Project data
Authors Solomon Clark
Location Arcata, California
Completed 2018
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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
Page data
Type Project
Keywords building materials, ccat, cob, hempcrete
SDG Sustainable Development Goals SDG11 Sustainable citites and communities
Authors Solomon Clark
Published 2018
License CC-BY-SA-3.0
Affiliations Campus Center for Appropriate Technology (CCAT), Cal Poly Humboldt
Language English (en)
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