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.

How Do We Determine Which Pump to Use?

For any of you following our articles on Conco Now or our blog posts, you know that we have an impressive fleet of concrete pumps that has allowed us to successfully operate one of the largest concrete pumping companies in the U.S. for more than 40 years.  In fact in Southern California alone, we house 15 pumps manufactured by two of the top names in the industry, Putzmeister and Schwing.  So with all of the pumps that we own, how do we determine which is the best pump or pumps to use on a particular job?

This is where our experts come in.  They know how to deliver cost-effective solutions for even the most challenging projects.  Our experienced team designs customized plans for each specific project, which includes calculating the needs of a job right down to the type of equipment to use that allows us to meet deadlines and handle access difficulties.

By owning such a large range of different sized pumps, we are able to use the proper equipment to place concrete in the fastest, most efficient manner.  Some of our pumps are specifically designed to maneuver in tight spaces and within small jobsites while the reach of our long booms make them the appropriate choice for other projects. 

This is why it is so imperative to have a team of professional concrete contractors that have the experience to analyze all aspects of the job’s specifications to determine which boom truck has the capability and features to most efficiently handle the job.  Making the right selection of equipment before the job is started is critical to staying on budget and meeting timelines as well as providing a safe environment for our employees and the rest of the workforce at the jobsite. 

The Conco Companies have built an outstanding reputation in the Los Angeles area with our superior concrete formwork, reinforcing, place and finish, shotcrete and other ancillary services.  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.

Opportunities for Hard Working Construction Laborers

By Conco  

The Conco Companies continues to seek experienced carpenters, cement masons, ironworkers, operating engineers as well as job opportunities for construction laborers.  We have openings at all of our locations, which include Northern California, Southern California, Washington State, and Colorado.  These are union positions (with the exception of Colorado) and offer competitive wages along with medical and retirement benefits.

Conco’s openings for construction workers include Bridge Laborers and General Laborers.  The responsibilities include all work in connection with but not limited to: dumpman, load Spotter, flag person and operating a forklift.  We are an equal opportunity employer.

At Conco we employ a dedicated crew of laborers and cement masons who are some of the most experienced in the industry.  We provide crews with the most up-to-date equipment and tools to assist them with optimally performing each job and to continue to meet deadlines.  Additionally, Conco is committed to providing all employees a hazard-free, safe working environment.  

To achieve this goal, our safety program focuses on hazard elimination.  We sincerely believe that when safety is the first consideration before any work begins, everyone wins.  Safety pays for our company, our employees, our customers and the general public!

We are sure you will find our company is an exciting place to work.  We have had the privilege to be a part of many distinguished project throughout the Western U.S.  Recently we provided the concrete services for the San Francisco 49ers Levi Stadium.  Last fall we assisted on the repairs for the new Bay Bridge also in San Francisco.  Our most recent accomplishment was to break the world record for the largest continuous mat pour that was done for the Wilshire Grand Center in Los Angeles.
 

If you are interested in applying for a position, please refer to our website for more information.  

Conco is a leading supplier of concrete services for the Western United States. We have built our reputation with superior concrete formwork, reinforcing, place and finish, shotcrete and other ancillary services that benefit from our vast experience. With state-of-the-art equipment and modern facilities, we work diligently to meet goals and stay within budget.

Chemical Admixtures in Concrete

Chemical admixtures are natural or manufactured chemicals that are added to concrete along with portland cement, aggregate, and water.  They can be a liquid or powder and are added to the concrete immediately before or during the mixing process.  The chemical admixtures in a mix will account for less than 5% of the total concrete.   

The purpose of chemical admixtures is to give the concrete additional properties to handle circumstances such as pumping requirements or when placing concrete during extreme weather conditions.   According to the Portland Cement Association, “Admixtures are classed according to function. There are five distinct classes of chemical admixtures: air-entraining, water-reducing, retarding, accelerating, and plasticizers (superplasticizers).”

The National Ready Mix Concrete Association (NRMCA) says that the most common chemical admixtures used are air-entraining agents, water-reducers, and water-reducing retarders and accelerators.  They state that admixtures are added to concrete to increase “durability workability or strength characteristics of a given concrete mixture.”

Accelerators are used to increase the early strength of concrete by causing it to harden quicker and are used to protect concrete from extreme cold or when there is a tight project deadline.  Chemical accelerators are chloride based or non-chloride based and calcium chloride is one type commonly used as it is inexpensive.

Retardants are used to slow down or delay the hardening process such as in situations where the job demands a slower pour due to the scope of the project or when in very hot temperatures.  It provides a crew additional time to place and finish the concrete.   Common retardants are lignin, sugars, and citric and tartaric acids.

