Adobe brick (or Mudbrick) is commonly used as a construction material for residential structures in the Southwest portion of the United States. Adobe bricks are formed from mud that is composed of sand, silt, clay and water that is further mixed with straw then allowed to dry in the open environment. The straw aids in providing reinforcement for the brick and helping the brick dry more evenly which in turn reduces the amount of shrinkage cracks. The final product is a strong, durable, heavy brick used in the construction of homes. While this practice of adobe brick construction has been around for centuries there is still a lot of unknowns regarding the mechanical properties of the bricks particularly at different material compositions, reinforcement levels and moisture contents. This research investigates the material properties of adobe through traditional material and structural testing and through the use of digital image correlation to measure surface strains of the test specimens. Three types of testing were completed: material tests measuring the compressive strength of brick prisms, material tests measuring the bending strength of small modulus of rupture specimens, and structural tests measuring the in-plane lateral load capacity of one quarter scale walls. In 3-D DIC, the measured object is photographed with a pair of digital cameras before, during and after a load event, and a stochastic pattern marked on the object is tracked from one set of images to the next such that a full field of displacements is derived. Major findings were:
- DIC was a valuable tool for measuring displacements and strains in adobe materials and structures.
- DIC was able to allow visualization of adobe material failure modes and failure progression.
- Fibers within adobe bricks allowed the material to reach large deformations prior to complete collapse.
- This was the first study to use DIC on multiple faces of compression specimens to measure deformations in order to determine Modulus of Elasticity (E).
- The value for Modulus of Elasticity for the adobe used in this project was between 39,000 and 51,000 psi, depending on the method of calculation.
This material is based upon work supported in part by the National Science Foundation (NSF) under NSF Cooperative Agreement Number EEC-1449501. Any opinions, findings and conclusions, or recommendations expressed in this material are those of the author(s), and do not necessarily reflect those of the NSF.
Date of publication
Dr.Michael McGinnis, Dr. Michael Gangone, Dr. Gokhan Saygili
Wasti, Ashmita, "Experimental Investigation of Adobe Structures with Digital Image Correlation" (2019). Civil Engineering Theses. Paper 14.