Resilience can be understood as the capacity to anticipate and minimize potential destructive forces through adaptation or resistance. Basically addressing changes in the environment, whether gradual (such as climate change) or more abrupt (such as hurricanes) or immediate (such as a terrorist attack), require actions to mitigate their negative effects. In this section we’ll look at some disruptive conditions and how concrete can help mitigate the impact. Then we’ll look at the wide range of concrete structures that provide the places that play host to our lives, bring us together, and enrich our experience.
Organizations, institutions, businesses, whole communities even, prefer to function unimpeded. Transportation infrastructure, emergency and governmental services, basic business operations and productivity – all rely on roads, infrastructure, and buildings performing as intended. Yet we are very vulnerable, whether we’re talking about BIG scale disasters from natural forces and human conflict, or personal disasters like a fire.
Although the frequency of natural disasters has not increased in the last 40 years, their economic costs are rising dramatically. A growing share of our population and economic activity is being concentrated in disaster-prone places: along seismic zones and coastal areas. Critical infrastructures and other essen¬tial services have enabled us to thrive and grow and become increasingly interconnected to global economies. Unfortunately, a disruption at one location can have cascading consequences impacting business, health, and security. A wealthier world has more wealth at risk.
While sustainability often focuses on restoring balance, managing growth, and other such efforts to shift our future course, the fact is that disaster mitigation and management are central to a sustainable future. Hazard mitigation is a resilience strategy that saves lives and money. For a building to be truly sustainable it should be resilient. It should consider potential for future use and re-use and have a long service life with low maintenance costs. In addition, a sustainable building should be designed to sustain minimal damage due to natural disasters such as hurricanes, tornadoes, earthquakes, flooding and fire.
Flooding is the most common natural disaster in the U.S. Concrete withstands water damage well and can be more readily cleaned and disinfected than other materials, reducing overall clean up costs. Pervious concrete and concrete pavers can also help reduce the risk of flooding. Indiscriminate growth and development has drastically changed the drainage and run off patterns across the country, exacerbating flood risks in many areas. Flooding is a natural process along streams, rivers, and coastal areas, where water spreads out and distributes soils and organic matter across a wide area. Concrete can’t help us decide where to build, but it can help us reduce the impacts of building and paving to avoid making normal flooding patterns extreme and new areas susceptible.
During an average year in the U.S., there are 10 tropical storms, six of which become hurricanes, and over 800 tornadoes touch down. In addition, severe winds can develop and cause damage in any area. Texas TechUniversity’s Wind Science and Engineering Research Center conducted Construction Material Threshold Tests, in which they fired 2x4 projectiles toward a wide range of wall assemblies. They found significantly higher performance in the concrete structures, particularly insulated concrete forms (ICF). To achieve a comparable performance, framed walls required additional framing, sheathing and steel plates. These wood/steel assemblies would no doubt eliminate any first cost advantage without providing the other benefits of ICFs, such as energy performance and noise reduction.
Fires kill more people than all other natural disasters combined— 3,438 in 2008, including 118 firefighters, and there were over 5 times as many injuries. The US Fire Administration estimates property loss at $15.5 billion. These statistics are among the highest in the world. Why is that the case, when the US is so technologically advanced? One reason is that 70% of the world lives in concrete structures; in the US that figure is around 15%.
Concrete provides the best fire resistance of any common building material. It’s inorganic composition does not burn, it cannot be 'set on fire' like other materials, nor does it emit any toxic fumes or smoke when exposed to fire. The thermal mass properties of concrete–slowly absorbing and releasing heat work to mitigate fire risk. The slow rate of heat transfer and inherent fire resistance of concrete make it tolerate fire exposure and slow the spread of fire. Since it doesn’t burn, concrete doesn’t ignite, nor does it release toxic fumes or smoke, nor melt when it is exposed. In addition to making sense in wildfire-prone areas like California, concrete may reduce insurance rates for any building owner since it is at lower risk of loss due to fire from other sources. Concrete roof tiles, cast or masonry walls, fiber cement siding all help to secure structures against damage from fire.
