Dissertation Defense: Negasi Niguse Gebremichael

When

Dec. 6, 2022, 8am to 10am

Office/Remote Location

Virtual via Webex

Description

Negasi Niguse Gebremichael, Ph.D. Candidate

Department of Civil and Environmental Engineering

"Effects of Particle Size and Replacement Proportion of Post-consumer Glass"

Committee Members:

  • Dr. Moses Karakouzian, Committee Chair
  • Dr. Pramen Shrestha, Committee Member
  • Dr. Jin Ouk Choi, Committee Member
  • Dr. Vemon Hodge, Committee Member
  • Dr. Alexander Barzilov, Graduate College Representative

Abstract

Concrete is the most used material, next to water, which consumes natural and or manufactured aggregates and energy-intensive cement. Depleting the natural resource due to aggregate extraction and the environmental unfriendliness of cement production have left the construction industry with no choice. Reducing waste, reusing, or recycling can help conserve natural resources. In this regard, the construction industry constantly seeks full or partial replacement of concrete aggregates and cement with recycled material. Glass is a candidate for replacing mineral cement and aggregates in concrete. Partial replacement of major concrete constituents with crushed and ground waste glass may be an effective way to reduce carbon footprint, offset the material cost, and enhance durability.

This research aimed to partially replace concrete cement and fine and coarse aggregate with crushed and ground waste glass material. This study explored the chemical, physical, and mechanical characteristics of crushed waste glass pozzolan and aggregate to compare with mineral pozzolan and aggregates. These characterized glass materials then replaced mineral constituents in varying concrete mix combinations to study the effect on concrete's fresh state, hardened state, and durability properties. The major variables in this research were grain size and replacement proportions of crushed and ground waste glass in concrete. Aggregate gradation (that of NRM aggregates), water/cementitious ratio, ambient temperature (between 76 -78), and slump (3-5 inches) were kept constant.

This study program assessed physical, mechanical, and chemical characteristics of crushed and ground post-consumer glass pozzolan, fine aggregate, and coarse aggregate materials; evaluated fresh state, hardened state, and durability properties of the mix combinations; and compared results among each other, with control mix and against ACI and ASTM specifications. Contrasting with previous research studies that aimed to evaluate the effect of crushed and ground waste glass on concrete as pozzolan or concrete aggregates, this research studies the effect of the particle size and proportion of each particle size in a single mix in a total of 14 combination trial runs. It is found that particle size and replacement proportion of crushed and ground waste glass affect hardened state properties negatively. The lighter weight of the crushed and ground waste aggregate influenced the unit weight of the concrete. It was also found that particle size and replacement proportion affected durability positively.

This research showed that crushed and ground waste glass is viable in partially replacing cement and mineral aggregates in such a way that it satisfies the fresh-state, hardened-state, and durability properties of concrete. Concrete with crushed and ground waste glass showed better durability and met hardened state properties at later ages. Crushed and ground waste glass is not only viable in its effect on concrete properties but also is an environmentally sustainable alternative as it reduces cement production, aggregate dredging, and not to mention landfill.

Price

Free

Admission Information

This event is open to the public. Join via WebEx.

Contact Information

UNLV - Graduate College
Valarie Burke

External Sponsor

Department of Civil and Environmental Engineering