Abstract
Stone Matrix Asphalt Concrete (SMAC) is known as tough, stable, rut-resistant mixture. In this investigation, SMAC was prepared in the laboratory using gap graded aggregates, asphalt cement, mineral filler and coal fly ash as stabilizing agent. Specimens were prepared using static compaction to the target density based on asphalt content for each case. The prepared Specimens were subjected to the 1200 repeated compressive stresses at 25 ºC under various stress levels using the pneumatic repeated load system PRLS. Specimens were subjected to microcrack healing process by external heating for 120 minutes at 60 °C, then it practices another cycle of repeated compressive stresses. The resilient modulus, permanent deformation, and rutting resistance under three levels of stress have been assessed. It was concluded that the resilient modulus Mr increases by (66, 50 and 31) %, (36, 50 and 31) % and (62, 37 and 69) %, while the permanent deformation decreases by (25, 11.4 and 25) %, (19, 31.6 and 14.5) % and (14, 9 and 8.3) % after implementation of fly ash at (OAC-0.5, OAC and OAC+0.5) % binder content under (0.068, 0.138 and 0.206) MPa of repeated compressive stress respectively. The resilient modulus increased by (17.6, 15.3, 10.5) % , (42.8, 51, 37.5) % and (18.7, 25, 23.6) % and the permanent deformation decline by (3.52, 31.66, 6.25) % under repeated compressive stresses of (0.068, 0.138, 0.206) MPa at (25 °C) after healing for mix with (4.6, 5.1, 5.6) % asphalt content respectively when compared with mixtures before healing.
Highlights
The stone matrix asphalt (SMA) design concept relies on stone-on-stone contact to provide strength and a rich mortar binder to provide durability
The test results of Stone Matrix Asphalt Mixture at 0.206 MPa show that the Mr decreased by (36.36 and 26.31) % when the asphalt content increased and decreased by 0.5 % from OAC respectively
The higher Mr could be achieved at 0.068 MPa stress level and at OAC, this may be attributed to the requirement of asphalt which must be enough to bind the aggregates under the low traffic loading
Summary
The SMA design concept relies on stone-on-stone contact to provide strength and a rich mortar binder to provide durability. These objectives are usually achieved with a gap-graded aggregate coupled with fiber and/or polymermodified, high asphalt content matrix, [1]. Ghasemia and Marandi, [2] evaluated the advantages of adding styrene butadiene styrene (SBS) polymer to the base bitumen with the penetration grade of 60/70 and to modify stone matrix asphalt (SMA) in flexible pavement. Asphalt mixture performance tests including indirect tensile strength and resilient modulus were performed on the modified and control asphalt samples. It was concluded that SMA could be successfully designed to have stone-on-stone contact
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