Hanson Structural Precast

Transcription

1 Form+Function NEWS & INFORMATION FROM HAMILTON FORM WINTER 2015 Project Profile Minnesota Vikings Stadium Hanson Structural Precast T Vikings Stadium, designed by HKS Architects. he new Minnesota Vikings Stadium broke ground in December of The Metrodome, home to the Minnesota Vikings since 1982, was razed to make room for the new stadium, marking the end of another old, iconic NFL stadium. The Metrodome, built in 1980, was constructed using precast triple risers from the Hanson Structural Precast plant in Maple Grove, MN. It had a domed roof that was held in place with pressurized air. Fans entered the stadium through revolving doors to help keep the air pressurized inside the stadium. This multi-purpose domed stadium was unique because it was the only venue to host a Major League All Star Game, a Super Bowl, a NCAA Men s Final Four and a World Series. But, the old 900,000 square foot facility is giving way to a new 1,750,000 square foot stadium that has already secured the Super Bowl in 2018 and the NCAA Men s Final Four in The new Vikings Stadium was designed by HKS, the Dallas firm that designed Lucas Oil Field in Indianapolis and the AT&T Stadium in Arlington, Texas. It will feature high-tech glass walls, a trellis-like glass roof, and 95-foot-tall pivoting glass entry doors. The stadium offers an expanded range of premium seating including suites, club seats and seven premium club lounges. Breaking the trend of retractable roofs, the new Vikings Stadium will have a fixed roof made of translucent glass, providing an outdoor feel while providing protection from the elements. Hanson Structural Precast, now part of Wells Concrete, won the precast concrete contract for the project. Although the original design called for double and triple risers, Hanson won the contract by converting the project to single risers, which it had used on Target Field, the new Minnesota Twins Stadium and the University of Minnesota Gophers football stadium. (continued) Hamilton Form delivered single tier stadia risers for the new Vikings Stadium scheduled to open for the 2016 NFL season.

2 Project Profile Minnesota Vikings Stadium (continued) Hanson Structural Precast The single risers are cast upside down to improve the quality and consistency of the finish. Single risers also allow for better quality control of the joining of sections. The risers are being efficiently erected using a vacuum lift system. In addition to the more than 102,000 linear feet of risers, Hanson Structural Precast is also supplying precast concrete beams, columns, raker beams, spandrels, stairs and wall units for the project. The new 65,400 capacity Minnesota Vikings stadium, built on the site of the old Metrodome, is scheduled to open for the 2016 NFL season. Hanson is erecting the risers using a vacuum lift. Adjustable Stair Package This adjustable stair form was designed to cast eight different product configurations. The products were mirrored with the hand rail moving from left to right. Bolt-on fillers were provided that could be moved from side to side. In addition, the width and depth of the landings could be changed by adjusting the positioning of the side rails. Stair form drawings show fillers in use and the base form with bolting locations for various headers, fillers and block outs.

3 Formwork Taking on Stairs W hen a project calls for precast stairs, it can be difficult to determine if the purchase of a custom steel form is warranted or if a wood form built in-house will do the trick. Whether the form is made by your carpenter shop or by your form supplier, a stair form is a labor intense form to build. Typically, a single, repetitive product lends itself to purchasing a custom steel form. However, with some imagination and planning, a single form can cast several products with simple adjustments. That was the case when Hamilton Form made a set of stair forms for Molin Concrete products in Lino Lakes, Minnesota for the Community Facility at the University of Nebraska in Omaha. The first form was designed to cast a single, higher volume product. The product was cast upside down and consisted of nine treads. The base form was approximately 12 long by 7-4 wide. One side of the form was fixed, but for future considerations, a bolt down side form was used on the other side so a narrower product could be cast if needed. The second form was approximately 18-6 long by 12 wide. This product had 4 treads with integral top and bottom landings. The width and depth of both landings could be changed by changing the positioning of the rails. Block outs were supplied to change the width of the treads. In addition, two separate block out pieces were supplied that could be moved from left to right for positioning the hand rail and stair well from side to side. The form cast eight different product configurations. The adjustable package included a base form, adjustable upper and lower side forms, a back pan that fits over the top of the base form, and seventeen different block outs, fillers and adjustable headers. The pieces fit together like a puzzle and provided a productive, easy to use solution to a complicated project.

