As an architect, I am always interested in new finishes that can help add depth, texture and color to a structure. The wide variety of exterior finish products that are in today’s marketplace is almost unlimited. So too are the details and products used in their installation.
When on a jobsite, I cringe when I see multiple materials, tapes, fasteners and barriers used to create a reliable envelope that helps protect the building from the elements – especially where we live in the upper Midwest. Most failures occur where there is a joint in between materials that needs protection added to it to make the exterior barrier continuous. As we continue to expand the finish palette of our architectural precast concrete (see previous blogs on terracotta, graphic concrete, thin brick, 3D printing, form liners, etc) we want to make sure that they are as durable and reliable as one would expect to see with any precast finish.
With our new lightweight cladding systems (Slenderwall and Integrated Enclosure System – or IES) we are able to use precast concrete as a weather, air and vapor barrier. This helps us simplify and minimize the number of joints and fasteners needed to complete the building envelope. This also allows us to add other finishes to the face of the precast, knowing there is a very durable and reliable substrate protecting the building behind those finishes.
These finishes can include (but are not limited to) the wide array of metal and laminate panels. Designers will be able to expand the amount of materials that can be incorporated on these precast cladding panels, allowing for a much more unique design. Another benefit of this process will allow for these materials to be installed off-site in an enclosed facility, which will improve quality and speed up construction – but that will be covered in another blog . . . Stay tuned!
Tis the season to take a break and reflect back on Wells Concrete Blogs of 2018. Wells published close to 30 blogs during the past year discussing the attributes, advantages and future of precast concrete to help inform and educate our readers and followers. My blog will highlight what I thought was this year’s Top Four. I think it’s important to revisit what these blogs communicated, so here they are!
I’ve been in the concrete industry over 40 years and this misconception has always been a pet-peeve of mine. Gregg does a great job of simplifying the facts and Megan’s illustration is perfect!
“You see, cement is only an ingredient in concrete – it is a dried powder on its own. In this form, it would make a pretty worthless cement block or cement driveway; the powder would merely blow away in the wind.”
Bob’s blog was posted back in January 2018 and has probably fallen off everybody’s radar by December. Teams that work together are successful and teams that don’t work together are not teams. I would like to bring you back to the Six Steps he listed in becoming a better team player.
Accept that conflict is normal and can occur within groups. Conflict will be easier to deal with if each group member understands that disagreements play a normal and fundamental role in group formation.
Be willing to acknowledge good ideas even in the face of competition. Praising each other has a positive effect on the group by improving the probability of the project’s success.
Avoid backbiting and complaining about fellow team members. Should a problem develop do your best to solve it with that group member, addressing the issue directly and tactfully, or, if absolutely necessary, consult your supervisor.
Use your resources. Do not be afraid to ask questions and seek advice from those within your organization who can provide the information needed to increase the group’s knowledge and effectiveness.
Delegate according to your strengths. By first assessing the strengths and weaknesses of each group member, you are able to delegate tasks to the members with the strongest skills in that area. Giving assignments according to the interests and strong points of your teammates will increase your chances of success and efficiency.
Go the extra mile. Going the extra mile is not only one way to ensure the success of your project, but also an effective way to gain the respect of fellow co-workers.
Ryan explains the benefit of 3D printing to create complicated and complex modeling over materials (wood & plastic) of the past. University of Minnesota’s Pioneer Hall Addition & Renovation was a perfect project to incorporate this new and exciting technology for seamless forming for the window framing.
Concrete finishes have come a long way in a short period of time. For those producers who really care about their clients, it is important to step up and meet the challenge of providing the finishes those clients want and can use to beautify their structures. Today, finishes range from standard water wash and acid etching to polishing and creating “old stone” look-alikes. In addition, combinations of any or all of the above are achievable within the same project, even within the same panel. In fact, Wells has been showcasing our Mock-up Building to clients to demonstrate these abilities for the past two years, and is currently in the process of creating yet another Mock-up Building to showcase even more recent finish and feature innovations. Producers need to have strategies, a mentality focused on value and flexibility, and when the correct balance is achieved in satisfying your clients, you will be ahead of the game.
Communication is a critical piece to any successful business. As I mentioned in my last blog, communicating clearly with internal and external clients is so important for our days to run smoothly. Did you catch the key word there? The key word is: clearly.
Maybe you’re in a meeting with a team and you think everyone understands the answer as well as you do. This is where meeting minutes come in handy. I know it takes more time to go back and type them up and send them to the group, and quite frequently we’re going from meeting to meeting so we might not have that time. But, if nobody in the group took any notes, then there is no documentation about agreed upon action items.
