[i] Concrete is the major material when engineering and building mass structures such as gravity dams or interstates. Citing these two types of structures shows the positives and negatives associated with concrete. While concrete is very strong under compression, it is extremely weak under tension. For this reason, reinforcements such as rebar are added to increase the tension strength. Another benefit of concrete is that it continues to cure and increase in strength long after the installation. The addition of additives directly into the concrete, such as silica fume, can also help to increase its life span. The largest amount of concrete used to date in a single structure is the Three Gorges Dam in Hubei Province, China. The estimated amount of concrete used was 28 million cubic meters over a seventeen-year period.[ii]
Thermal Properties of Concrete
The energy efficiency of concrete is another reason for its prolific use. Concrete walls leak less air than that of wood, and the thermal mass properties increase the efficiency of the structure. By storing and releasing energy, concrete helps to reduce major temperature swings and increases the thermal management ability of the building. Concrete structures also withstand severe weather such as high winds and hurricanes better than their wooden built counterparts due to its lateral stiffness.
While there are some enormous benefits to the use of concrete, the environmental footprint left behind is just as big. As mentioned above, the CO2 created during the manufacturing process is a reason for concern as we continue to grow and expand the infrastructures around the world.
New Engineering Technologies
One of the new technologies available today to help with emissions is a process that uses waste materials and Low Temperature Solidification (LTS) to produce concrete like materials. The New Jersey based company, Solidia Technologies™, creates this material utilizing the patented process invented at Rutgers for CO2 sequestration. With this process, concrete and cement emissions during manufacturing are reduced up to seventy percent.[iii] Waste materials, natural minerals, as well as CO2 are combined under low temperature and low pressure settings to create a plastic and stone type building material that is stronger and more impact resistant than concrete or natural stone. Also due to this process, carbon emissions are actually removed from the atmosphere during formation, instead of released into the environment. This material provides the construction industries a viable product with cost savings, superior performance, and an enhanced sustainability profile. [iv] This process not only results in a stronger and more stable product, but is also extremely commercially viable.
Another positive benefit of this process is the reduction of landfill material. Concrete, and concrete related by-products, account for approximately17 percent of the world’s landfill. As we continue to construct and replace structures, this number could increase quite rapidly.
While it is unlikely that concrete and cement will not be used in construction, it is a possibility that a more eco-friendly alternative will be used in the near future.