ORCID Identifier(s)

0000-0002-0352-231X

Graduation Semester and Year

Fall 2024

Language

English

Document Type

Thesis

Degree Name

Master of Science in Civil Engineering

Department

Civil Engineering

First Advisor

Dr. MD Sahadat Hossain

Second Advisor

Dr. Xinbao Yu

Third Advisor

Dr. Laureano Hoyos

Abstract

Recycled Crushed Concrete Aggregate (RCCA) offers a sustainable alternative to natural aggregate in construction, reducing reliance on natural resources and diverting construction and demolition debris from landfills. Similarly, the escalating global plastic waste crisis highlights the need for innovative solutions to address non-biodegradable waste disposal challenges and create opportunities for recycling plastics into value-added applications. This study explores the potential of RCCA mixed with plastic waste, such as HDPE and PP, as a viable substitute for natural aggregates in flexible pavement base layers, with a focus on hydraulic properties and drainage performance to enhance pavement durability.

A comprehensive experimental program was conducted to evaluate key parameters, including particle size distribution, moisture-density relationship, specific gravity, and hydraulic conductivity. AASHTO Pavement ME Design tool DRIP (Drainage Requirement in Pavement) was employed to analyze drainage time and required layer thickness for various RCCA-plastic mix combinations. Results indicated that permeability of RCCA-plastic mix samples, with 3% and 5% RCCA replaced by HDPE and PP, was higher than that of 100% RCCA samples at cement dosages of 4%, 6%, and 8%. However, increased cement content negatively impacted permeability, with better results obtained at 4% and 6% cement dosages.

DRIP analysis revealed that higher hydraulic conductivity materials required less drainage time and reduced depth of flow or base thickness. A threefold increase in hydraulic conductivity was achieved by replacing 3% RCCA with HDPE at 4% cement, reducing drainage time by 70.7%. Strong correlations were established between hydraulic conductivity and drainage time (R² = 0.83–0.87). Materials with greater hydraulic conductivity were classified as better-quality drainage materials as well. The drainage quality of RCCA was improved from “Poor” to “Fair” when 3% and 5% RCCA was replaced with recycled plastic across all cement dosages. Improved drainage quality of the materials resulted in improved estimated drainage coefficient for the two cases considered in this study. In practice, replacement of RCCA by 3% or 5% plastic can potentially reduce the design base thickness because of their improved drainage coefficient.

Keywords

Recycled Crushed Concrete Aggregate (RCCA), Pavement base, Hydraulic conductivity, Drainage, DRIP.

Disciplines

Civil Engineering | Geotechnical Engineering | Other Civil and Environmental Engineering | Transportation Engineering

Available for download on Tuesday, December 16, 2025

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