The Conco Companies provide a wide range of concrete services including concrete reinforcement for all of your rebar fabrication and installation needs. By owning and operating two large rebar fabrication facilities in California and Washington, we have the capacity to cost-effectively serve our customers’ needs saving them both time and money. Also Conco’s highly skilled crews are trained on the specialized tools used to fabricate, assemble, and install the rebar.
One example of a current job that we are providing a wide range of concrete services for including reinforcement is 970 Denny Way in the South Lake Union neighborhood in Seattle, Washington. Along with the 4,900 cubic yards of concrete we poured to form the 15,300 square foot mat foundation, we also provided the required 1.3 million pounds of rebar. Another recent project that took advantage of Conco Reinforcing’s services was a parking structure for the new Stanford Hospital in Palo Alto, CA. Our crews constructed two levels below grade, one level at grade and two levels above grade to total the approximately 397,359 square feet parking structure. To complete the project, we supplied 4.2 million pounds of reinforcing steel as well as 17,000 cubic yards of concrete and 1,200 cubic yards of shotcrete. The VA Mental Health and Research Center that is currently under construction in Seattle is a prime example of the benefit of using Conco’s full range of concrete services. On this particular project our job duties included concrete pumping, formwork, place and finish and shotcrete services on the 203,000 square foot structure as well as supplying and installing the reinforcement. When you take advantage of Conco’s unique ability to supply rebar and formwork on your next project, it eliminates the need for coordination between different suppliers. It also helps to ensure you meet timelines and stay on budget. Conco’s mission is to be the best supplier of concrete services in the Western United States and to bring expertise, experience and quality to each project. We continue to upgrade and expand facilities to better serve the growing market for public works projects, commercial, parking structures, educational, and other construction development. We serve California, Washington State, Oregon, Colorado and Nevada.
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At The Conco Companies, our shotcrete services provide an excellent alternative to traditional cast-in-place walls. Since shotcrete is pneumatically placed, it virtually eliminates the forming process, saving time and money, while still offering the same structural characteristics as traditional concrete methods. It is used for a wide range of applications including retaining walls, shear walls, and architectural walls as well as soil nailing and slope pavement.
An example of a project that Conco provided cost-effective shotcrete solutions for was the Mark, a 48-story high-rise tower in Seattle, WA. The 528,000 sq. ft. building consists of Class A+ office space and the luxurious 189-room SLS Hotel and Spa. In addition to the 5,000 cubic yard mat foundation pour we did that required almost 500 truckloads of concrete, the project included a sub-level parking structure with shotcrete perimeter walls and a concrete elevator core. A few years ago we also served as the General Contractor on a design-build parking structure for the Brio apartment complex in Walnut Creek, CA. The project included the construction of a five-story; cast-in-place parking structure with stalls for 471 vehicles and chargers for electric vehicles. To complete the project we placed 159,028 square feet of concrete, 750,000 lbs. of reinforced steel, and 1,500 cubic yards of shotcrete. Another type of shotcrete project we worked on was the Enfrente Pathway, a 0.6-mile, multi-use trail that provided a critical link to central and south Novato. Soil nails were installed to retain the hillside and we applied sculpted shotcrete as a finish over the walls. Depending on the type of application, a shotcrete mix can be customized with additives or admixtures. For instance when silica fume is added, it reduces permeability, increases the compressive and flexural strength, and offers better resistance to alkali and chemical attacks. To improved pumpability and adhesion in wet-process shotcrete and for freeze-thaw durability, air-entraining admixtures can be added to the shotcrete. To control cracking and improve impact resistance, different fibers are used or accelerators are added to improve placement characteristics in adverse conditions or increase production capabilities. The Conco Companies’ mission is to be the best supplier of concrete services in the Western United States and to bring expertise, experience and quality to each project. We continue to upgrade and expand facilities to better serve the growing market for public works projects, commercial, parking structures, educational, and other construction development. We serve California, Washington State, Oregon, Colorado and Nevada. We are proud to announce that a project The Conco Companies provided concrete services for has won another award. The LA Federal Courthouse in downtown LA was recently recognized as a “Gold Winner” in the category for Best Sustainable Project by the LA Business Journal‘s Commercial Real Estate Awards. Last year the Courthouse also won the “2016 Outstanding Achievement and Excellence in Concrete Construction” award presented by the Southern California ACI chapter. In addition the project was selected to compete at the national level at the 2017 ACI National Convention.
