Robert Digitale, THE PRESS DEMOCRAT
A Napa company is working to significantly reduce greenhouse gas emissions by offering an alternative way to make the most common construction material on the planet: concrete.
Watershed Materials recently received a $743,000 grant from the National Science Foundation to make concrete blocks without cement. Already, in an earlier grant phase, the company demonstrated the scientific feasibility of its proposal and produced a masonry block made with only half the regular amount of cement.
Under the grant, the company now seeks to develop both the cement-less blocks and the machinery needed to mass produce them.
“Cement is a really, really good glue,” said Watershed President David Easton. “But what we’ve discovered is it’s expensive and hard on the environment.”
Portland cement, which binds together sand and gravel to form concrete, is made in kilns using intense heat, a process that releases carbon dioxide from the limestone and other ingredients in the mixture. Its production is deemed responsible for more than 5 percent of the world’s greenhouse emissions.
“The making of cement is second only to automobiles and coal-fired electrical plants in the amount of CO2 it generates,” said Robert Courland, author of the book “Concrete Planet.” Courland hasn’t studied Watershed’s operation, but he said other businesses and researchers also are seeking “the Holy Grail” — a material that would be both more permanent and environmentally friendly than today’s concrete.
Easton brings more than four decades of construction experience as the founder of Rammed Earth Works. The Napa company builds homes and other structures from rammed earth, a mixture of clay-like, mineral-laden subsoils and a little cement that is tamped down in forms to build thick, sturdy walls. The process relies on techniques developed by ancient cultures.