One of the big projects The Conco Companies recently provided a full range of concrete services for was the Salesforce Tower in downtown San Francisco. Now that the silvery curtain-wall panels have completely covered the outside of the 1,070-foot tall building, it can be seen for miles in and around San Francisco. This is probably not surprising as the peak of the building stands 200 feet taller than the city’s previously tallest building, the Transamerica Pyramid. The 61-story building consists of 900 feet of occupied space with spacious office floors that boast ceiling heights of almost 14 feet. The remaining 170 feet above the top floor of the building is mainly empty space but does house some mechanical equipment.
To get a feel for the size and beauty of the mostly completed building, visit the Salesforce Tower’s facebook page to see several newly posted videos and pictures. One interesting video from September 15th includes a conversation between the project’s developers, Executive Chairman of Boston Properties, Mortimer Zuckerman, and Gregory Hines, the Founder and Chairman of Hines. They discuss how the Salesforce Tower is destined to become the iconic San Francisco building and how the architect, César Pelli has created a building that is beautiful to look at on the outside and works wonderfully on the inside. There are also a couple of spectacular pictures of lightening striking the Tower during a recent storm in the Bay Area that the National Weather Service reported produced over 800 lightning strikes. Another picture is from the 34th floor of the building and provides an impressive view of the Bay Bridge. You will also find a picture of the solar ellipse alongside the skyscraper. Please visit The Conco Companies website to see a portfolio of many of the other remarkable projects we have had the honor to be a part. We pride ourselves on delivering quality work and have the reputation of bringing projects in on time and on budget. 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. Our concrete services include commercial, educational, parking and other construction development as well as public works projects and highways.
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The Council on Tall Buildings and Urban Habitat (CTBUH) recently published a report in collaboration with the Guinness Book of World Records on the fastest elevators and the longest elevator run in skyscrapers. It evaluates elevators in commercial buildings from across the globe to determine the speed and the length of their run. The CTBUH has certified the Shanghai Tower, currently the world's second-tallest building at 632 meters tall (2,073′), takes the prize for both the “fastest elevator and the longest elevator run of all commercial buildings in the world.”
The Shanghai’s elevator has a speed of 20.5 meters per second and an elevator run of 578.55 meters (1898.13). The world’s second fastest elevator speed is in the CTF Finance Center in Guangzhou coming in at 20 meters per second followed by the Tapei 101 at 508 meters tall with a speed of 16.83 meters per second. The Ping An Finance Centre has the world’s second longest elevator run of 573.5 meters which is followed by the CTF Finance Center with a run of 516.7 meters. The Burj Khalifa has an elevator run of 504 meters. Out of the world’s five tallest buildings, four of them tie (the Burj Khalifa, Shanghai Tower, Ping An Finance, and Lotte World Tower) for the fastest double-decker elevator speeds of 10 meters per second. Here in the US, New York’s One World Trade Center has an elevator run of 1341 feet that goes deep into its basement. The Conco Companies have an extensive portfolio that includes providing concrete services on two of the West Coast’s tallest skyscrapers, the Wilshire Grand Center in Los Angeles and the Salesforce Tower in San Francisco. Please visit our website to view the many projects we have featured and contact us to see how we may assist you on your next project. The Conco Companies are a leading supplier of concrete services for the Western United States. Our experience includes constructing commercial, educational, healthcare, parking structures and other development as well as public works projects and highways. We currently serve the areas of Southern and Northern California, Oregon, Washington, Nevada and Colorado. Source:ctbuh.org/Publications/CTBUHJournal/InNumbers/VerticalTransportationAscentAcceleration/tabid/7633/language/en-US/Default.aspx During our close to 60 years in the industry, The Conco Companies have learned a thing or two about the construction business. Right from the start, our goal has been to provide customers with first-class services that are executed in a highly professional manner and to deliver what was promised.