Referred to as the “Cube” for its unique cantilevered shape, the 631,000 sq. ft. courthouse was designed and built to earn LEED Platinum certification. The general contractor on the $350 million project was Clark Construction and the architect was Skidmore, Owings & Merrill (SOM). The building’s high efficiency systems include a 1,200-ton central utility plant with a 130-ton heat recovery chiller. It also features a 250 KW roof-mounted photovoltaic array of solar panels. A large skylight brings in natural light and the building’s exterior has “pleats” that maximize daylight penetration and minimizes solar thermal gains. The building’s innovative design allows the cubic volume to “float” over the stone base and is considered to be one of the safest structures against bomb threats or earthquakes. The 10-story Courthouse sits on a 3.6-acre site and includes 24 courtrooms and 32 chambers for judges along with jury assembly facilities and offices for U.S. Marshals. SOM describes the Courthouse design as “using traditional architectural elements such as processional steps, grand public spaces, and enduring materials like limestone to achieve a strong civic identity.” The project broke ground in 2013 and judges and staff started moving into their new offices in September, 2016. 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. At The Conco Companies, we have experience placing any type of concrete for a broad range of projects and in a variety of weather conditions. Our crews use several different methods for curing concrete as it is determined by the type of construction and the concrete mix as well as outside temperatures and humidity. Other considerations include project specifications and/or parameters of the jobsite. However regardless of the technique used for curing, it is important to keep the concrete moist and prevent further loss of moisture.
The Portland Cement Association explains that the purpose of curing is to provide the “adequate amount of moisture for continued hydration and development of strength, volume stability, resistance to freezing and thawing, and abrasion and scaling resistance.” When we control the rate and amount of moisture the concrete loses during cement hydration, it is allowed to achieve its optimal strength and durability. Curing is done at the jobsite once the concrete is placed and finished, or during the manufacturing of concrete products. While curing may only take a few days, the concrete requires a number of days or in some cases weeks or months to attain its full strength and durability. Preventing the loss of moisture during curing is done in a number of ways. One method leaves the formwork in place and/or covers the concrete with an impervious paper, plastic sheeting or a membrane-forming compound. Another includes spraying (or fogging), ponding or using wet coverings to cool the concrete as the water evaporates. The American Concrete Institute (ACI) recommends a curing period of a minimum of 7 days or until 70% of the specified compressive strength is achieved for most concrete structures in temperatures 40º F and above. If desired an accelerant can be used to speed up the hardening process and reduce the curing period to only 3 days if temperatures are above 50º F. Other variables are determined by the size and shape of the structure and strength requirements as well as the type of weather conditions the concrete will be exposed to during its life-cycle. The Conco Companies 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 providing services for commercial, educational, parking and other construction development as well as public works projects. We serve California, Washington State, Oregon, Colorado and Nevada. Source: cement.org/for-concrete-books-learning/concrete-technology/concrete-construction/curing-in-construction, concrete.org/TopicsinConcrete/TopicDetail.aspx?id=25&Search=Curing Concrete spalling and cracking, sometime referred to as concrete cancer, is caused by rebar corrosion and can affect buildings and other concrete structures. Once the steel reinforcing in a concrete slab begins to rust, the steel rust can expand up to 7 times its original size and results in concrete being displaced and getting flakey. As the steel pushes the concrete away, it allows more water to come into contact with the steel and compounds the problem.
Visible rust stains on the outside of the concrete or leaking, bubbling up stains from within the concrete are probably all signs of concrete spalling and can be a dangerous. The spalling can cause chucks of concrete to separate from a building or bridge and becomes a real hazard to any pedestrians or traffic passing by below. The good news is that a group of researchers at the University of British Columbia in Canada may have found a cure for concrete cancer. According to their study, they have gotten good results with producing concrete using discarded glass. The researchers report that “by partially replacing cement with polymer, fly ash and glass powder, we were able to produce concrete that was more than 60% stronger than what was previously believed possible.” They are looking to further test their products but hope to eventually replace up to 25% of traditional cement materials, mined from the earth with recycled glass. One of the authors of the report, Shahria Alam, an associate professor of engineering at the University, explains that millions of tons of glass bypass recycling centers and end up in North American landfills. Their goal was to make smarter and “greener” building materials without having to take new resources out of the ground. 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 providing services for commercial, educational, parking and other construction development as well as public works projects. We serve California, Washington State, Oregon, Colorado and Nevada. Source: remedial.com.au/structural-repairs/concrete-cancer Fiber reinforced concrete (FRC), a type of reinforced concrete that uses a fibrous substance to increase structural strength, durability and ductility, is a subject of new research and developments. In FRC, short, discrete fibers are uniformly distributed and randomly oriented to provide a kind of three-dimensional stability and include fibers made of steel, glass and synthetic or natural material. Depending on which material is used, they offer varying properties and characteristics.