Air-entraining is the process of deliberately adding microscopic air bubbles into the concrete.  The purpose of doing this is to increase the concrete’s durability when faced with cycles of freezing and thawing conditions and to improve the concrete’s workability.    Furthermore segregation and bleeding is diminished or completely eliminated.  The only negative is that the concrete experiences a 5% reduction in strength for each 1% of air added.

1. http://www.cement.org/cement-concrete-basics/concrete-materials/admixtures
2. http://www.nrmca.org/aboutconcrete/cips/15p.pdf

Conco is one of the leading concrete contractors in San Francisco offering a range of innovative, quality services.  We have been honored to work on many high-profile projects and were recently awarded the concrete package for the San Francisco 49ers Stadium.  Our concrete services include commercial, educational, parking and other construction development as well as public works projects.

Methods to Measure Sustainability

The growing demand for green buildings has been invigorated by green building programs such as the LEED rating system.  With new construction projects, owners and builders alike are looking for materials that offer reduced operating costs, improved health benefits, and perform better environmentally throughout the life-cycle of the products. 

Although this can result in some confusion in assessing the impact of such materials on all of these aspects, there are many good resources being developed to assist in making informed decisions.  Experts working in the field of sustainable design are improving the methods that are used to more accurately measure the value of the return on the green investment. 

One of these tools is called a Life-Cycle Assessment (LCA) and is used in determining the actual performance of green building materials.  This cradle-to-grave assessment starts with a product evaluated by the impact of extracting the raw material, to the manufacturing process and distribution, to the durability and performance.  Additionally the ease of reusing or recycling the material is judged and taken into account. 

When considered early in the planning and design stages, sustainable criteria offer the greatest cost-efficiency as well as the best ability to influence design. Therefore, it is important that architects and owners have the most up-to-date information available right from the start of a project. 

Green products are typically made from reused or recycled-content or from renewable resources.  The EPA says the goal should be to promote clean air and reduce the emissions of VOC (volatile organic compounds) and formaldehyde.  They should not contain CFCs, HCFCs or other toxic substances and need to promote practices that conserve energy and water.  Furthermore they should offer good durability and ease of maintenance, and aid in reducing a building’s overall operating cost.   

The EPA concludes that green buildings should be designed to reduce the environmental impact on human health and the natural environment by:

·         “Efficiently using energy, water, and other resources

·         Protecting occupant health and improving employee productivity

·         Reducing waste, pollution and environment degradation”

 

 

 

 

Conco is a leading supplier of concrete services for the Western United States.  As one of the leading commercial concrete contractors in the San Jose area, we have been involved with large-scale projects in the area including the Mineta Airport.  Our concrete services include commercial, educational, parking and other construction development as well as public works projects.

 

 

 

Berkeley Bowl West Filled a Need in the Community

 

 

Conco has provided concrete services for an array of construction projects including that of helping to build a large grocery/produce store in Berkeley, CA.  The $30 million Berkeley Bowl West was built as a sister store following the popularity of the original Berkeley Bowl.  The new store is more spacious than the original one and at 140,000 sq. ft. became the largest grocery operation in the East Bay Area. 

The Berkeley Bowl West was built with both surface and underground parking, and provides a total of 211 parking spots that is twice the amount of parking at the original store.  The careful attention to parking was to ensure that the crowded parking situation at the Berkeley Bowl would not occur at the new store.   

The contractor for the project was Oliver & Company and the architect was Kava Massih Architects.  The engineer was Rutherford & Chekene and Conco provided the concrete work. The building was constructed with many sustainable features and was equipped by the Sun Light & Power company with 636 solar panels that powers much of the building’s operations.    

The interior of the Berkeley Bowl West is designed to have wider aisles to make for easier navigation than the original store and the produce and bulk food sections are both larger to meet the demand.  The store does not just offer groceries but has a wide range of prepared foods as well as a large café and kitchen area.  The building is spacious enough to house the offices for both of the stores, a warehouse, and a 3,000 sq. ft. community room.  A portion of the produce and meats sold are organic and much of it comes from local farms.

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 San Jose area.  With state-of-the-art equipment and modern facilities, we work diligently to meet goals and stay within budget.

 

Some of the Largest Concrete Pours

Conco’s regional office in Washington completed a 2,880 cubic yard mat pour using 275 tons of rebar for The Martin, a 24-story luxury apartment tower for general contractor Exxel Pacific.  The Martin is located in Seattle’s downtown area known as Belltown, adjacent to the Monorail, which made access and time constraints a concern.  

