Investigating the Use of Natural Materials for Full Scale Construction
The 2021 Dalhousie Precast Studio continues to explore the natural materials investigation in concrete off-site construction by focusing on the potentials to build full scale and to develop in-depth material experiments. The students worked on investigating the use of biochar in concrete as a fine aggregate for full scale construction. This work was executed and delivered in the summer 2021 remote-learning free lab, and in the design and construction of a full scale demonstrator.
The Precast Studio professors and students believe these technologies have the potential to expand the sustainable technologies of the precast concrete sector by further integrating natural material resources into this sector’s workflow. Potential benefits in this application of biochar are reduction in sand consumption, increased strength at low percentages, and enhanced thermal and hygroscopic properties. Potential impacts of biochar as a sand replacement that need mitigation include reduced compressive strength and permeability at higher percentages, and increased acidity.
Biochar
To date, the Lab personnel at Dalhousie have developed infrastructure for material testing of various concrete recipes. Early investigations revealed that biochar (a by-product of the pyrolysis of biomass) possessed inherent material properties, like low mass, high porosity, intriguing thermal and conductive properties that could be utilized within the construction industry. Biochar is just starting to be understood as a material at a large scale. Stockholm (https://www.hamk.fi/wp-content/uploads/2019/04/Mattias-Gustafsson-pieni.pdf) is using biochar from the country’s garden waste to create biochar to grow trees and plants in public parks. Through the Studio program, the goal is to investigate biochar’s use within a standard concrete mix to identify its role as a carbon sequestering material and general environmental modifier. Overall, the Free Lab investigated the biochar-concrete composite, using compressive strength and permeability data, and explored other design possibilities for the material.
Free Lab – Summer of 2021 As part of the Free Lab at the Deanery Project in Eastern Passage, Nova Scotia, the students began the construction of a ‘Sky Pillar’ in mid-July. The pillar will function as a solar alignment structure, marking solar noon throughout the course of the year. It also will serve as a field-test for a 100 percent biochar fine-aggregate mix. The lab was conducted virtually, but research assistants were able to work on building the structure. Students also had the opportunity to work in the plant with Strescon to experiment with molds and the biochar-concrete composite as well as conduct a virtual plant tour. The Free Lab of 14 graduate and undergraduate students conducted energy simulations of various wall assemblies using biochar-concrete as compared to standard light-weight concrete. These studies demonstrated a range of five to twelve percent energy savings with the modified biochar-concrete mixes.
Unique Program Aspects
Students explored natural materials in concrete off-site construction by focusing on the potentials to build full scale and to develop in-depth material experiments
Virtual plant tour with local precast concrete producer
154 students have participated in the Precast Studio at Dalhousie University since its inception in 2017
Dalhousie University was the first Canadian University to introduce a Precast Studio program as part of their School of Architecture
Program Partners
Dalhousie University
James Forren, Supervisor and Instructor
Kevin Mockford, MITACS Globalink Research Intern
Preston Stronach, MITACS Globalink Research Intern
Strescon Limited