4 Technically Speaking Concrete Curing in Cold Weather A s seasons change, we adapt; clothes, outdoor activities, and for precasters, plant processes. Cold weather procedures may include changes in mix design, placing, finishing and curing concrete. Concrete gains strength as it cures. Proper curing has a strong influence on the durability, strength and the quality of concrete. When temperatures change the temperature of the concrete when it s placed in the form and the ambient temperature, while the concrete is curing, should be monitored. According to ACI 306R-10 Guide to Cold Weather Concreting; The temperature of the concrete directly influences the rate of setting and strength gain. Concrete has a slower rate of reaction when the concrete mix and the ambient temperature are lower. How low are low temperatures? When ambient temperatures fall or are expected to fall below 40 degrees F; it s time to take cold weather precautions. HUMIDITY Curing is the process of slowing evaporation and maintaining a desirable temperature in the concrete to promote hydration. To properly cure, the relative humidity of the concrete should be kept at least 80%. Depending on your mix, most concrete has enough water in it to promote hydration. However, if evaporation takes place too quickly, the rate of hydration will slow or even prevent adequate hydration for curing. TEMPERATURE Hydration progresses slower when the temperature of the concrete is lower. At 40 degrees F, development is greatly retarded; and, at the freezing point, little or no strength develops. Therefore, special considerations should be made for curing concrete in cold winter months, especially if production is outdoors. In cold weather, anticipate delays in reaching the design strength of the concrete. Also, rapid temperature differentials can crack and damage the concrete. ACI recommends you Don t thermal shock the concrete. Heating and cooling concrete too quickly can lead to cracks. COVERINGS One of the simplest ways to hold moisture and heat in concrete is to cover it with an insulated curing blanket. Concrete generates its own heat. An insulated concrete curing blanket holds heat and moisture in the concrete, slowing its release to aid the curing process. CONTROLLED HEATING Another option to control the hydration process is with the installation of a controlled heating system. Increasing heat will help concrete cure faster. An 18 degree temperature increase almost doubles the rate of hydration, and that may make installation of a controlled curing system a good investment. CURING SYSTEMS AND FORM DESIGN The curing system you use may affect how your forms are designed. We often reinforce the edges of forms to accommodate tarp rollers or other machinery to ride on the edges or sides of a form. Another common design detail is adding holes for steam, electric or other heat lines. When ordering new forms. Let us know if we need to make accommodations for any special curing methods that you use at your plant. These modifications are easy to incorporate when the form is being designed, but often difficult to add later. Products Insulated Curing Covers Closed cell foam insulation for superior performance I nsulated curing blankets capture the heat of hydration and retain moisture to help concrete cure faster. Hamilton Form s premium insulated curing blankets are made with closed cell foam insulation. Closed cell foam makes a big difference in the performance of an insulated curing cover. There are two types of foam-in-place insulation; closed-cell and open-cell. With closed-cell foam high-density cells are filled with a gas that helps the foam expand to fill the spaces around it. Open-cell foam cells are not as dense and are filled with air, which gives the insulation a spongy texture. Closed cell foam provides almost twice the insulating value of open cell foam insulation. Closed cell foam will not bunch or leave gaps like open cell foam, making closed cell foam a superior material. Hamilton Form blankets can be fully insulated or made with vinyl side skirts to fit over the side of the form. The insulated foam is encapsulated between outer layers of abrasive resistant 18-ounce vinyl and are custom made to fit your bed. The vinyl and foam layers are adhesive bonded and seams are heat welded. This eliminates sewing and prevents the seams from unraveling and leaking. Hamilton Form uses riveted D-rings on the ends because they are up to four times stronger than grommets. If you need a durable, high-quality, custom size curing blanket, call on Hamilton Form. sales@hamiltonform.com or call

