Disruption of air voids continuity based on permeability loss due to mortar creep. (30th July 2016)

• Record Type: Journal Article
• Authors: Mohd Hasan, Mohd Rosli; Hamzah, Meor Othman; van de Ven, Martin; Voskuilen, Jan
• Is Part Of: Construction & building materials. Volume 116(2016)
• Page Start: 347
• Page End: 354
• Publication Date: 2016-07-30
• Subjects: Porous asphalt -- Mortar creep -- Air voids continuity -- Drainage capability -- Permeability loss; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2016.04.121
• Languages: English
• ISSNs: 0950-0618

Abstract

Graphical abstract: All factors significantly affect the occurrence of mortar creep in porous asphalt prepared in the laboratory, especially for the specimens conditioned at the highest temperature. Permeability loss was more significant on the specimens prepared using conventional binder at a higher bitumen content. Highlights: Mortar creep takes place due to the downward migration of asphalt mortar. Effects of gradations, binder types, binder contents, and temperatures were studied. Assessment was continuously monitored using a simple falling head permeameter. Mortar creep has significantly disrupted the continuity of air voids in the samples. Samples prepared using conventional bitumen at high binder content undergoes greater permeability loss. Abstract: Mortar creep takes place when the asphalt mortar continuously migrates downwards due to gravitational forces and can significantly disrupt air voids continuity in porous asphalt samples. This study was an extension to a previous work that ascertained the existence of the binder creep phenomenon as reflected from the continual permeability loss especially on samples conditioned at elevated temperatures. Nonetheless, in this paper, the terminology "mortar creep" was adopted instead of "binder creep". This is because, in an asphalt mixture, the aggregates are glued together not by the binder in isolation, but by the mortar; which is comprised of asphalt binder, fine aggregates and filler. The variables investigated included aggregate gradation, binder type, bitumen content and conditioning temperature. The mixes were prepared using conventional bitumen (60/70 pen. grade) and modified asphalt binder (PG76) at three levels of binder content at 0.5% increment. Permeability loss was continuously monitored over an extended period up to 120 days using a simple falling head water permeameter. Over the test period, the samples were separately conditioned at 15 °C, 20 °C, 30 °C and 35 °C. The results showed that all factors significantly affect the occurrence of mortar creep in porous asphalt prepared in the laboratory, especially for the specimens conditioned at the highest temperature. Permeability loss was more significant on specimens' prepared using conventional binder at a higher bitumen content.