For example steel fibers can increase the structural strength of concrete and reduce the steel reinforcement requirements as well as crack widths for better durability. Also the addition of steel fibers to a concrete mix can improve impact along with abrasion-resistance and freeze-thaw resistance. Using polypropylene or nylon fibers in concrete can improve the mix cohesion and freeze/ thaw resistance and make concrete easier to pump long distances. Furthermore, the fibers provide an increased resistance to plastic shrinkage during curing and improve the structural strength and ductility. As with steel fibers, polypropylene and nylon fibers reduce the steel reinforcement requirements. Sometimes a construction project will use both steel and polymeric fibers to get the benefit of structural strength provided by steel fibers and the “resistance to explosive spalling and plastic shrinkage improvements provided by polymeric fibers.” After testing to ensure minimum requirements are met, some precast applications and industrial flooring use steel or synthetic fibers in place of rebar in reinforced concrete. While fiber reinforced concrete has been around for centuries such as horsehair in mortar, straw in mudbricks, and the use of asbestos fibers during the 1900s, there are new developments and innovations in FRC. One example is High-performance Fiber Reinforced Concrete (HPFRC), which researchers claim to be 500 times more resistance to cracking and 40 percent lighter than traditional concrete. More research is being done to validate the claims. Another recent study used carpet waste fibers in concrete as a way to environmentally recycle carpet. Also a new trend that completely changes our view of concrete as an opaque mass is to add optical fibers to the mix to create a translucent concrete. 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 providing services for commercial, educational, parking and other construction development as well as public works projects. We serve California, Washington State, Oregon, Colorado and Nevada. Source: en.wikipedia.org/wiki/Fiber-reinforced_concrete At The Conco Companies, we make it a point to stay up-to-date on the latest concrete news and innovations, and implement new ideas and technologies designed to save our customers time and money as well as to create a better finished product. Some emerging trends in concrete that are changing concrete design and construction include high strength / high performance concrete (HSC/HPC); self-consolidating concrete (SCC); fiber reinforced concrete (FRC) polymer modified concrete (PMC); high volume flyash concrete (HVFC); reactive powder concrete (RPC); and self-healing concrete / bacterial concrete.
Innovations in precast concrete, which is produced by casting concrete in a reusable mold or "form" and cured in a controlled environment before being transported to the jobsite include the manufacturing of ultralite panels using Carbon Cast. This precast concrete technology uses carbon-fiber grid reinforcing to create panels that weigh less and result in reduced shipping, erection and substructure costs. The Portland Cement Association cites the new P.O.S.T. (Prestressed Open Space Truss) as providing a “solution for long-spans, while maintaining the shallow floor depth of a flat plate system.” They say the system works well for hotel and condominium applications, especially for those constructed with lower level parking. The National Ready Mix Concrete Association states that self-consolidating concrete is another time and labor saver as it “pumps easier, fills complex shapes, produces pristine finishes and encapsulates congested reinforcement.” They explain that the two important properties specific to SCC in its plastic state are its flowability and stability. This is typically accomplished by using high-range water-reducing admixtures, not by adding more water. Insulated Concrete Form (ICF) walls are also increasingly becoming a popular option in residential and commercial markets and offer the advantage of fast construction, energy savings and increased durability. The walls provide occupants not only a quieter environment but a safer one as studies show improved “results for resistance to catastrophic loadings, including fire, wind, and tornados.” Conco’s mission is to be the best supplier of concrete services in the Western United States and to bring expertise, experience and quality to each project. We continue to upgrade and expand facilities to better serve the growing market for public works projects, commercial, parking structures, educational, and other construction development. We serve California, Washington State, Oregon, Colorado and Nevada. Sources: slideshare.net/sabnisajit/an-overview-of-emerging-trends-in-construction-technologies cement.org/designaids/emerging-trends Slump is the measure of the consistency in a specific batch of fresh concrete. A slump test accesses the consistency of the fresh concrete, and to ensure that the correct amount of water has been added to the mix.