A total of three pumps were used - a 36 meter, 47 meter & 58 meter to complete the mat pour pumping 450 cubic yards per hour at peak times. Cadman, Inc. delivered the ready-mix with trucks arriving approximately every 80 seconds to fill the mat which measures 7′-6″ at the deepest point.

While we are proud of our accomplishment at The Martin, we are in awe of some of the world records set for concrete pours.  According to the International Union of Bricklayers and Allied Craftworkers (BAC), the largest mat pour in the U.S. was for the Venetian Hotel in Las Vegas.  It was a 22,000 cubic yard pour. 

BAC states the second largest pour in the U.S. was for the luxurious Trump Royale condominium, a 22-story, 386-unit building in Southern Florida that was done in 2007.  At the end of a very busy 24 hours, utilizing 190 trucks in constant rotation, and a 1500 man crew, 13,500 cubic yards of concrete were poured and 1,600 tons of rebar used. 

The world record for the largest concrete pour on a single project took a period of 17 years to complete.  The Three Gorges Dam in Hubei Province, China used an estimated 21 million cubic yards of concrete. 

There even stands a record for the largest continuous underwater concrete pour that was done in New Orleans in 2010.  It was for 10,251 cubic yards of concrete pumped over a period of 58 hours.   

As one of the leading commercial concrete contractors in the San Jose area, Conco has been involved with large-scale projects in the area including the Mineta Airport.  Our concrete services include commercial, educational, parking and other construction development as well as public works projects and highways.

Why Concrete Cracks

It is a fact that concrete is the best and most widely used building material.  It is far more durable that wood or asphalt and generally requires a lot less maintenance during its lifespan than other types of material.  While we understand the hardness and durability of concrete, we are also aware that it has the tendency to crack. 

Concrete contractors know this and work to mitigate many of the controllable conditions that create the cracks.  They use preventative methods when laying the concrete that can reduce and control the amount and type of cracks.  According to the Portland Cement Association, the most common type of cracks is caused by tensile stresses that develop with the slight change of volume as concrete dries.  This is the reasons that joints are placed in concrete pavement which allows for the shrinkage in a controlled manner, thus reducing cracking.

In most cases, cracks are not structurally damaging and are to be expected in foundations and slabs.  The three basic reasons for cracking are thermal temperatures difference, plastic cracking, and shrinkage cracking.

When cracks occur before the hardening is complete, it is most likely a result of settling or shrinkage in the volume.  The Concrete Foundation Association says that shrinkage of the surface (plastic-shrinkage cracks) is caused by loss of water while the concrete is still plastic.   The types of cracks that occur after the hardening process is completed are generally the result of drying shrinkage, thermal contraction, or subgrade settlement. 

Experienced concrete contractors know all of this and much more.  They understand the proper mix and type of concrete to help eliminate cracking and to prepare the concrete to withstand all the weather conditions it will face over the years.  

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 steadily taken a leading role as one of the Bay Area’s top concrete contractors.

The Early History of Concrete

The earliest evidence of concrete is from a naturally occurring event caused by a spontaneous combustion between limestone and oil shale in Israel more than 12 million years ago.  These deposits still exist today.  More recently and manmade, concrete was first used by the Egyptians around 3,000 BC.  They mixed mud with straw to bind dried bricks and later used lime and gypsum mortar for the binding agent when building the Pyramids. 

Through time, concrete was used to build many of the ancient structures of which some still exist today.  The Greeks first used lime mortars around 800 BC, which were much harder than what the Romans would later use.  There is even evidence that the Assyrians used a fully waterproof concrete to construct the Jerwan Aqueduct around 700 BC. 

Modern concrete is derived from the developments made during the Roman Empire.  The Romans widely used concrete from 300 BC - 476 AD, which made possible their revolutionary architectural designs that were structurally very complex and dimensional.  Some of the cement used was from a slaked lime found in volcanic ash called pozzuolana.

The Romans used the concrete to create buildings with arches, vaults and domes.  The most famous examples of building projects include the Roman baths, the Coliseum, the Pantheon in Rome, and the Pont du Gard aqueduct in southern France.  After the fall of the Roman Empire, the art of concrete was lost for many hundreds of years. 

An interesting fact is that modern tests have proven that Roman cement (opus caementicium) had as much compressive strength as modern Portland-cement concrete.  Of course, its tensile strength was much lower without the reinforcement of today’s 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 steadily taken a leading role as one of the Bay Area’s top concrete contractors. Our concrete services include commercial, educational, parking and other construction development as well as public works projects and highways.