Investigation of the Use of Recycled Concrete Aggregates in Porous Asphalt Mixture

Graduation Year

2024

Document Type

Dissertation

Degree

Ph.D.

Degree Name

Doctor of Philosophy (Ph.D.)

Degree Granting Department

Civil and Environmental Engineering

Major Professor

Qing Lu, Ph.D.

Committee Member

Mahmood Nachabe, Ph.D.

Committee Member

Andres E. Tejada-Martinez, Ph.D.

Committee Member

Rasim Guldiken, Ph.D.

Committee Member

Lu Lu, Ph.D.

Keywords

Class C fly ash, Clogging rehabilitation, Construction and demolition waste, Moisture susceptibility, Recycled concrete aggregates, Sound absorption

Abstract

This study aims to address the national need for using recycled concrete in road pavements. This is especially important in the governmental and corporate sectors, where reducing the cost and carbon footprint of construction projects is a priority. The long-term goal is to meet the public demand for environmentally friendly infrastructure and minimize the harmful effects of waste disposal on humans and the environment.

The project focuses on using recycled concrete aggregate (RCA) in porous asphalt pavement to reduce stormwater runoff, a popular environmentally friendly road design. However, compared to regular dense asphalt mixtures, porous asphalt mixtures (PAM) are more vulnerable to climate impact and traffic loading. Aging and excessive moisture deteriorate the asphalt binder, causing adhesive loss at the binder-aggregate interface. Recent research has shown that the stability of PAM is greatly influenced by the type of materials used.

The general approach involves conducting laboratory tests and statistical models to assess materials and identify variables that determine PAM's mechanical, durability, and clogging characteristics. The central hypothesis is that incorporating RCA into asphalt pavement does not necessarily reduce its performance. To test this, eight mix designs containing RCA were compared to PAM made with natural aggregate to determine their suitability for PAM. This evaluation considered five main mix design criteria: stability, permeability, moisture susceptibility, sound absorption, and abrasion resistance. The specific objectives of the study are to evaluate the suitability of RCA in PAM and identify the variables that influence its mechanical, durability, and clogging characteristics.

Based on the study, it has been found that RCA has the potential to enhance PAM's Marshall stability, indirect tensile strength, stiffness, and raveling resistance, to levels comparable to mixtures with natural aggregates. These findings are expected to have a significant impact on the field of construction and demolition by reducing the amount of waste sent to landfills, conserving natural resources, and reducing overall project costs.

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