On our website, you will find detailed information regarding our extensive concrete services and locations as well as profiles of many of the various projects we have had a role in. The website also provides customers with some useful information in our Whitepaper titled, “Hiring the Best Commercial Subcontractor,” that is available for download. The document explores a number of considerations that should be taken into account before a commercial general contractor on a large project hires a commercial subcontractor. While the decision may be influenced by a number of factors including the level of involvement of the project developer and the specifications of the project, one important consideration should be whether or not the subcontractor is capably of consistently meeting the project goals and needs. Furthermore, the best choice may not necessarily be a firm the G.C. has a prior relationship with, but should be based on the company’s ability to perform the job in a timely fashion in order to produce the best final product. Our Whitepaper offers insight in ways to evaluate the subcontractor’s management team and expertise beyond just looking at their past projects. We discuss the reasons why industry trade activities and credentials are important and the best ways to engage the team right from the project’s conception. In addition you will find other tips to help you hire the best team for your project. Please visit our website to download a copy of our Hiring the Best Commercial Subcontractor, and contact us to see how we can provide your next project with a broad range of excellent concrete services. 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. Most material, including concrete, shrinks as it dries. The Portland Cement Association (PCA) points out that the most common amount of shrinkage is about 1/16 of an inch in a 10-foot length of concrete. To alleviate the problem, joints are placed in concrete pavement and floors “to allow the concrete to crack in a neat, straight line at the joint, where concrete cracks due to shrinkage are expected to occur.” Likewise expansion joints are placed in bridges, concrete walls and other structures to allow for shrinkage and to control cracking.
To help move and place concrete efficiently, concrete specialists add more water to the mix than what is strictly necessary to hydrate the cement materials. Once the concrete is placed, the excess water begins to separate from the hardening concrete, which results in a loss of volume that causes the concrete to shrink. As the concrete’s reinforcement or base friction works to restrain it, the tensile stresses in the slab cause the cracks. Since shrinking is one of the inherent properties of concrete, it is impossible to totally eliminate cracking but it can be controlled. This is the job of concrete contractors and engineers who strive to understand and address the volume change that takes place in the concrete in order to reduce the amount of shrinkage. The PCA explains that, “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 help solve the shrinkage problem, contractors take care to use the proper concrete mix design that will require the least amount of water as well as use the largest size of aggregate appropriate to the job. Contractors especially watch for fluctuating temperatures during the first 24 hours after the concrete is placed. The Conco Companies are a leading supplier of concrete services for the Western U.S. and 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. Our offices serve California, Colorado, Oregon, Washington and Nevada. Sources: concretenetwork.com/concrete/concrete_cracks/preventing_concrete_cracks.htm cement.org/cement-concrete-applications/cement-and-concrete-basics-faqs/lists/technical-information/concrete-cracking Over the last several decades, technological advancements in the concrete industry have led to improvements in both the strength of concrete as well as the longevity. In fact, experts predict that concrete mixes of today can produce concrete that will last for hundreds of years rather than just decades of concrete structures from the 20th century. Along with the superior performance, concrete has also become “greener” to produce.
With new materials being used in the production process, changes in the mixture’s proportions, and increased recycling efforts, concrete’s environmental impact has been reduced and durability improved. AggregateResearch.com states that, “new concretes have better corrosion resistance, equal or higher compressive and tensile strengths, higher fire resistance, and rapid curing and strength gain. In addition, the production and life cycle of these new concretes will reduce greenhouse gas emissions by as much as 90%.” High Performance Concrete (HPC), Ultra-High Performance Concrete (UHPC), and geopolymer concrete are new types of concrete mixtures that offer several advantages over traditional concrete with few disadvantages. For example HPC and UHPC are produced using industrial waste by-products such as fly ash, blast furnace slag, and silica fume. The addition of these by-products reduces the amount of portland cement required in the mix, which in turn, cuts down on the amount of carbon dioxide emitted during the production of the cement. Also there are an abundance of the by-products and are typically less expensive than portland cement. Other advancements in the industry include producing fiber reinforced concrete, which is premixed with dry components to create higher tensile and flexural strengths than found in standard concrete. Fiber reinforcement can be done with steel fibers, glass fibers, synthetic fibers and natural fibers and is less expensive than hand tied rebar. The Conco Companies are a leading supplier of concrete services for the Western U.S. and 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. Our offices serve California, Colorado, Oregon, Washington and Nevada. Sources:aggregateresearch.com/articles/19247/Advances-in-new-concrete-technology.aspx Portland cement is the most common type of cement and typically originates from limestone. It is the key ingredient in concrete, mortar and stucco and used throughout the world. When added to concrete, it is the paste that binds the aggregate (consisting of gravel and sand) with the water.
