Concrete is one of the world’s most polluting materials, accounting for between 5 and 8 percent of global CO2 emissions.

For the past several years, University of Auckland Engineering Faculty, Dr Enrique Del Ray Castillo has been researching and developing an alternative which could decrease the environmental impact of concrete by reducing the amount of cement required in its production.

Using a blend of volcanic ash – or pumice – and kaimoana shells, both of which are natural, local and more sustainable materials, Castillo has explored how traditional Roman engineering and mātauranga Māori could work together to make a material that’s built to last