To conduct the test, an Abrams slump cone is used, a bottomless, 12” high circular cone with an 8” in diameter base and a 4” in diameter top. The cone is placed on a level, impermeable surface and filled in three stages with equal amounts of concrete. Each layer is tamped down using a special rod to make sure the concrete is compacted and leveled off with the top of the cone. The cone is then carefully removed and the concrete is left to settle or “slump.” The slump cone is placed alongside the pile of concrete in order to measure the height of the concrete in comparison to the top of the cone. Measurements are taken to the nearest 5mm. Wikipedia states, “The slumped concrete takes various shapes, and according to the profile of slumped concrete, the slump is termed as true slump, shear slump or collapse slump.” If the concrete simply subsides but generally maintains its shape, it is considered to be a true slump. In the case of a shear slump, the top portion of the concrete shears off. If the test results in a “collapse slump”, it typically indicates the mix is too wet; or it may be a high workability mix that needs to have a flow test done rather than a slump test. Up until just a few decades ago, concrete was made from portland cement, aggregate and water. In this type of concrete mix, the coarse aggregate dictated the water content, and concrete with a lower slump value contained less water and resulted in a better quality of concrete. Today much of the concrete we produce is a blend of not only cement and aggregate but admixtures, fibers and polymers. This means the aggregate is not the only thing that influences the amount of water added and other factors have to be considered to determine the proper consistency of the concrete. 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 providing services for commercial, educational, parking and other construction development as well as public works projects. We serve California, Washington State, Oregon, Colorado and Nevada. Sources: concrete.org.uk/fingertips_nuggets.asp?cmd=display&id=559 en.wikipedia.org/wiki/Concrete_slump_test Insulating Concrete Form (ICF) systems are being used in everything from single story buildings to 20+ story high-rises. Common types of projects include single and multifamily residential housing, hotels, offices, educational and healthcare facilities, manufacturing and warehouse buildings and others.
ICF construction offers several benefits including energy efficiency, diaster resiliancy, noise reduction, strength and durability, and sustainability. In addition it is competitively priced in comparison to steel frame, wood frame, and masonry construction. Buildings constructed with ICFs are also very fire resistent, and in multi-family housing, can help to isolate the fire to a single unit and protect both lives and property. The system works a lot like LEGOs as it is comprised of interlocking blocks with mechanisms that connect together. Each block is made out of molded expanded polystyrene (EPS) insulation in a variety of sizes. According to an article from Concrete INFOCUS, “the most common configuration of an ICF unit is made of two layers of 2-1/2 to 2-5/8 inch thick EPS spaced 4, 6, 8, 10, or 12 inches apart for most low to mid-rise buildings.” In the case of taller buildings or when the project consists of high ceilings or large loadings, the structure requires thicker walls. ICF blocks are identifyied by the width of the cavity and wider units include 6-inch, 8-inch and larger. Typically blocks are fully assembled at the manufacturing site although some blocks are folded into a flat configuration and shipped, while other manufacturers produce ICF forms that are assembled at the jobsite. After the ICF blocks are installed, concrete is pumped into the cavity to make a strong, uniformly-thick concrete wall. Concrete INFOCUS says the “recommended maximum aggregate size should be 1/2- inch aggregate for 4- and 6-inch cavity forms and ¾-inch aggregate for 8-inch and larger cavity forms.” 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. Source: nxtbook.com/naylor/NRCQ/NRCQ0117/index.php#/20 At The Conco Companies we have years of experience placing concrete in all kinds of weather conditions. We are often asked if it is ever too cold or too hot to safely place concrete. The answer is not necessarily a “yes” or “no” but rather other factors are taken into consideration.
In terms of cold temperature, normal concrete mixes will not properly set or harden when the concrete temperature is below approximately 35° F. However by making some changes to the mix such as adding heated water and aggregates or the addition of accelerating admixtures, concrete can be placed at below freezing temperatures but it is more expensive. Since most of the West Coast (Conco’s primary service areas) does not experience more than occasional episodes of below freezing temperatures, it is generally easier to wait for a warmer day. In extreme heat of 90° F and above, concrete not only starts to set and harden faster but it can cause a reduction in the ultimate strength of the concrete. Plastic shrinkage and drying shrinkage can also be a problem in very windy or low humidity conditions. To mitigate these problems, the timing of placement along with the addition of retarding admixtures and proper curing are implemented. On the historic continuous mat pour we did a few years ago for the Wilshire Grand Tower in Los Angeles, we needed to make provisions for the heat generated in mat foundations. In mass concrete structures there are two thermal properties that must be considered: the maximum temperature and the temperature difference between the center of the structure and surface. With help from a team of experts, we developed a thermal control plan specific to the mix design, the geometry of the foundation and the configuration of the rebar. The fix involved mechanically controlling the temperature by post-chilling the concrete with cooling pipes to remove the heat. We successfully kept the maximum temperature below ACI limits and a temperature difference that was well within the ranges required to avoid thermal cracking. 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. |
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