Laboratory Evaluation of the Use of Florida Washed Shell in Open-Graded Asphalt Mixtures.

Mohammad Alharthai,Ahmed Elnihum,Asad Elmagarhe,Qing Lu

doi:10.3390/ma14227060

Mohammad Alharthai, Ahmed Elnihum + Show 2 more

Open Access

https://doi.org/10.3390/ma14227060

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Journal: Materials	Publication Date: Nov 21, 2021
Citations: 3	License type: CC BY 4.0

Affiliation: University of South Florida, Najran University

Abstract

This study investigates the substitution of conventional aggregate with a Florida washed shell in open-graded asphalt mixtures and evaluates the optimal substitution percentage in aggregate gradations of various nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm). Laboratory experiments were performed on open-graded asphalt mixture specimens with the coarse aggregate of sizes between 2.36 and 12.5 mm being replaced by the Florida washed shell at various percentages (0, 15, 30, 45, and 100%). Specimen properties relevant to the performance of open-graded asphalt mixtures in the field were tested, evaluated, and compared. Specifically, a Marshall stability test, Cantabro test, indirect tensile strength test, air void content test, and permeability test were conducted to evaluate the strength, resistance to raveling, cracking resistance, void content, and permeability of open-graded asphalt mixtures. The results show that there is no significant difference in the Marshall stability and indirect tensile strength when the coarse aggregates are replaced with Florida washed shell. This study also found that the optimum percentages of Florida washed shell in open-graded asphalt mixture were 15, 30, and 45% for 12.5, 9.5, and 4.75 mm NMAS gradations, respectively.

Highlights

Open-graded asphalt mixture has been used by many road agencies in the UnitedStates since 1950 [1]
This study investigated and evaluated the use of Florida washed shell in open-graded asphalt mixtures through laboratory experiments on mixture performance
Three aggregate open gradations of different nominal maximum aggregate sizes (NMASs) (i.e., 4.75, 9.5, and 12.5 mm), one Superpave performance-graded asphalt binder (PG 76-22), and granite aggregates were included in the study to prepare the asphalt mixture specimens

Summary

Introduction

States since 1950 [1] It features a large, interconnected air void system in the compacted mixture, which is achieved through the use of an open aggregate gradation. When the open-graded asphalt mixture is used in a porous pavement structure, it allows water to infiltrate into the base and subgrade layers to reduce storm water runoff and remove some contaminants from the runoff. Aggregate (as the structural skeleton of the mixture) and asphalt binder (as glue for the aggregate) are the two major components of an open-graded or porous asphalt mixture. Based on previous studies [3,4,5,6], the gradation and nominal maximum aggregate size (NMAS) of aggregates have a significant effect on the durability and permeability of asphalt pavement surface. NMAS is the largest sieve size that retains some of the aggregate particles but generally less than 10 percent by weight [7]

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Results

Conclusion