Stricter Requirements for ACPA Operators

According to the American Concrete Pumping Association (ACPA), there is a heightened awareness of ACPA certification, and as such, it has increased the demand for certified pump operators. The ACPA states that, “certification has proven to raise the safety awareness of operators, which can help eliminate the risk of harm when using a concrete pump on the job site.”  Last year, the Association saw a 20% growth in their certification training program.  They trained a record number of operators despite an estimated loss of 1,000 pumps in the industry since 2006.

The program now includes a mandatory ACPA Safety Presentation Program and there have been modifications made to the certification test regarding security and authenticity.  Furthermore, when you choose to use an ACPA certified operator at your job site, you are in compliance with the personnel requirements of the ASME B30.27 Safety Standard for Material Placement Systems.  

Another part of the recently introduced ASME B30.27 includes pump operators performing an “operation test demonstrating proficiency in handling the specific type material placement system, including both pre-start and post-start inspection, setup procedures, maneuvering skills, shutdown and securing procedures.”  The ACPA is still looking at how this type of extensive testing should be handled and by whom. 

At The Conco Companies, every one of our concrete pump operators are ACPA certified and are trained to operate equipment safely and to protect those who work around the pump from harm.  In addition to ACPA certification and company specific safety training, Conco obtains inspections of all of our boom pumps and Telebelts every year by certified boom pump inspectors.  This ensures the structural integrity of the equipment we operate.  Conco has developed and implemented some of the most rigorous pumping safety procedures in the entire concrete industry.

The Conco Companies are 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 four regional offices, we serve California, Oregon, Washington, Nevada and Colorado.  

 Sources: mydigimag.rrd.com/publication/?i=253083

The Slump Test is Used to Determine Consistency of Concrete

Until several decades ago, concrete primarily contained portland cement, aggregate and water.  This allowed the coarse aggregate to dictate the water content, and the amount of water in the concrete to determine the slump.  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.  Now other factors are considered to determine the proper consistency.

So what is slump?  It is defined as the measure of the consistency of a specific batch of fresh concrete.  To determine the slump, a simple test is done that measures the amount of water added to the mix.  The test is done using an Abrams slump cone, which is a bottomless, 12” high circular cone with a base 8” in diameter and a top 4” in diameter.

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.”  Placing the cone alongside the pile of concrete, the height of the concrete is compared to the top of the slump cone and measured 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.”  

A true slump is where the concrete simply subsides but generally maintains its shape, whereas in a shear slump, the top portion of the concrete shears off.  A collapse slump generally means the mix is too wet, or it may be a case of a high workability mix that needs to have a flow test done rather than a slump test. 

Conco is a leading supplier of concrete services for the Western United States. We have built our reputation by offering superior concrete formwork, reinforcing, place and finish, shotcrete and other ancillary services that benefit from our vast experience.  The Conco Companies have four regional offices to serve California, Oregon, Washington, Nevada and Colorado.

 Source: concrete.org.uk/fingertips_nuggets.asp?cmd=display&id=559

en.wikipedia.org/wiki/Concrete_slump_test

The Great Pyramid of Giza – An Architectural Wonder

The Conco Companies have been busy working on modern day wonders such as when we set the world record for the largest continuous mat pour on the new Wilshire Grand in L.A.  The building is slated to become the tallest building west of the Mississippi.   To reach the upper levels of the tower, we are using a new state-of-the art electric pump to pump concrete 400 ft. horizontally and then 1,000 ft.   Another large project we are working on is the Salesforce Tower in downtown San Francisco, which will become the second tallest building in the western U.S. 

Today modern architecture is still influenced by what is known as the Seven Wonders of the Ancient World.  Of these man-made structures, the Colossus of Rhodes, the Lighthouse of Alexandria and the Mausoleum at Halicarnassus were destroyed in earthquakes.  The Temple of Artemis and the Statue of Zeus were deliberately destroyed and the location of the Hanging Gardens is unknown or may not have really ever existed.  This brings us to the Great Pyramid of Giza, which is not only the oldest of the Seven Wonders but is the only one mainly intact.  It was the tallest man-made structure in the world for over 3,800 years until the 520 ft. spire of the Lincoln Cathedral was completed in the 1300’s.

The Great Pyramid was built using an estimated 5.5 million tons of limestone, 8,000 tons of granite and 500,000 tons of mortar.  The surface of the pyramid consisted of casing stones, which are slant-faced, flat topped blocks.  They were made of Tura limestone and brought across the Nile River.  Most of the casing stones were loosened in an earthquake in the 1300’s and were later used to build mosques and fortresses in Cairo.  The huge granite stones in the “King’s” chamber were transported from Aswan, 500 miles away, and weighed 25 to 80 tons a piece. 

Built sometime around 2584–2561 BC, there has been much speculation throughout the years of how the Great Pyramid was built.  While the Greeks thought slave labor was used, modern studies point to tens of thousands of skilled workers doing the job.  In a study conducted by Mark Lehner and other Egyptologists, they estimate that the construction of the pyramid took around 10 years and required “an average workforce of 14, 567 people and a peak workforce of 40,000. 

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 extensive experience includes commercial, educational, parking and other construction development as well as public works projects.  We currently serve California, Washington State, Oregon, Colorado and Nevada.

 Source:  en.wikipedia.org/wiki/Great_Pyramid_of_Giza

Hot Weather Concreting

Now that summer is here and more construction projects are getting underway, one consideration concrete contractors take into account is how higher temperatures and dry, windy conditions affect mixing, placing and curing concrete.  The American Concrete Institute (ACI) defines hot weather concreting as “one or a combination of the following conditions that tends to impair the quality of freshly mixed or hardened concrete by accelerating the rate of moisture loss and rate of cement hydration, or otherwise causing detrimental results: high ambient temperature; high concrete temperature; low relative humidity; and high wind speed.”   

Laboratory tests have shown that while concrete mixed, placed and cured during elevated temperatures develops higher early strengths, it can result in improper curing.  Also plastic shrinkage, which is the result of the loss of water from the surface of the concrete, is accelerated in hot temperatures, windy conditions and/or in low humidity.  When humidity is above 80%, plastic shrinkage is generally not a problem even in higher temperatures.    

One of the things that can occur when mixing and placing concrete in windy or hot conditions is the need for more water in the mix.  As the concrete may exhibit an increased rate of slump loss, the tendency is to add more water at the job site.  In addition there is the increased risk of plastic shrinkage and thermal cracking.  Another problem is it becomes harder to control the entrained air content of the concrete.  Furthermore, the increased rate of setting can make concrete more difficult to handle, compact, and finish and creates an environment that can result in a higher risk of cold joints.  

At The Conco Companies, our vast experience has given us the opportunity to place concrete under a number of climate conditions and specialized placement options.  Along with our highly trained, professional staff, we utilize the most leading-edge technology and equipment to offer customers the best quality results.

With Conco’s state-of-the-art concrete pumps and innovative methods we can handle the toughest challenges.   All of our highly trained pump operators are ACPA certified and our pumping division maintains an outstanding safety record. We understand the trust customers place in us once they choose our services, which is why we approach each project as a partnership from concept right through to completion.

Source: concrete.org/news/newsdetail.aspx?f=51687868