Suppose you’re getting ready to pour a piece of precast concrete, let’s say a double tee for example. You met with the engineer and drafter and they talked about the piece, which is great, but nobody wrote anything down. It would be pretty difficult to know specific items about forming configurations, strand size, reinforcing spacing, amount of concrete, and connection detail locations. Now, back that double tee up with a detailed piece ticket showing all those items and it’s going to be much easier to get the piece produced correctly.
Give it a try. Make it a point to take notes during your next meeting and send it off to your group. See if it answers any additional questions or maybe helps clarify something within your group. It all goes back to communication and how clearly we interpret conversations.
Precast Innovators is not just a slogan, we live it every day. With eighteen engineers, both professional and EIT’s we can design, produce and build any precast/prestressed building. Seven of these engineers work full time on process improvement and product development; creating innovation in all departments.
Why dedicate so many resources to innovation? To make better product and better concrete buildings.
Double tee load testing
Double tee load testing
One aspect of being precast innovators is full scale testing. For us, full scale testing is the process of making a full size piece of concrete and evaluating the performance. Sometimes that includes breaking it. There are many reasons for full scale testing, including: validating design methods, developing new products, and developing new processes.
The first full scale testing I was involved with was load testing a parking double tee in 2005. A team of Wells Concrete engineers designed the test procedure and performed the loading. The reason for testing was to validate the double tee design for deflection and shear. The load test was successful – we loaded the tee with the equivalent weight of 30 cars in three parking spaces! I was surprised by the flexibility and durability of the double tee. After the weight was removed the double tee returned to be being flat.
Strand bond test
Strand bond test
Once a year I perform ‘A simple quality assurance test for strand bond,’ AKA ‘The Peterman Test.’ It is a PCI-approved testing method to verify that the concrete we pour bonds to the prestressing strand. Strand bonding is important because the potential energy in the prestressed strand transfers to the concrete through bonding. If there is a lack of bonding, the potential energy is lost. The test is simple. Load the beam to 100% of the theoretical capacity. If the beam does not break, we pass, and if the beam breaks, we fail. Since the creation of the Peterman Test in 2009, all the beams I have tested have passed.
Load testing dap steel on the end of a beam
Most of the time testing is well-planned and organized but sometimes it is necessary to skip the scientific process and simply ‘overload it and see what happens.’ One example of this was load testing dap steel in a beam in 2008. We know the design method of dap steel is conservative and we wanted to validate the capacity of the beam end. So we set three crane counter weights on the end of the beam, but we could not get the beam to break.
These are just a few examples of our dedication to quality and innovation. The Wells Concrete team will continue to create innovation where ‘breaking stuff’ is part of our job.
In the fast-tract construction world we live in today, designers, contractors and owners are looking more and more at precast concrete wall panels to shorten the time to completion. When they think of precast concrete wall panels their first thought is to flat wall panels because of the unlimited architectural shapes and finishes they can provide. At Wells we also offer double tee wall panels. Yes that’s right a double tee. Most people think double tees are only used for floor and ceiling construction in order to create long spans and open floor plans and in parking ramps. Double tee wall panels can be insulated or non-insulated for a quick, durable and economical / cost effective building system. An insulated double tee wall panel provides a thermally efficient structure and will have a panel make-up as follows: 18” stem + 2”exterior flange + 4” of insulation + 2” interior flange.
The exterior surface is a smooth steel form finish that can withstand decades of weather exposure and work related abuse. The interior surface is typically a smooth steel trowel surface that requires very little maintenance and low building operational cost. Both the exterior and interior surface can be painted as desired.
Double tee wall panels are ideal for high wall application and are thus used in warehouses, manufacturing facilities, industrial and agricultural applications, plus some large recreational facilities. They are versatile and moving a non-load bearing double tee wall panel to a new location can be an economical solution to a future building addition.
As Ryan Garden mentioned in a previous blog post – the 8th Edition of the PCI Design handbook removed double tee wall panels as a design example – but remember Wells still makes them. Maybe on your next project you might consider using double tee wall panels on the larger shop portion and dress up the office area with some architecturally pleasing wall panels.
Often the height of buildings using precast, whether for cladding or structural purposes, will be low enough where the height of a single wall panel or column can cover it. But what about when the height of a structure is beyond what a single wall panel or column is able to do, due to shipping, weight, or design limitations? Well when one panel can’t do it, we can just put another one on top of it. And another on top of that if needed. And so on.
This happens more than most might realize since the resulting horizontal joint is typically covered by the topping slab of the floor system in the case of columns and interior wall panel joints, and looks like an architectural reveal on the outside of the wall panel once it is caulked. To blend it in like this the split must occur below finished floor, but above the rough flooring system, whether it be precast or metal deck. This configuration is also advantageous structurally because the lower column or panel can be used to help stabilize the upper. Placing split joints mid-height between levels should be avoided, as this can create a hinge point in the system. When done correctly the structural aspect of the walls or columns will function as they typically do when it’s just a single member.
