Increasing the Tensile Strength of Concrete

The aggregate in a concrete mix effectively carries the compression load to make concrete strong in compression.  However concrete is weak in tension as the cement holding the aggregate in place is susceptible to cracking and can result in the structure failing.  To carry the tensile load, concrete is reinforced with steel reinforcing bars (rebar), steel fibers, glass fibers, or plastic fibers.

Both brittle and rigid, concrete may crack or break under high pressure conditions and shear stresses caused by wind, earthquakes, and other forces.  By embedding rebar or other reinforcement into the concrete, it provides a higher tensile strength and ductility to the concrete and gives buildings the required strength to stand up to seismic activity. 

Generally concrete only needs a relatively low percentage of rebar to achieve the maximum performance required for a specific construction project.  In a typical concrete beam, about 1% of rebar is added to the concrete, while in a column, it can be up to 6% rebar.  This formula achieves an economical solution for providing strength, ductility, and durability to the construction project since the cost of steel far exceeds the cost of concrete.

Types of reinforced concrete include precast or cast-in-place and are used in the construction of slabs, walls, foundations, beams, and columns.  Many structures built today would not have been possible without reinforced concrete.   Another type of reinforcement is referred to as post-tensioning.   Wikipedia states, “Bonded post-tensioned concrete is the descriptive term for a method of applying compression after pouring concrete and the curing process (in situ). The concrete is cast around a plastic, steel or aluminum curved duct, to follow the area where otherwise tension would occur in the concrete element.” 

Precision-engineered rebar and post-tension cable is fabricated in state-of-the-art facilities such as the plants owned by The Conco Companies.  We utilize the latest technologies to ensure accuracy and increase productivity.  Our plants are outfitted with modern shear lines, benders and post-tension cable manufacturing equipment to meet the most exacting specifications. 

Source: en.wikipedia.org/wiki/Concrete

When your project demands exceptional services and the best value, Conco can deliver.  We have been offering premium concrete services throughout the Western U.S. since 1959, and have four regional offices serving California, Washington, Oregon, Nevada and Colorado. With state-of-the-art equipment and modern facilities, we work diligently to meet goals and stay within budget.

Improved Efforts in Recycling Concrete

Several decades ago, used concrete was simply hauled away to landfills for disposal.  While this presented a quick solution for getting rid of the concrete, it not only started filling up landfills but was viewed poorly from an environmental standpoint.  The fact is concrete is a fairly easy material to recycle and can be reused in a variety of ways.  Even after many decades of use as a building or highway, the concrete can be recycled and used again in other construction projects.    

Today once a building has outlived its usefulness and is ready to be demolished, crews prepare the concrete by removing as many contaminates as possible such as roofing, trash, wood, and other materials.  The more care that is taken at the jobsite helps to improve the quality of the ensuing product once it is recycled.  Furthermore, unless the concrete has been reasonable cleaned, many recycling facilities will not even accept it.

Once at the recycling facility, huge magnets are used to attract and identify the steel for removal.  All of the reinforced steel (rebar) in the concrete is removed and sold to rebar fabrication plants where it can be reused to make new rebar.   

During the recycling process, the concrete is put through several steps that involve crushing, pre-sizing, sorting, screening and further elimination of contaminants.  It is cleaned by a water method to get rid of dirt and other remaining materials.  Care is taken to get rid of any remaining materials such as asphalt, sealant, chlorides and gypsum.  

Even concrete that has not been as carefully processed and screened has a use in the industry. This type of aggregate is sold for fill, drainage, or as sub-base gravel before asphalt or new concrete is poured.

Conco is a leading supplier of concrete services for the Western United States. 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, Washington, Oregon, Nevada and Colorado.

The Greenest Buildings in America

Most experts agree that a LEED Platinum certification or the equivalent is the standard for sustainable designs that clearly identify the best energy and water efficient buildings.  Other systems for rating green building are Green Star in Australia, DGNB in Germany, BREEAM in the UK, and CASBEE in Japan.  Generally accepted as the leading international standard, LEED ratings are being used to rate projects throughout the world.

By recognizing what constitutes the best green standards and how well a design translates into actual performance, we can gather data to be used for future projects.  Engineers, architects, and builders have taken the challenge and are moving forward to create greener office buildings, homes, and industrial parks.

It is recommended that the decision to build green is done as early as possible in the design stage as even the site choice can be a factor.  It will help to reduce costly missteps down the road.  A few examples of some of the greenest buildings in North America are:

·     Manitoba Hydro Place in Winnipeg, Canada – extensively used recycled building materials and has geothermal and thermal accumulators for heating/cooling.

·      Bank of America Tower, New York City – currently holds the distinction of being the only skyscraper with a Platinum LEED rating in the U.S.

·      Genzyme Center in Cambridge, Mass. – has a beautiful 12-story central atrium that allows for 75% of the employees to work in natural light.

·     Twelve West in Portland, Ore. – is equipped with four 45’ high wind turbines mounted on the roof and provides 9,000 kilowatt hours of energy per year.

·   Charles David Keeling Apartments, La Jolla, CA – receives extra points for utilizing the building’s site to its maximum potential and regulating temperatures with thermal mass.

Discover the experience of working with one of the top professional commercial concrete contractors in the Colorado Springs area.  Conco has been in business since 1959 delivering first-rate concrete services and has all the experience and expertise to handle even the most challenging projects. 

