Date of Award

Spring 2024

Document Type

Thesis

Publisher

Santa Clara : Santa Clara University, 2024

Department

Civil, Environmental and Sustainable Engineering

First Advisor

Jessica Kuczenski

Second Advisor

Tonya Nilsson

Abstract

Conventional building materials contribute to over 16% of global greenhouse gas emissions annually, therefore, more sustainable materials must be explored. The most readily available material is earth, cob being one of them. Cob is a monolithic earthen material made up of sand, clay, and straw, integrated using water. While this material has been used for thousands of years across the world, it is lacking research, and thus, limiting its implementation into official codes. This project tested six (6) 2’x 2’ cob walls, three (3) six (6) inch thick walls and three (3) twelve (12) inch thick walls using the ASTM E519 standard for diagonal tension testing. The objective of testing was to analyze the shear strength of cob in order to determine its shear capacity during lateral loading. During lateral loading of wind and seismic forces, walls used in rocking shear design are allowed to uplift at the corners and “rock” back and forth. The goal of this report is to show that due to the large mass of cob, walls may resist the uplift from lateral loads while not failing in shear, avoiding the need for steel reinforcement. In addition to testing diagonal compression, this report examines the properties of compression and tensile strength in comparison to other cob research. To better provide awareness on the practicality and benefits of cob, this report presents a design of a cob house and a cost and embodied carbon analysis of the cob structure.

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