Cold pavement, a building material that could combat climate change
Scientists relate the temperature and color of the pavement to know which of its compounds can have a negative impact on the environment.
Researchers at the Massachusetts Institute of Technology (MIT) have developed a pavement that could mitigate greenhouse gas emissions. The pavement's innovative feature is its ability to regulate surface temperature, which, for the moment, are impenetrable due to the density of the materials with which they are constructed.
Pavements are an abundant urban surface that covers about 40% of the cities in the United States. In addition to being the means of transportation in the U.S., they are a source of heat that can increase air temperatures by up to 4.2 degrees Celsius.
In response, scientists at MIT Concrete Sustainability are studying how a surface can decrease the intensity of the heat it emanates. Their research focused on "Cool Pavements," that is, a pavement that reflects more solar radiation and emits less heat compared to conventional paved surfaces.
Their report describes how cool pavements can reduce air temperatures by as much as 2.1 degrees Celsius and 1.7 degrees Celsius in the cities of Boston and Phoenix, respectively. "Achieving these savings requires cold pavement strategies based on climate, traffic and the configurations of each city," said Hessam AzariJafri, co-author of the study.
Hessam AzariJafri also explained that surfaces with a low albedo (a metric for measuring the reflectivity of a surface), absorb more light and tend to be darker. In contrast, when surfaces have a high albedo index they are brighter and reflect more light.
Some materials such as concrete are able to reflect sunlight to regulate the temperature of the pavement, and lower the temperature of buildings. "Surfaces with a high albedo index tend to be brighter and reflect more light, this allows them to have lower temperatures," AzariJafri said.
For a comprehensive understanding of the environmental benefits of cold pavements, the researchers had to look beyond the conventional materials with which roads are built. This resulted in a classification of three types of pavement: reflective asphalt, concrete, and reflective concrete.
This classification also allowed them to analyze the impacts incorporated for all pavement types and the effect of pavement type on excess vehicle fuel consumption. "We did an analysis of the environmental impact of pavement by calculating three factors the stiffness and deterioration rate of the surface" AzariJafri noted.
So far, MIT scientists are working on a new project, which will allow each of the materials to be studied in depth with the goal of creating more environmentally friendly cement. To this end, it wants to guide future fresh paving projects for highways and roads in the United States to help cities and address climate change.
