A sidewalk made out of “lunar concrete” installed in downtown Hilo is being tested for its durability.

The Pacific International Space Center for Exploration Systems (PISCES), in collaboration with the Hawaii County Department of Research and Development, NASA, University of Hawaii at Manoa, and Kodiak FRP Rebar, installed the sidewalk Thursday.

The three prototype slabs were laid along Kinoole Street near Lincoln Park in downtown Hilo.

Instead of using cement, the slabs are made out of volcanic basalt fines – a waste byproduct found in local quarries – and each of the three slabs is “glued” together with a different binding agent: fly ash, baked basalt paver, and fly ash with basalt rebar. Rebar made out of basalt, instead of traditional steel, will be used to reinforce one of the slabs. Basalt rebar is 25 percent lighter than steel, twice as strong, and is extremely resistant to corrosion.

Researchers will monitor the slabs over a one-year period to see which binding agent is most effective, and analyze how well they hold up compared to traditional concrete.

For Hawaii, lunar concrete could prove to be a sustainable, green alternative. The state currently imports 300,000 metric tons of cement from Portland per year in order to meet demand. Cement production accounts for about five to seven percent of global CO2 emissions.

By developing homegrown cement, PISCES hopes to reduce the state’s economic and environmental costs associated with cement production.