World’s Largest Dams

As one of the largest commercial concrete contractors in the country, we are always interested in learning more about large, impressive projects both in the U.S. and across the globe.  The last several decades has seen several extremely large dams built throughout the world.  

Back in 1935 when the Hoover Dam was finished, it was the tallest dam as well as the largest hydroelectric plant in the world for about thirteen years.  While it still is listed among the largest 20 dams in the world, it has not been the tallest or largest for a while.  Now record setting dams are rated according to the largest by volume, the tallest, and by production of the most hydroelectric power. 

Currently, heading the list for the largest dam by volume of construction material is the Syncrude Tailings Dam in Canada.  It is estimated that the dam required 706,320,000 cubic yards (540,000,000 cubic meters) of material to build and the structure is expected to grow larger as mining operations in the area grow.  To compare, the Hoover Dam took 3,250,000 cubic yards (2,600,000 cubic meters) of concrete to construct.  Another big difference is the Syncrude Tailings Dam is made from left over dirt from mining while the Hoover Dam is made of strong concrete.  

Today the tallest dam in the world is the Nurek Dam on the Vakhsh River in Tajikistan.  To compare, the Hoover Dam stands at 726.4 feet tall while the Nurek Dam is 984 feet tall.  The Nurek generates hydroelectric power and has a power station with an installed capacity of 3,015 MW.  

The largest hydroelectric dam in terms of installed capacity (22,500 MW) is the Three Gorges Dam on the Yangtze River by the town of Sandouping in China.  Constructed of concrete and steel, the dam is 7,661 ft. long with a height of 607 ft. above sea level.  The project required 27.2 million cubic meters (35.6×106 cu yards) of concrete and 463,000 tons of steel to construct.

The Conco Companies are a leading supplier of concrete services for the Western United States. We have built a reputation on superior concrete formwork, reinforcing, place and finish, shotcrete and other ancillary services that benefit from our vast experience.  We have four regional offices to serve Southern and Northern California, Oregon, Washington, Nevada and Colorado.

Source: usbr.gov/lc/hooverdam/history/essays/biggest.html 

Concrete – An Important Resource

Concrete is not only an extremely important resource in the construction industry, but to the very infrastructure of our country.  Almost all larger-sized buildings, bridges and other structures constructed today use reinforced concrete, which is comprised of steel rebar in the form of mesh, spiral and bars or structural fibers from other materials.  Concrete can also be “pre-stressed (reducing tensile stress) using internal steel cables (tendons), allowing for beams or slabs with a longer span than is practical with reinforced concrete alone.” 

The benefits of building with concrete are numerous and concrete mixes of today allow for all kinds of creative projects.  It is one of most sustainable building materials available and lasts for decades, especially when compared to wood, asphalt or other materials.  Furthermore, concrete structures are extremely fire resistant.

Another factor to consider regarding the importance of concrete to our economy is that it is produced here in the U.S; and it is estimated that the concrete industry provides over two million jobs to Americans.  Furthermore, the concrete used for a project is generally produced somewhere near the construction project, which reduces transportation and energy cost.  The Portland Cement Association (PCA) explains that the cement industry is regional by nature and that nearly 98% of U.S. cement is shipped to customers by truck with the rest by barge or train.

Even after several decades of use, concrete can be recycled into an aggregate that has a hundred or more different uses.  The National Ready Mixed Concrete Association (NRMCA) points out the fact that concrete is “green” as it does not have any toxic runoff as asphalt does and is produced locally from abundant local sources.  Thus the mere sustainability of concrete makes it a good choice both environmentally and economically.

At The Conco Companies, we are one of the leading concrete contractors in the Western U.S. and offer a wide range of quality services and products.  Our experience includes commercial, educational, parking and other construction development as well as public works projects.  We serve California, Washington State, Oregon, Colorado and Nevada.

Sources: en.wikipedia.org/wiki/Properties_of_concrete,

cement.org/cement-concrete-basics/how-concrete-is-made, 

nrmca.org/sustainability/Sustainable%20Concrete%20Pavement.pdf

Recycling Concrete Makes Good Sense

Even at the end of the lifespan of a concrete building, bridge or highway, the concrete used to construct it still has a use.  Since concrete is the most widely used man-made material in the world, it is important that concrete is recycled rather than taking up space in landfills as was done in the past.  Also by using recycled material as gravel, it reduces the need for gravel mining as well as reduces the amount of pollution created in making new concrete. 

