CCAT alternative building materials testing

From Appropedia
About this project
Keywords building materials, ccat
Authors S Clark
Published 2018-04-27
Completed 2018
Location Arcata, California
Affiliations Campus Center for Appropriate Technology (CCAT)
Humboldt State University
Materials cob, hempcrete
Translation data

Spring Semester 2018 the CCAT Green Building class performed several weathering and strength tests on a set of alternative building materials. The following is the results of those tests.

Materials tests were performed on several masonry and concrete alternative building materials, these included: cob, hempcrete, and papercrete. The recipes for each material are as follows:

Cob[edit | edit source]

  • 1 part clay
  • 1 part sand
  • 1 part straw

Several mixes of cob were used with slight variations in proportion of clay sand and straw, as well as both course and fine sand. The results presented represent an average of multiple mixes.

Hempcrete[edit | edit source]

The hempcrete built in the Spring 2018 class failed to remain structurally sound after curing, so hempcrete from a previous semester was used instead. The recipe for this hempcrete is unknown, but a generic hempcrete recipe is as follows:

Hempcrete binder:

  • 4 parts Hydrated Lime
  • 1 part Portland Cement


  • 4 parts Hemp
  • 1 part Hempcrete Binder