Defined as hydraulic cement (cement that not only hardens by reacting with water but also forms a water-resistant product), it is “produced by pulverizing clinkers consisting of essentially hydraulic calcium silicates, usually containing one or more of the forms of calcium sulfate as an inter ground addition.” The concrete mix’s strength depends on the reaction of the calcium silicates with the water. The Portland Cement Association explains that, “Cement is manufactured through a closely controlled chemical combination of calcium, silicon, aluminum, iron and other ingredients.” To produce portland cement, raw materials such as limestone, shell, or chalk are combined with clay, silica sand, shale, bauxite, fly ash, slag and iron. This mixture is heated in huge cement kilns at temperatures as high as 2,700 degrees Fahrenheit. A dark grey nodular about the size of a marble called a clinker is produced from the extreme heat and is ground into a fine powder to make the cement. Once it has cooled, a small amount of gypsum may also be added to control the setting process. Portland cement is thought to be the invention of Joseph Aspdin, a bricklayer from England, and named for its similarity to a common building stone found on the Isle of Portland in Dorset, England. Aspdin experiments were conducted in his kitchen stove where he fired ground limestone and clay together to create the first artificial cement. His new cement was a much stronger material than the standard unfired crushed limestone used during that period of time. 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. Sources: en.wikipedia.org/wiki/Portland_cement, cement.org/cement-concrete-basics/how-cement-is-made One of the mysteries that continue to baffle scientists and engineers is how the ancient Romans produced the strongest concrete in the world. Typically modern concrete buildings last about 50 to 60 years while ancient Roman concrete structures have survived through 2,000 years of environmental damage.
We know that the formula used to produce the ancient concrete is unique but no one knows for sure why it is so durable, but a group of scientists thinks they may soon find some answers. Geologists and biologists will travel to the Surtsey Island in Iceland to see if they are right. Since ancient Roman concrete was made from volcanic ash and seawater, Surtsey is a good place for answers as the entire island is made of volcanic ash and seawater caused by an underwater volcanic eruption in 1963. In 1979, researchers drilled a hole 181 meters (593 feet) deep into the volcanic rock in order to study the microbial life. The hole has been monitored since it was drilled and temperatures have cooled from 140 °C to about 130 °C. On their upcoming trip they plan to drill two more holes, one that is parallel to the original hole and another at an angle. The new holes will be deeper that the one from 1979 and is expected to penetrate 190 meters (623 feet) down to the original ocean floor before the eruption. The scientists plan to study the rock and mineral formation of the volcano and try to determine what makes the volcanic material so durable. Researchers explain that Surtsey is “unique because when it formed the mixture of heat, volcanic material, and seawater created hydrothermal minerals that strengthened the rock.” The island is much more durable than other volcanic islands as the volcanic rock is less porous and almost impervious to erosion. The hope is that by analyzing the rock from Surtsey, it may provide clues to the volcanic ash that went into ancient Roman concrete. 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:concreteconstruction.net/business/scientists-hope-this-volcanic-island-holds-the-answer-to-stronger-concrete_c As one of the leading commercial concrete contractors in the nation, The Conco Companies provide the Western United States with a wide range of concrete services including producing and placing cellular concrete. Also known as foam concrete, cellular concrete provides customers with one of the most productive, cost-effective solutions in a variety of applications.
Our proprietary cellular concrete product is Confoam™, and is a lightweight, low-density fill material that we customize for each specific job. In addition we have the specialized production equipment and experienced crews that know how to expertly place the highly flowable material for optimal results. While lightweight concrete is typically a concrete made with aggregates lighter than typical stone aggregates and has a density + 120 lb. / cu.ft., cellular concrete uses the internal air cell structure instead of an aggregate and exhibits densities from 20 to 90 lb. / cu. ft. Our cement-based slurry contains a high percentage of foam entrained into the plastic mortar and offers a perfect solution for filling challenging voids underneath slabs and tight, unstable trenches. Also Confoam has a fairly low carbon footprint that makes it “greener” than traditional concretes. Another advantage of using Conco’s foam concrete is that it is self-compacting, and thus eliminates the need for mechanical compaction, which means there is no impact on retaining structures or deep foundations. Furthermore, cellular concrete can be produced to be lighter in weight than the site’s compacted base materials or native soils, and as such, provides an inexpensive solution for foundations. This also means there is virtually no settlement as Confoam can be produced to make the combined weight of the new structure less than or equal to the weight of the removed soil. And perhaps most importantly, placing cellular concrete is safer than traditional fill methods as it does not require employees to be placed in the excavation area. Cellular concrete is just one solution The Conco Companies offer customers to help save time and money. Please visit our website or contact us to learn more about how we can help to get your next project off to a great start. 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. 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 |
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