UNM researchers explore cool and renewable sidewalks

Research students with The University of New Mexico’s Civil, Construction and Environmental Engineering program are looking at ways to reduce material usage and heat on sidewalks. The concrete paths absorb heat, occasionally buckling because of the pressure from heated expansion; and can even reflect heat, causing “heat islands” in urban areas.

A Federal Highway Administration report updated this year noted that “Surface and near-surface heat islands can potentially affect human thermal comfort, air quality, and energy use of buildings and vehicles. Atmospheric heat islands can affect communities by increasing summertime peak energy demand, electrical grid reliability, air conditioning costs, air pollution and GHG emissions, heat-related illness and death, and water quality.”

As part of the 2021 EPA P3 Student Design Competition, UNM undergraduate and graduate students designed a sidewalk built using recycled and less energy- and carbon-intensive materials. Their technical challenge also called for the sidewalk to be the thinnest possible thickness in order to reduce material use and limit heat storage capacity.

UNM’s team consisted of Brittany Antonczak (Ph.D. Student, Civil & Environmental Engineering), Amanda Baldridge, Edgar Hernandez, Logan Hutchison, Mohammed Amin Najvani, Stephen Montaño (MS Civil & Environmental Engineering), Angel Padilla, Patience Raby, Matthew Ricks, Michael Suarez.

“We looked into the history of sidewalks as best we could, but came up largely empty-handed,” researcher Patience Raby said, while virtually presenting the team’s findings. “It seems there was not good explanation for the use of standard concrete mixes in sidewalks or even for the fact that they’re usually four inches deep.”

The researchers fabricated three slabs to compare their thermal output, emissivity, and energy balance. They gained valuable information on the impact of design but have yet to test the thermal and structural designs of their designs.

Researchers began the study before the pandemic. They report the shut down evoked by COVID-19 has lengthened original timeline of the study. Going forward, the team hopes to work in a small design group to continue their research.

In the future, the team would like to design 3D printed concrete slabs and those which are thin fiber reinforced with voids. These slabs would later be tested for heat storage potential. If resources allow, the team will also gather more data about thermal properties and real-thermal characteristics.

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