5 Form Maintenance The Golden Rule? Keep It Clean F orms are a big investment, and nothing makes us prouder than seeing forms built by Hamilton Form that have been in service for many, many years. Steel forms can easily last for 20 years or more. In fact, we ve seen forms that were installed in the 1970s and are still in service today. On the other hand, we ve taken calls from customers who have forms that need to be refurbished, repaired, or even scrapped in as little as 5 years. The biggest difference in these two scenarios is in the way the forms are maintained. Concrete and debris build-up under forms can corrode the exterior of the form. mill scale. When absolutely necessary, you can lightly sand the casting surfaces with 60-grit or finer sand paper. It s also OK to use steel wool, a wire brush or a buffer fitted with a bristle brush. The secret to long-lasting forms (after starting with good, well-built forms), is form care and maintenance. The golden rule of form care is keep it clean. If you clean your forms after every pour and keep the area around your forms clean, many potential problems can be avoided. Cleaning concrete, caulk, dirt and other debris off your form s casting surface after each pour helps keeps the surface in good shape and ready to absorb a good coat of release agent or form oil, which you apply before each casting. Starting with a clean, coated form is not only good for the form, it also helps product strip easier. To clean your forms, use a putty knife or scraper to loosen debris stuck to the surface, then sweep or brush the surface clean. You can also use compressed air to remove debris from the form. The best options for cleaning hard to reach double tee stems and piling forms is to use the Cleaner Machine from Hamilton Form, designed especially for that purpose. When cleaning the casting surface, never remove the mill scale. Mill scale is the protective coating that helps protect the steel surface. Sanding or using harsh abrasives can easily remove Once you use one of these methods, you will need to re-season the metal to help close the porous surface that you ve exposed. This is done by applying a good coat of form oil or release agent and letting it soak into the skin. Be diligent about coating the surface for the first several pours or until a good layer of protection forms on the casting surface. Another area not to neglect is underneath the form. We ve seen plenty of forms rusted out from the underside because of debris and concrete build up under and around the exterior of forms. This allows moisture build-up and that leads to rust. Once rust starts, it progresses rapidly, making this an area to be diligent about. Debris around the exterior of the form can also damage connections. If you have a self-stressing form, build-up around the exterior of the form can prevent form movement during stressing, damaging connections and the form. Finally, debris build-up is a safety hazard. The bottom line? Keep your form s casting surface clean, check and clean debris from the underside of your forms often, and you ll be rewarded with many years of reliable service from your steel forms. Hamilton Form Tarp Roller Insulated curing blankets can be rolled out and re-rolled using a Hamilton Form Tarp Cart/Blanket Roller. The cart can roll on the edge of some forms, on tracks next to the bed or we can build a wheeled, steerable cart. Each roller machine is custom made providing you with the features and flexibility to improve your production process.

6 Hamilton Form Company, Ltd 7009 Midway Road Fort Worth, Texas Ph Fx Saturday, April 18, 2015 National Shooting Complex 5931 Roft Rd., San Antonio TX, F or the past several years, PCMA of Texas has been holding an annual event to raise funds for Pompe Disease Research. Pompe Disease is a rare genetic disorder. Raising awareness and funds for a rare disease is difficult at best, but thanks to the dedication of PCMA of Texas and the support of the precast community, since 2011, PCMA of Texas has raised over $500,000 for Pompe Disease Research! Join PCMA of Texas in their mission. The event takes place Saturday, April 18, 2015 in San Antonio Texas at the National Shooting Complex. Sponsor a group, be a shooter, attend, contribute to the silent auction, or simply make a donation. The event is designed for all ages and all skill levels and is always fun. More information can be found at for Pompeii Or contact Jorge Hinojosa at Bexar Concrete: jorge.hinojosa@bexarconcrete.com or (210)