Understanding the LEED’s Rating System

The Conco Companies offer our concrete services to projects throughout the Western U.S. and many of the prominent buildings we help to construct have received high LEED certifications.  The following is a short description of some of the criteria that is used in the rating system to determine LEED certification for buildings.  

LEED is an acronym for Leadership in Energy and Environmental Design and was started in 1998 by the U.S. Green Building Council (USGBC).  According to the USGBC, the green building certification program recognizes best-in-class building strategies and practice that have a positive impact on the health of occupants, while promoting renewable, clean energy.   

LEED offers third-party guidelines for the building industry to strive to design, construct, and operate buildings that provide the most optimal environments as possible while at the same time save money and resources.  With a membership of almost 20,000, the USGBC reviews and publically updates the standards every few years.  The key issue they promote is energy efficiency and protecting or using renewable resources. Today LEED certification is sought after and a higher endorsement can increase a building’s market value.

Buildings receive LEED certification based on specific guidelines and the higher the points for achieving those goals, the higher the certification.  Levels of endorsement include Certified, Silver, or Gold – right through to Platinum, the highest award.  The five basic categories of how points are earned are:  Sustainable Sites, Water Efficiency, Energy and Atmosphere, Materials and Resources, and Indoor Environmental Quality. 

Energy-efficient appliances and heating and cooling systems increase LEED certification as does using recycled materials.  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.     Endorsements are offered on residential homes, commercial and industrial buildings and entire neighborhood projects.

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.

Major Advancements in Concrete Formwork

The Conco Companies are one of the foremost providers of superior concrete formwork as well as place and finishing, reinforcing, concrete pumping and shotcrete services in the Western United States.  Over the last several decades, there have been major advancements in concrete formwork as a result of environmental concerns and in an effort to keep construction costs down.  There have also been changes to improve the health and safety of the workers.  At Conco we are committed to implementing and following the most stringent safety standards in the construction of formwork and in any of our other services.   

  

Formwork is simply the temporary structure built to contain and mold the poured concrete until it hardens into the required shape.  Its job is to control the concrete’s position and alignment and must be strong enough to support not only its weight but that of the concrete, the workers and any equipment or materials used in the process.  In order to meet the specifications of each project, concrete engineers, and architects take into account the quality, cost, and safety requirements as they design and implement forms. 

With the development of the newer types of forms, it has helped to improve safety, speed, and manageability on the jobsite.  In addition there are now a variety of materials used to construct forms and the choice of material will be based on the type of job it is required to do.  In the past, forms were mainly built out of lumber but now plywood, aluminum, and steel as well as custom-made plastic and fiberglass forms are commonly used.

After a form is built, the concrete is poured into it.  Once the concrete has hardened, the forms are disassembled or “stripped” to be used again.  Care must be taken not to strip the forms or remove the shoring before the concrete has sufficiently cured and is able to support its own weight.  Today, a lot of the formwork in the U.S is made from prefabricated modules, which allows the forms to be assembled on a jobsite quickly and in a cost-effective manner.  The modules can be reused thousands of times whereas older wood forms had to be replaced much sooner. 

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.

Reinforced Concrete Supports Modern Architectural Designs

Structural concrete or reinforced concrete is classified as precast or cast-in-place concrete and provides the required strength to allow many of today’s challenging architectural designs to be achieved.  The amount of steel that is embedded into the concrete is based on each project’s specifications and steel reinforcing bars (rebar) are commonly used.  The rebar is placed in a formwork or mold and tied into place with wire that is referred to as the reinforcement cage.  The concrete is then prepared following the design mix specifications and poured into the form to set and harden.   

The development of reinforced concrete has made concrete the most commonly used type of building material throughout the world.  It offers a higher tensile strength and ductility than concrete alone and absorbs the tensile, shear, and even at times the compressive stresses in a concrete structure.  It is the type of concrete typically used in the construction of dams, bridges, skyscrapers, columns, beams, frames, and foundations.   

Many large skyscrapers, such as the One World Trade Center Tower and the new Wilshire Grand Center in Los Angeles are being built with a cast-in-place, reinforced concrete core.   The reinforced core walls in the One World Trade Center are 6 ft. thick below grade and more than 3ft. thick above ground level.  On the upper levels the concrete is 2 ft. thick throughout the core of the building.  The Wilshire Grand, one of the current projects that The Conco Companies are busy helping to construct, will have a four-foot-thick reinforced core that surrounds the staircase in the center of the building.  Neither of these super tall skyscrapers could have been built without the use of today’s reinforced concrete. 