Concrete's ability to withstand wind-borne debris and fire highlight its suitability for structures that may be susceptible to terrorist or military attack. Unfortunately Mother Nature isn’t the only risk we face these days, and making sure that potential targets are less vulnerable is an important consideration in new construction. Testing has demonstrated concrete’s ability to withstand bullets and blasts, further safeguarding the inhabitants.
In addition, disasters, whether natural or man-made, disproportionately affect the poor. Many structures that house low-income families are relatively unsafe with respect to these hazards, either because of poor structural quality or risk-prone locations. Such families are far less likely to have the resources to prepare themselves for catastrophes. If we are to take social equity seriously, we must deploy—and insist on—much higher performance standards in construction. Building with concrete systems sets equal disaster resilience standards for all citizens and would clearly offer greater social justice.
Construction and Maintenance
Everyday construction and maintenance can disrupt transportation routes. New building construction can also be disruptive, and lengthy construction time also keeps the new structure from starting service. Concrete structures help alleviate these impacts. Concrete roads last, requiring less rehabilitation and reconstruction. Some of the country’s concrete highways have lasted over 50 years, serving far higher traffic volumes than their designed capacity. Resurfacing techniques like grinding extend their life and can be sequenced to minimize peak traffic interruption. New construction of concrete can go in quickly, saving months of disturbance. Concrete buildings endure as well. Rehabilitating and reusing existing structures reduces the impact on neighboring properties and reduces waste. Buildings intended to last for hundreds of years, or areas where they already have, convey a sense of stability and permanence.
As we live in closer quarters and strive to design livable cities, the ability to get away from the noise of traffic, nearby businesses, and neighbors is important. Concrete can provide attractive sound barriers to buffer the sound along transportation corridors. Concrete buildings can measurably reduce sound transmission between residential units, giving occupants more privacy and calm.
Schools are places of learning where speaking and listening are the primary communication modes. The large body of research describing the significant negative effect of noise and excessive reverberation on the learning process is making communities aware of the importance of good acoustics. Concrete walls systems provide the necessary performance requirements to meet the needs of healthier environmental for teachers, students and their voices.
Another element of stability that concrete provides is energy performance. Concrete products figure heavily in efforts to design and build zero energy homes and buildings. ICF offers seamless walls that reduce air infiltration and provide superior insulation. A wide variety of concrete construction styles and materials provide a pallet to designers to create a building that works with the micro climate - the essentially free energy that wind and sun provide on a site. This can include bringing the structural support into the interior through post tensioning or columns, leaving floor plates with greater access to daylight and views. Concrete floors and ceilings can be designed in several ways to serve as thermal mass, moderating temperature swings, and using the sun and shade to heat or cool the space. This approach to thermal comfort relies on radiant heat transfer, which is more comfortable to most. Radiant hydronic heating can use solar hot water. The less our buildings rely on fossil fuel use, the less vulnerable we are to unpredictable utility prices. Even water can be managed more efficiently with concrete. Underground cisterns are central to many systems designed to harvest rain water, reducing the use of treated drinking water and leaving it for irrigation and other non potable uses.
Concrete pavements and “cool roofs” also provide a reflective surface that minimizes the urban heat island effect. This reduces the cooling load in our demanding urban commercial building cores, thus saving operational energy use. Urban heat islands are primarily attributed to horizontal surfaces such as roofs and pavements that absorb solar radiation. Cities and urban areas are 3 to 8 °F (2 to 4°C) warmer than surrounding areas due to the heat island effect. This temperature difference is attributed to more buildings and pavements that have taken the place of trees and vegetation.
Importance of Place
Beyond feeling safe and protected from the elements and extremes, buildings and infrastructure form the base on which we connect as communities, as families, as a society. Roads, bridges, ports, and utility infrastructure are essential for us to function safely and efficiently. Concrete provides the places where we worship, work, sleep, gather to hold court, exercise, watch sporting events, listen to music, learn, and seek health care and protection. It does so with unparalleled durability and strength, and with limitless shape and style.
Related Case Studies