Engineering researchers in the US have developed a new form of “smart” concrete which requires minimal levels of maintenance over the course of a lengthy service life.
The new composite concrete developed by civil engineering experts at the University of Wisconsin-Milwaukee (UWM) possesses remarkable levels of durability and water-resistance compared to conventional paving materials, resulting in a dramatically longer service life.
Developers of the material, which is referred to as the Superhydrophobic Engineered Cementitious Composite (SECC), estimate that it could possess an operational life of over 120 years, as compared to a maximum lifespan of 50 years for standard concrete roads in the area.
UWM researchers are currently in the process of testing these enhanced properties via the incorporation of "smart" features into a sample of SECC used to pave a driveway. The researchers have embedded electrodes approximately an inch below the surface of the concrete, and connected them to an adjacent data collection system.
The sensors will be able to determine how much water is seeping into the pavement, as well as the level of load and stress it bears as vehicles traverse it, thus permitting the researchers to better determine whether their material is performing as promised.
The key to the durability and longevity of SECC lies in two remarkable innovations developed by the UWM engineers.
The first innovation is unique compounds contained by the concrete which result in an extraordinary level of water resistance, which prevents liquids from permeating the material and exacerbating damage in frigid weather.
Water is usually capable of seeping through the cracks in conventional paving materials, causing significant damage when it pools and expands during freezing weather conditions.
The compounds in SECC, however, produce heightened water-resistance via the creation of microscopic spikes on the exterior surface of the material. These tiny spikes cause water to behave like an oily liquid when it comes into contact with the concrete, immediately beading into spherical droplets which roll off any angled surfaces with ease.
The second innovation of SECC is its heightened ductility, which enables the material to bend without fracturing or cracking.
UWM engineers managed to achieve this enhanced malleability through adulteration of the concrete mixture with super-strong unwoven polyvinyl alcohol fibres, each of which is the width of a human hair follicle.
These tiny fibres serve to stitch the material together, and prevent large cracks from occurring by permitting multiple micro-cracks to form instead. These micro-cracks diffuse heavy stress across the material while remaining too small in size to permit the entry of water.
According to the researchers, SECC possesses 200 times the ductility of traditional concrete, enabling it to withstand as much as four times the compression levels.
Given the greater expense involved in the production of smart concrete, its developers believe that it would be used in those critical construction points which are most susceptible to deterioration, such as bridge approach decks where bridges and roads join together.