What is LEED?

LEED is a nationally recognized organization that stands for Leadership in Energy and Environmental Design.  It was started in 1998 by the U.S. Green Building Council (USGBC).  The purpose of LEED is to provide third-party guidelines for the building industry to design, construct, and operate buildings that provide the most optimal environment as possible. 

The standards that LEED is comprised of are reviewed and publically updated from time to time by the USGBC membership that numbers close to 20,000.  Energy efficiency and protecting or using renewable resources are some of the key issues that LEED promotes. 

They provide certifications to buildings based on their specific guidelines and the higher the points for achieving those goals, the higher the certification.  Buildings receive the endorsement of Certified, Silver, or Gold – right through to Platinum, the highest award.

There are five basic categories for which points are earned:

·         Sustainable Sites

·         Water Efficiency

·         Energy and Atmosphere

·         Materials and Resources

·         Indoor Environmental Quality

Extra points can be achieved through special recognition of Innovation in Design and Regional Priorities.  Regional points are earned when a builder has taken care to lessen or eliminate the harmful impacts on a sensitive, local environment.   

Even things like installing energy-efficient appliances and heating and cooling systems will increase the LEED certification.  The same goes for using recycled materials.  LEED endorsements are used for residential homes, commercial and industrial buildings as well as whole neighborhood projects.   

The organization states that new construction buildings with a LEED certification have a higher market demand than non-LEED certified buildings.   Not to mention the healthier environment for the occupants.  

When your project demands exceptional services and the best value, Conco can deliver.  We have been offering premium concrete services throughout the Western U.S. since 1959, and have a regional office in the Denver area.  With state-of-the-art equipment and modern facilities, we work diligently to meet goals and stay within budget.

Making Concrete More Environmentally Friendly

Water is the only substance in the world that is used more than concrete.  Concrete is the material that is used to construct most of the buildings in our cities, highways, bridges, and great entertainment venues like football stadiums and theaters.  It is readily available and made from abundant resources found locally.  Concrete has a long life-span and can be recycled once a building or other structure outlives its usefulness.  The industry provides millions of jobs right here in America.   

An article from the Smithsonian.com reports that in 2010, the world produced 3.6 billion tons of cement and that figure is only expected to go higher in the future.  So the only problem with concrete is that in the process of producing cement, which is an essential ingredient in concrete, it sends carbon dioxide gas into the atmosphere. 

The making of cement involves heating a mix of limestone and other minerals in large kilns at temperatures over 2700 degrees F with fossil fuels to run the kilns.  Scientists estimate that the production of cement ends up creating 5% of the human-generated carbon dioxide (CO2) believed to contribute to global warming.  

Obviously we are not going to stop using concrete and there is a lot of research being done to come up with solutions.  Furthermore we must factor in concrete’s sustainability to mitigate the environmental impact. 

In terms of research, one recent study from the Niels Bohr Institute at the University of Copenhagen reports successfully making stronger cement out of waste ash.  Waste ash is a by-product from sugar production.  The research indicates that “the ash helps to bind water in the cement so that it is stronger, can withstand higher pressure and crumbles less.  At the same time, energy is saved and pollution from cement production is reduced.”

*Read more: http://www.smithsonianmag.com/science-nature/Building-a-Better-World-With-Green-Cement.html#ixzz2jzJBadNX

from @SmithsonianMag on Twitter

*Taken from an article from the University of Copenhagen - Niels Bohr Institute (2013, September 16). Environmentally friendly cement is stronger than ordinary cement.

Discover the experience of working with one of the top professional commercial concrete contractors in the Colorado Springs area.  Conco has been in business since 1959 delivering first-rate concrete services and has all the experience and expertise to handle even the most challenging projects.

Is There a Difference Between Concrete and Cement?

Well it turns out we should probably be calling a cement mixer a concrete mixer and our cement sidewalks should really be known as concrete sidewalks.  Cement is one of the ingredients that go into making concrete.  Concrete is made with cement and an aggregate (coarse gravel or crushed rocks - generally limestone or granite, and sand) that is mixed with water. 

The cement is what binds the concrete together and is about 10-15% of the mixture that makes up the concrete.  Today almost all cement is Portland cement which is a generic term and is a combination of such ingredients as limestone, calcium, silicon, iron, and aluminum. 

All of the ingredients are heated in large kilns at extremely high temperatures to create pellets which are known as clinkers (somewhat like marbles). The clinkers are finely ground and gypsum is added to create the grey powder of cement.

Portland cement is hydraulic cement that is hardened in the concrete mix through a process of hydration and chemical reactions.  This type of cement is not dependent on exact water content.   In this process, as concrete ages it even becomes harder.

Concrete is mixed up in a variety of ways for different types of applications.  One of ways to make a stronger concrete is to add more cement into the mixture.  Once more cement is added to the mix, less water is used.  The size and type of aggregate used can also determine the strength of the concrete.  Larger size rocks can mean less cement is added, and less water is needed, making for stronger concrete.  Generally the aggregate is a combination of rock sizes.   

When your project demands exceptional services and the best value, Conco can deliver.  We have been offering premium concrete services throughout the Western U.S. since 1959, and have a regional office in the Denver area.  With state-of-the-art equipment and modern facilities, we work diligently to meet goals and stay within budget.