Depending on story heights, a stacked wall panel configuration may even be more efficient using the width of the panel to span each individual story height and the length of the panel to cover more wall length with each piece. This works well in situations where the exterior architectural finish can accommodate the horizontal joint at each level, such as thin brick, and results in less interior vertical joints. This can also help with constructability when the wall panels are load-bearing because it becomes more difficult to adequately support multi-level panels the higher you go.
If multi-level wall panels are needed, perimeter column and beam lines along the wall will likely need to be added to carry the loads and provide immediate support for erection of the wall panels. This greatly simplifies the installation, making it go much quicker. The cost savings associated with the decreased site time and avoiding the need for specialty equipment helps offset the cost of the beams and columns.
So even though it’s hard to put an exact number on the height of a wall panel or column, because they’re both incredibly dependent on each particular case, the take-away is this: it shouldn’t scare any one away from counting on precast to go the vertical distance.
If you have attended any sporting events or concerts in any of the larger venues, or even at the college level, you have most likely been seated on top of precast stadia. You might not have given it much thought, because you weren’t sitting right on the concrete, but on seating that was fastened onto the precast stadia sections.
As the architectural engineering and building trades have advanced, so have the structures that house these multipurpose facilities. Stadiums must possess a variety of attributes including an attractive look; family friendly interior, including ease of ingress and egress; design flexibility; and the ability to comfortably and safely house the attendees. The almost universal answer for modern sports venues has been precast concrete components.
Traditional precast concrete products for stadiums include stadia riser sections, raker beams, columns, a variety of structural wall panels, and hollowcore planking. These components can provide many options for architects and engineers.
Using precast stadia sections and other precast components, including stairs and intermediate steps, will provide many advantages:
A platform for all trades to work off of early in the schedule.
Precast stairs can be utilized at the same time to provide immediate access between floors
Longer spans to allow for more flexibility in the areas underneath.
Flexibility of design to allow varying rise and run.
Cost efficiency due to the rapid installation.
Excellent fire resistant properties.
Superior sound and vibration control characteristics.
Long term durability along with low maintenance.
Quality controlled production in a stable environment.
Year-round manufacturing and erection.
Early discussions with the precaster should be an integral part of the design process to maximize the benefits of the use of precast concrete in a modern stadium.
In the construction world there are a lot of unknowns that take place and if a General Contractor can find any avenue that they know will be reliable and make their life easier, that avenue would be using precast concrete components. Going with precast concrete components guarantees a smooth route for owners and designers in both the immediate and distant future. Three keys to making your project a success while using precast concrete components include maintaining schedule, safety of personnel onsite, and the quality of products and construction.
Maintaining schedule: Every project has a life cycle and every General Contractor wants to make sure that their milestones are met if not superpassed. Precast concrete is produced offsite and is cured in a controlled environment, then stored until the jobsite is ready for installation to take place. Installation can take place year round, so once the project’s jobsite is ready, the precast installer can begin installation at a much faster pace than other structural/architectural components that are built at the jobsite. As the old saying goes “time is money,” and every day that is saved on the back end of the general contractor’s schedule helps their bottom line.
Safety of personnel onsite: Making sure that your subcontractors and crews leave the jobsite the same way as they were when they arrived is important to us all. Luckily, the precast panel systems take some of the worker-safety liability away from general contractors due to our off-site production and small crews to install onsite; which means fewer trades and safety risks onsite.
Quality of products and construction: There are many variations of design and architectural finishes and mixes that can be achieved with precast concrete systems. From very smooth concrete, which is great for food processing, all the way to a glossy polish, which helps make your building pop aesthetically above all others. Installation crews do a fantastic job in making sure everything is installed to plan. They also help to coordinate with other trades onsite to ensure the construction life of the project continues moving forward to meet or surpass schedule expectations. Wells Concrete makes it a priority to ensure that the quality of our products meet or exceed the owners’ and designers’ expectations.
Today’s mid-rise and multi-use buildings can include retail space, office space and residential living units and parking.
The challenge with having multiple users is finding a single structural system that will accommodate the very different floor plate layouts for each without placing load bearing columns and walls in odd areas that will hinder the use of the space.
The parking area requires an open drive lane that is usually 24’ to 26’ wide to support two way traffic with 18’ to 20’ parking stalls on either side. The layout of the housing is driven by the location of the public corridor and gathering areas. Sandwiched between these two areas is often a retail or office space looking for as much open area as possible to customize their floor layout.