Today concrete is routinely recycled and the aggregate produced is used to create new concrete or for a number of other purposes.  Recycling concrete from a building starts right at the site of the demolition.  Crews work to prepare the concrete by removing as many contaminates as possible by separating the concrete from material such as roofing, trash, and wood. 

Now the concrete is put through several steps such as crushing, pre-sizing, sorting, screening and the further elimination of any contaminants.  Typically it is cleaned by a water method in order to eliminate dirt and any other remaining materials.  It is critical that materials such as asphalt, sealant, chlorides and gypsum are removed.  

Also it is at the recycling facility where the reinforced steel (rebar) is removed.  This involves the use of huge magnets that attract and identify the steel for removal.  Once the rebar is removed, it is transported to plants that specialize in processing steel materials.   

If the recycled concrete is free of contaminants, it will be used as a dry aggregate in brand new concrete.  Another easy method to reuse concrete pavement is to break it in place and use it as a base layer for an asphalt pavement through a process called “rubblization.” Furthermore, there is a market for used concrete that has not been processed and screened as carefully.  This is used as an aggregate for fill, drainage, or as sub-base gravel before asphalt or new concrete is poured.

The Conco Companies' mission is to be the best supplier of concrete services in the Western U.S. and to bring experience, expertise and quality to each project. We continue to upgrade and expand facilities to better serve the growing market for a wide range of construction development. We have four regional offices serving California, Oregon, Nevada, Colorado and Washington.

Source: en.wikipedia.org/wiki/Concrete_recycling

Reinforced Concrete Made It Possible for 20th Century Structures

Late in the 19^th century, there were several significant advancements made in improving the method of reinforcing concrete.  In 1879 G. A. Wayss, a German civil engineer and pioneer in the construction of iron and steel structures, brought the German rights to patents developed a few years earlier by the Frenchman, Monier.  He went on to open the first commercial reinforced concrete business in 1884 called Wayss & Freytag.  Wayss is credited with establishing reinforced concrete as a scientific technique.       

Another contributor to the developing field of reinforced concrete was Ernest L. Ransome.  He is responsible for advancing the innovation and development of nearly all of the earlier techniques from previously known reinforced concrete inventors.  Among Ransome’s contributions was to patent “a system of ferro-concrete with the iron rods twisted to improve the bond, then develop a patented Ransome system for practical reinforced concrete construction.” His reinforced concrete structures quickly earned him a reputation and he was given the opportunity to build two of the first reinforced concrete bridges in North America.   

One of the bridges was the Alvord Lake Bridge built in 1889.  The bridge, which crosses the pedestrian entrance to San Francisco's Golden Gate Park, was constructed as a single arch that is 64 ft. wide with a 20-ft. span.  It, along with a couple of other reinforced concrete structures in San Francisco, survived the 1906 earthquake and fire in outstanding shape.  The bridge was designated as an American Society of Civil Engineers civil engineering landmark in 1969.  

Other first reinforced concrete projects include the Ingalls Building, a 16-story skyscraper built in 1904 in Cincinnati, OH, which was the first skyscraper in the world to be constructed with reinforced concrete.  Although it is currently for sale, the building is still standing and is a designated National Historic Civil Engineering Landmark.  Furthermore, reinforced concrete provided the strength and resistance to fracturing to allow for the construction of 20^th century projects such as the Hoover Dam and Grand Coulee Dam built in the mid-1930s.

The Conco Companies are a leading supplier of concrete services for the Western U.S.  We got our start in the Bay Area in 1959 by offering clients the best value on a wide range of concrete services and products.  Since that time, we have taken a leading role as one of the top concrete contractors in the region. We have four regional offices serving California, Nevada, Washington, Oregon and Colorado.

Sources: en.wikipedia.org/wiki/Reinforced_concrete, en.wikipedia.org/wiki/Alvord_Lake_Bridge