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 Aggregate in Concrete

The Conco Companies offer a range of services that include quality concrete formwork, reinforcing, place and finish, and shotcrete.  We also own a fleet of construction hauling trucks and operate one of the largest pumping companies in the U.S.  Our many years in the industry and extensive experience mean we have dealt with all types of concrete mixes.

Concrete is a mixture of cement, aggregates, and water and it is important to use the right type of aggregate as it influences the concrete mix in strength, durability, workability, hardening, and ultimately the cost.  The aggregate is an inert material that accounts for 60 to 75% of the volume, 70 to 85% of the weight and originates from sand, gravel or crushed stones.   Fine aggregate is typically defined as a mix of natural sand or crushed stones with a majority of particles smaller than 3/16^th of an inch or 5mm (although some define it as less than 4.75mm).  Coarse aggregate is crushed stones or gravel particles that are larger than 3/16^th of an inch or 5mm (or as some define it as larger than 4.75mm.).  

Generally the aggregate used in concrete mixes comes from natural sand or gravel pits, rivers, seas or lake beds, hard-rock quarries, or underground mines.  The type of materials used as the aggregate effect the concrete more when it is wet than once it has cured.  When the gravel is extremely rough or irregularly shaped, it requires more water in the mix as well as more cement to give it the proper consistency. 

Aggregate is prepared by crushing, washing, and putting it through a grading process.  Grading is important as it determines the paste requirements for the concrete and regulates how much of the costly cement will be needed.  According to the Portland Cement Association, “Although some variation in aggregate properties is expected, characteristics that are considered include: grading, durability, particle shape and surface texture, abrasion and skid resistance, unit weights and voids, and absorption and surface moisture.”

Source: cement.org/cement-concrete-basics/concrete-materials/aggregate

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.

The Development of Shotcrete

Conventional cast-in-place concrete and shotcrete share many of the same properties but shotcrete provides an advantage in placement.  It bonds with most substrates instantly or very rapidly, which makes it a good choice on complex forms or shapes.  Similarities to conventional concrete include high strength, low permeability and high durability.  It has a wide range of applications that include repair or restoration, ground support, architectural and landscape restoration, new construction and much more. 

Shotcrete, originally known as gunite, was developed by Dr. Carl E. Akely.  In his process, the dry material was blown out of a hose and water injected at the nozzle.  Akeley went on to patent his cement gun and the material he called Gunite.  During that period, he created the Cement Gun Company (now called Allentown Equipment).

In the mid-1950s, a wet mix method was introduced to the construction industry.  The benefits were recognized immediately and it was used on many projects.  Shotcrete became even more popular with the development of a rotary gun that had an open hopper which allowed the material to be continuously fed.   

The American Shotcrete Association credits the technical advancements in materials and equipment made in the 1970’s of providing an enormous improvement in the application of shotcrete.  They state that, “Perhaps the most significant step in this period was the development of efficient concrete pumps that could be used for wet shotcrete application.”

The 1980’s continued with advancements in the mixing and batching of ready mix concrete and the development of admixtures that allowed for consistency, hydration and performance.  Today one of the biggest changes to shotcrete applications is the ability of modern equipment to pump any slump as well as to pump it over long distances and up into high-rise construction projects.  

Sources:en.wikipedia.org/wiki/Shotcrete,shotcrete.us/,shotcrete.org/whyshotcrete/index.htm

The Conco Companies are leading suppliers 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.

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.

Today’s Modern Equipment Saves Time on a Jobsite

The Conco Companies are one of the top commercial concrete contractors and independent reinforcing steel and post-tension cable suppliers in the Western United States, and as such, we recognize the need to finish projects on time and on budget.  This is why we continue to purchase and utilize the most up-to-date equipment to help us successfully fulfill our commitments.  

As one of our lesser known pieces of timesaving equipment, Telebelts are designed to move heavy materials on or off a jobsite quickly and easily.  Telebelts are a mobile telescopic belt conveyor that is very versatile and comes in a variety of sizes.  This type of equipment is used to place high volumes of concrete, gravel, rock, and backfill fast and efficiently to save time and labor.  The set-up on a Telebelt is easy to do, and since it is mobile, offers the option to move around a jobsite as needed and is ideal for jobs that would otherwise have few options but to wheelbarrow material by hand.

