Thesis Defence: Evaluation of the Effect of Pulp Mill Fly Ash – Hydrated Lime Mixture on the Thermomechanical Properties of Modern Rammed Earth: A Comparison with Conventional Cement Stabilizer

Sarbesh Sharma Adhikari, supervised by Dr. Sumi Siddiqua, will defend their thesis titled “Evaluation of the Effect of Pulp Mill Fly Ash – Hydrated Lime Mixture on the Thermomechanical Properties of Modern Rammed Earth: A Comparison with Conventional Cement Stabilizer” in partial fulfillment of the requirements for the degree of Master of Applied Science in Civil Engineering.

An abstract for Sarbesh Sharma Adhikari’s thesis is included below.

Defences are open to all members of the campus community as well as the general public. Registration is not required for in person defences.

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ABSTRACT

The ever-rising demands for housing and the carbon footprints associated with construction materials have increased the relevance of sustainable construction practices that use natural, low-carbon building materials. In this regard, Rammed Earth (RE) is a construction technology with eco-friendliness, low embodied carbon, and naturally available raw materials. Although this technique has been in practice for centuries, it is still not widely approved as a standard method due to misconceptions regarding its strength, structural design, and lack of building codes. To meet the current standard of construction practices, builders use up to 20% Portland Cement (PC); however, this does not contribute to reducing carbon footprints. This study aims to enhance the sustainability of stabilized RE by replacing energy-intensive PC with eco-friendly alternatives. It also investigates the effects of binder materials such as pulp mill fly ash (PFA), a locally available waste material and hydrated lime (HL), on modern rammed earth’s mechanical and thermal attributes. The two optimum RE mix designs with 5% and 10% PC treated with HL and PFA achieved up to 85% and 200% improvement in compressive strength, respectively, compared to the control specimen with 10% PC. A multicriteria analysis— using the mechanical properties along with the supplementary results of freeze-thaw durability, thermal conductivity, and preliminary life cycle impact assessment (LCIA) of treated RE specimens—showed the significance of PFA and HL as alternative additives in reducing the cement content and enhancing the strength of RE, making the modified RE suitable for cold regions with extremely low winter temperature. Moreover, this study contributes to the wider acceptance of RE as a low carbon material in green building construction, because of its strength, durability, and sustainability.