Document Type

Thesis - Open Access

Award Date

2023

Degree Name

Master of Science (MS)

Department / School

Civil and Environmental Engineering

First Advisor

Rouzbeh Ghabch

Abstract

Lightweight concrete has grown in popularity in the building industry in recent years. Due to its environmental and economic benefits, the construction sector favors using lightweight concrete in applications allowed by the technical specifications. On the other hand, electronics waste (e-waste) is the world’s most rapidly growing waste problem. Given the scale and the volume of global concrete construction, incorporating e-waste as a lightweight concrete construction material can potentially reduce sending electronic waste to landfills, which is an environmental benefit. Additionally, it will help with saving the consumption of virgin aggregates. This study was undertaken to determine the feasibility of using a specific stream of the e-waste obtained from the end-of-life electronic message displays and scoreboards in Portland cement concrete (PCC) to replace natural aggregates while reducing their weight. For this purpose, the collected e-waste was processed by milling and fractionating based on its size (fine and course). Then, a typical concrete mix design using virgin aggregates was developed and was modified into three new mix designs to replace 10%, 20%, and 30% of the mineral aggregates of the virgin mix (by volume) with the milled e-waste while maintaining constant water to cement ration. The effect of incorporating different amounts of e-waste in the PCC samples on their engineering properties, namely workability, air content, unit weight, compressive strength, modulus of rupture, skid resistance (for pavement application), and durability when subjected to the freeze-thaw cycles was determined. The samples were tested to characterize their physical and mechanical properties after curing them in a temperature and humidity-controlled room for 28 days. In addition, another group of the specimens was tested after curing and being subjected to freeze-thaw (F-T) cycles. Furthermore, the evolution of the samples’ skid resistance and material loss was monitored by periodic testing after the completion of every 36 F-T cycles. It was found that the workability of the freshly prepared concrete increased with an increase in the e-waste content. More specifically, the measured slump value of the concrete was found to increase by up to 125% when 30% of e-waste was incorporated in the mixture compared to the mix containing no e-waste. In addition, compressive strength and the modulus of rupture of the PCC were found to decrease steadily when increasing the e-waste content in both cured and conditioned specimens. In addition, the F-T cycles were found to deteriorate all specimens’ compressive strength modulus of rupture, while this effect was more pronounced for those having a higher e-waste content. Furthermore, the skid resistance of the specimens was found to improve with an increase in their e-waste content. The study’s findings showed that the PCC containing high e-waste contents might be considered for non-critical and non-structural applications, which require a relatively lighter and more cost-effective concrete mix compared with those completely prepared by using mineral aggregates. In addition, the findings of this study may help with protecting the environment by reducing the e-waste ending up in landfills.

Library of Congress Subject Headings

Aggregates (Building materials)
Electronic waste.
Portland cement -- Additives.
Concrete -- Additives.

Publisher

South Dakota State University

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Rights Statement

In Copyright