Telebelts are fast and efficient with outputs up to 5 cubic yards per minute.  They are perfect for use in low clearance areas or under bridges and can go into limited access structures.  One example is a Putzmeister TB 130 that has a horizontal reach of 126’ 6” and a maximum rated capacity of 360 cubic yards an hour.  The unit has a 360 degree hydraulic rotation and a variety of hopper options.   

To demonstrate how we utilize Telebelts in a project, Conco recently had to backfill 2,900 tons of crushed rock in just three 8-hour days.  There was no room for error as any delay in placing the material would impact other jobs on the project.  To finish on time, we brought in our Direct Feed trailer which allows a Superdump, Transfer, End Dump or 10-Wheeler to unload its contents directly into the hopper attached to the trailer.  The material was then fed from the hopper onto one of our Telebelts.  The Telebelt placed the material directly at the point of placement, which all helped in our efforts to meet a tight deadline.

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.

How to Control Shrinkage and Cracking in Concrete

All concrete experiences some degree of shrinkage that can affect its long-term strength and durability as well as result in cracks.  Since shrinkage is an inherent property of concrete, it is impossible to totally eliminate cracking but it can be controlled.  Concrete engineers such as those at The Conco Companies work diligently to understand and address the issues associated with shrinkage.  

We know that shrinkage is caused by a loss of volume that occurs in different stages of the process but it is still a challenge to prevent or alleviate shrinkage, and thereby the cracking.  It is an especially important consideration on projects that involve large mat pours such as the ones that Conco is doing on the Salesforce Tower in San Francisco and recently completed on the Wilshire Grand in Los Angeles. 

According to the Portland Cement Association, “The shortening of concrete slabs can be caused by temperature decreases or moisture loss. These two causes are also related to curling and warping of slabs, respectively. Curling is the deformation of the slab due to a difference in temperature between the surface and the bottom of the slab (temperature gradient).  Slab “warping” is the deformation of the slab surface profile due to a difference in moisture between the surface and bottom of the slab (moisture gradient).”* 

To ensure the placement of concrete moves quickly, it is mixed with more water than what is necessary to hydrate the cement materials.  Once the concrete is placed, the excess water separates from the hardening concrete, which results in a loss of volume that causes the concrete to shrink.  The concrete’s reinforcement or base friction works to restrain it, which in turn can create tensile stresses in the slab causing cracks. 

In an effort to prevent the shrinkage, one of the things we do at Conco is to watch out for fluctuating temperatures during the first 24 hours after placement.  We also take considerable care to use the correct concrete mixture design so that the least amount of extra water is added and the largest size of aggregate is used.  All of this can work to help reduce shrinkage.

Source:cement.org/for-concrete-books-learning/concrete-technology/focus-on-floors/concrete-shrinkage

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 Importance of Concrete to the World Economy

Right behind water, concrete is the second most widely used substance in the world, and as such, it is an enormous industry with billions of tons produced annually.  In the United States alone, it is a $200 billion industry and more than 500,000 people are employed in some form of career that involves concrete.

The size of the industry reflects the versatility of concrete and its many applications.  It is used in the construction of roads, bridges, dams and public works as well as most office buildings, retail stores and parking structures throughout the world.  Concrete is also used in the construction of some of the safest, most energy-efficient homes.  In addition it is pumped up to extreme heights to build today’s skyscrapers and other building projects. 

Compared to wood, asphalt and most other construction materials, concrete is very durable and will last for decades.  And unlike other materials, it gets stronger as it ages.   Also it is extremely good at standing up to natural disasters such as earthquakes, hurricanes and floods.  Add to that the fact that it is fire resistant to make it one of the safest construction materials available.   

Even after several decades of use, concrete can be recycled into an aggregate that has a variety of different uses.  It is commonly used as backfill or as gravel in new construction projects.  The National Ready Mixed Concrete Association (NRMCA) points out that concrete is “green” as it does not contain 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.

Sources:concretehelper.com/concrete-facts/,en.wikipedia.org/wiki/Concrete_Industry_Management

When your project demands exceptional services and the best value, The Conco Companies 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.