortars are closely related. In addition, it was determined that at least some of the Superpave tests can be used to characterize SMA mortars. It is recommended that further testing be completed and specification criteria be established for the mortar.

Effect of Coal Combustion Products on high temperature performance of asphalt mastics

“…Previous studies reported on the significance and applicability of the Superpave Ò protocols and equipment such as the Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) for the investigation of mastics and fine mortars [3,10]. Following these recommendations, the rheological properties were investigated by Dynamic Shear Rheometer (DSR) using 25 mm samples at three different temperatures 52°C, 58°C and 64°C for PG58-28 and 58°C, 64°C and 70°C for PG64-28.…”

“…An increase in Al 2 O 3 , SiO 2 , SAF (combined SiO 2 , Al 2 O 3 , and Fe 2 O 3 ) and D 10 results in a decrease in the stiffening rate for both types of binders which can be an indication of plasticizing (softening). On the other hand, higher CaO, SO 3 and LOI values result in an increase in the stiffening rate, which identifies stiffer mastics. The highlighted values in Tables 7 and 8 reflect the statistically significant factors influencing the stiffening rate of mastics.…”

“…Each year, 4000 asphalt plants in the U.S. produce 500 to 550 million tons of asphalt pavement material worth in excess of $30 billion [1][2][3][4][5][6][7]. Increased traffic demands and factors such as escalating price of crude oil and rising energy costs, all contribute to increased production costs of asphaltic concrete.…”

“…The modification of the asphalt is commonly achieved through blending asphalt with synthetic products; such as polymers. The use of fly ash to enhance the performance of asphalt concrete was demonstrated; however, in spite of potential benefit, has not been adopted on a commercial scale [1][2][3][4][5][8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24]. The use of Class C ash has received most of the research focus.…”

Characterization of Asphalt Materials Using X-Ray High-Resolution Computed Tomography Imaging Techniques

“…The better performance of Stone Matrix Asphalt (SMA) is attributed to better coarse aggregate skeleton in these mixes compared to the dense graded HMA (Brown et al 1998;Scherocman 1991). The Bailey method of gradation selection (Vavrik et al 2001) reportedly produces an aggregate blend that is packed together in a systematic manner, to form an aggregate skeleton with the required interlock and packing.…”