The solution is to use a long span precast truss system (ER-POST ™) that spans the width of the Building. The trusses are supported by precast concrete columns at the perimeter or outside of the structure. Hollow core precast plank bears on the top and bottom cords of the precast truss.
The precast trusses can span the width of the building up to 80 feet while the hollow-core can span from truss to truss up to 44 feet. Because the truss is both top and bottom cord bearing, they are only required at every other level leaving the levels between completely open. Lateral support can come from the precast stair and elevator walls.
This system gives users the freedom to layout their space without designing around interior columns while taking advantage of the benefits precast concrete. Fire rating values from 1.5 to 3 hours, low sound transition, durability, speed of construction and all weather construction.
Take it a step further and incorporate a one of our architectural insulated precast exterior wall systems to enclose the structure.
Precast concrete has the capability of incorporating other trades in a plant fabricated atmosphere. Components can be cast into the concrete, or it can be used as a platform to prefabricate other trades. This can take work off the jobsite, reducing congestion and shortening construction time. Additionally, plant fabrication can offer productivity and quality gains, and while some elements added to precast are tried and true, others are new.
Board insulation in sandwich wall panels has been around for many decades. A layer of concrete is cast, insulation is placed on top of that, and another layer of concrete is cast on top of the insulation (picture an oreo cookie). The two concrete layers are tied together with a pin (a.k.a. wythe tie) that passes through the insulation.
Some new items used in plant-installed insulation are non-conductive wythe ties and new insulation types. A variety of wythe ties that don’t cause a thermal break through the insulation are available from various manufacturers. These are becoming increasingly common as a greater focus is put on energy efficient buildings. Plant-applied sprayfoam insulation has been used by some precasters for more than a decade and is becoming more common. Currently, this means sprayfoam is applied to the interior of a precast panel. Sprayfoam and other high insulating materials may one day be used in sandwich type precast wall panels, offering greater R values or productivity.
Wells Concrete has experience with plant installation of electrical items and windows. The typical electrical item is vertical conduit and a box cast into the concrete of a wall panel. This hides the electrical elements in the wall. Wells Concrete has begun developing a stud-frame-backed precast wall that has potential for making plant installation of electrical elements even more efficient.
Plant-installed windows have been on the rise at Wells Concrete, as well as the precast industry as a whole, over the last few years. After a wall panel is cast, the windows are installed in the plant or storage yard using the same details and methods as field installed windows. The precast is then shipped to jobsite with the window installed.
In the precast industry, some precasters have developed flooring systems that incorporate plumbing, electrical, and other utilities. The utilities are plant-installed within a floor piece that may typically be 12ft x 30ft. The utilities are spliced together at the construction site after installing the precast. Other precasters have developed floor systems that serve as a modular platform. Various elements can be plant-installed on top of the floor piece. Many of the elements in a room have been installed in prototypes: stud wall, sheet rock, electrical wiring and fixtures, plumbing with toilet and sink, and cabinets. The assembly is shipped to the job site and craned into place.
Tim Edland, P.E.
Research and Development Director
Concrete buildings from hundreds of years ago are still in use today. Some say concrete can last up to 2,000 years, and there are certainly many structures around that are well on their way to such a ripe old age. Why? Because it gets stronger every day!
Unlike most other materials, precast concrete increases in strength over time. Concrete is designed to provide a reliable structure for many years to come, it is not uncommon for designers to design concrete building for a 75 to 100-year life cycle.
The Ancient Romans were the first to develop concrete as a building material. They accomplished this by mixing lime, water, and volcanic ash.
Concrete is used more than any other man-made material on the planet.
Six billion tons of concrete are produced every year.
The world’s largest concrete structure, Three Gorges Dam in China, consumed over 35 million cubic yards of concrete. Hoover dam consumed 5 million cubic yards.
Reinforced concrete is the only building material that is highly resistant to both water and fire.
Concrete is the best material for road construction. The first concrete road was built in 1909, and 30% of interstate highways are built with concrete.
The British Army used concrete to detect enemy aircrafts, and before radar, concrete was used to construct acoustic mirrors.
Concrete and cement are not the same thing. Concrete is a mixture of cement, sand, gravel and water.
Christ the Redeemer – Brazil
Reinforced concrete is the only building material used for underwater structures such as damns, piers, and sewer works.
Concrete has an incredibly high compressive strength: typical (psi) compressive strengths range from 3,000-7,000 psi.
The statue of Christ the Redeemer in Brazil was constructed using concrete and soapstone. The entire project took nine years and 635 tons of concrete to finish.
According to the Washington Post, China has used more cement during the years 2011-2013 than the United States has in the entire 20th century.