Laboratory investigation of the properties of asphalt and its mixtures modified with flame retardant

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Date: June 2008
From: Construction and Building Materials(Vol. 22, Issue 6)
Publisher: Elsevier B.V.
Document Type: Article
Length: 3,558 words
Lexile Measure: 1550L

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The purpose of this study was to evaluate the properties of asphalt and its mixtures modified with Decarbomodiphenyl ether (EBPED), Antimony trioxide and zinc borate (ZB). Thermal analysis and Infrared spectroscopy (IR) were used to asses the effects of the flame retardants on physical and chemical properties of asphalt binders. The pavement performances of flame retardant modified asphalt mixture were estimated by Marshall stability, Marshall stability loss, flow value, indirect tensile strength (ITS), ITS loss and dynamic stability. To investigate the flame retardancy of asphalt mixture, the limited oxygen index (LOI) test sample of asphalt mixture was prepared by the substitution of mineral powder for aggregate in mixture. Experimental results indicated that the addition of flame retardant did drastically change the thermal degradation behavior of asphalt binder, but the distribution of functional group and structure of asphalt binders did not appear to alter radically upon flame retardant. Flame retardant modified asphalt mixtures have better flame retardancy and pavement performances. Therefore, flame retardant modified asphalt mixture is a novel road functional material to meet demands as flame retardant materials and road materials at the same time.

Keywords: Asphalt; Flame retardancy; Thermal analysis; Marshall stability; Indirect tensile strength; Limited oxygen index (LOI)

1. Introduction

Asphalt binders with excellent flame retardancy have been prepared successfully by adding various flame retardants such as antimony trioxide, decarbomodiphenyl ether and zinc borate [1]. The introduction of flam retardants into asphalt pavement has the potential to decrease fire accident in tunnels [2-8]. Many research reports and engineering case studies have suggested that the use of stone matrix asphalt (SMA) on road surface can achieve better pavement performances [9,10]. Stone matrix asphalt mixtures are hot asphalt mixtures consisting of high coarse aggregate content, high asphalt content and high filler content, and therefore SMA using flame retardant modified asphalt binders were broadly representative of the asphalt mixture to investigate the flame retardancy and pavement performances. The flame retardancy and pavement performance of asphalt binder containing various flame retardants have been demonstrated in the previous research, but the flame retardant modified asphalt mixture performance is not reported. It is difficult to test the flame retardancy of asphalt mixture by the limited oxygen index (LOI) because large stone grains exist. The sample for LOI test is small in size and coarse aggregate grains exists in asphalt mixture, the misdate of LOI proceeded from the sample became loose and large aggregate grains drop as the sample was ignited.

The main objective of this research study is to evaluate the favourable flame retardancy and pavement performance of flame retardant modified asphalt mixture. To prepare the LOI test sample of the asphalt mixture, the mineral powder was substituted with aggregate in the mixture to evaluate the flame retardancy of the asphalt mixture. Marshall tests, indirect tensile tests and wheel tracking tests were employed to investigate the effect of flame retardants on the pavement performance of asphalt mixture.

2. Experiments

2.1. Raw materials

Asphalt of Superpave performance grade PG76-22 with a penetration of 69 (0.1 mm at...

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Source Citation   

Gale Document Number: GALE|A178712629