Introduction
Non-destructive tests (NDTs) are a type of experimental method useful in determining the quality of structures. They can be utilized to analyze multiple different aspects of a building such as energy efficiency, strength, flaws, and damage. NDTs are valuable because they can help to
assess and monitor the health of existing structures without altering any physical qualities.
The First Peoples House
The University of Victoria First Peoples House is an
academic building on campus for Indigenous students. It was constructed in 2008 and is a LEED ® Gold building
[1]. The building has 2 rammed earth walls on its east and west face.
Objective
To determine performance of both rammed earth walls at the First Peoples House after 11 years of exposure. Non- destructive tests are used and results are compared to data from previous studies from the 7 year and 9 year mark after construction [1],[3].
References
1. K. Allen and R. Gupta, “Current State of Modern Rammed Construction: A Case Study
of First Peoples House after Seven Years Exposure,” in “Key Engineering Materials,” Dept. Mech. Eng., Univ. Victoria, 2016.
2. Rammed Earth Constructions. Information About Rammed Earth [Online]. Available:
http://www.rammedearthconstructions.com.au/rammed-earth-info/
3. G. Kutturu, “Boundary effects and material behaviour of Rammed Earth Construction,”
M.S. thesis, Dept. Mech. Eng., Univ. Victoria, Victoria, 2017.
Results
• Quality of the interior wall face is higher than the exterior wall face
• Increased compressive strength on interior
• Heat loss is greater on the east wall than the west wall • Temperature change is larger on east wall
• Quality of the east wall is greater than the west wall • Increased average velocity on east wall
• West wall may contain more flaws than the east wall
• Impact echo graphs from the west wall show
more peaks
Limitations
• Testing was completed on two different days, which could alter results due to changes in weather
• Assumptions are made regarding the wall U-Value and emissivity in order to calculate heat transfer through walls, actual values may vary
• Background noise affected acoustic testing results
• Some test values had large deviations, a higher accuracy in results can be achieved through further testing
Innovative Non-Destructive Techniques for
Assessing Quality of Building Envelopes
Lois Tso
Rammed Earth Walls
Rammed earth walls are composed mainly of compacted soil and aggregates. It is a green and sustainable
construction material. Benefits include [2]
• Reduced CO2 emissions and waste produced
• High thermal mass
• High fire resistance
• Low embodied energy
• Natural aesthetics
Non-Destructive Tests
Use 7 measurement locations on the walls for testing
2. Infrared Camera
Surface temperature of the walls is determined with the camera. Using the wall U-Value and change in surface
temperatures, calculations are completed to determine heat transfer through walls by conduction.
3. Ultrasonic Pulse Velocity
An indirect energy pulse is sent and received through the walls. Pulse distance and travel time collected are then
converted to velocity. With this, the quality of walls can be found.
4. Impact Echo
Locates flaws within the walls. A hammer is used to strike the wall surface. Sounds are recorded and analyzed in
frequency and amplitude
.
1. Rebound Hammer
Determines compressive strength of walls. Impact energy is sent into the wall and a rebound energy is returned to the device. The energy is then correlated to wall strength.
0 5 10 15 20 25 30 1 2 3 4 Te m pe ra tur e, C
Points Along Wall
Surface Temperature of East Wall
Inside Temperature Outside Temperature Temperature Difference
0 10 20 30 40 50 60 1 2 3 4 Co m pr es siv e S tr eng th ( MP a)
Points Along Wall
East Wall Strength
Inside Surface 2019 Outer Surface 2019
0 10 20 30 40 50 60 1 2 3 Co m pr es siv e S tr eng th ( MP a)
Points Along Wall
West Wall Strength
Inside Surface 2019 Outer Surface 2019
Acknowledgements
I would like to thank my supervisor Dr. Rishi Gupta for this research opportunity, the staff at the First Peoples House for their help, as well as my friends Sydney Friesen and Boyu Wang for their assistance in testing
March 6, 2019
Supervised by Dr. Rishi Gupta, Department of Civil Engineering
Research supported by the Jamie Cassels Undergraduate Research Awards
From comparison of rebound hammer and infrared imaging data from 2 years ago and 4 years ago [1],[3]
• Compressive strength increased for west wall • Compressive strength results vary for east wall • Heat loss increased on average
Average Heat Loss Per Room (W/m2K)
E. Wall Room 1 W. Wall Room 1 W. Wall Room 2
2015 4.46 4.81 3.56 2017 4.31 - - 2019 5.12 4.27 4.08 0 5 10 15 20 25 1 2 3 Te m pe ra tur e, C
Points Along Wall
Surface Temperature of West Wall
Inside Temperature Outside Temperature Temperature Difference
0 10 20 30 40 50 60 1 2 3 Co m pr es siv e S tr eng th ( MP a)
Points Along Wall
Compressive Strength of West Wall
Inside Surface 2019 Outside Surface 2019 Outside Surface 2017 Inside Surface 2015 Outside Surface 2015
0 10 20 30 40 50 60 1 2 3 4 Co m pr es siv e S tr eng th ( MP a)
Points Along Wall
Compressive Strength of East Wall
Inside Surface 2015 Inside Surface 2017 Inside Surface 2019 Outside Surface 2015 Outside Surface 2017 Outside Surface 2019 0 500 1000 1500 2000 2500 3000 3500 4000 4500 1 2 3 Vel oci ty (m /s )
Points Along Wall
UPV Velocity of West Wall
UPV Velocity Outside
0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 1 2 3 4 Vel oci ty (m /s )
Points Along Wall
UPV Velocity of East Wall
