Tilt-up construction is easy, right? Concrete is poured into a wooden formwork lying on the ground and left to cure. Then a few days later (when it has finished baking), it is tilted up into the air by a crane and walked to its final destination. The concept is so timeworn that even Thomas Edison experimented with the idea back in the early 1900s, though construction looked a bit different back then: a wood mold was made for the tilt-up panel, jacked into place once the concrete finished curing, and then reused for the next panel. The methods were different, but the end result was the same: fast, efficient, and economically built structures. Where can it go from here?
Modern application of tilt-up construction is often associated with warehouse facilities. Warehouses require solid, strong + economical walls to span long clear heights and handle unexpected impact loads from lifts, fork trucks, etc., while still meeting a tight schedule and cost-efficient budget. As a result, concrete walls have always been a go-to for warehouse construction. Now, with tilt-up panels that can stretch over 50 ft tall and can be cast + cured in a fraction of the time needed to fabricate cast-in-place concrete walls, tilt-up construction seems like the perfect solution for timeworn schedule + budget discussions. Plus, warehouses always resemble giant boxes. If they can be put together quickly and efficiently, who cares if they are a bit squarish?
But what if there were other options?
Not commonly known, tilt-up wall panels do not just come in solid rectangle concrete shapes. Cast-in reveals such as thin brick and textured stones can convince viewers that these walls are masonry structures. Concrete stains and additives might make you think the walls are made of sand or wood. Curved and asymmetrical panels may have you convinced these walls are not made of concrete at all.
When firms like Schaefer have diverse portfolios, they can take an age-old technique like tilt-up construction and apply it to a whole new market that’s ready for a change. Or, tweak that age-old technique and make it something better, faster, cheaper and more eco-friendly.
Let’s take a look at where tilt-up walls are trending these days.
Tilt-Up Construction Trends
Warehouses, Offices, Schools, Healthcare, Churches, Houses, Parks
How tall are warehouses these days? A century ago, the average warehouse was around 20 ft tall. Nowadays, warehouses need to provide 40+ ft of clear height inside the building – which means roofs are nearly 50 ft above the ground, with walls that are 55 ft tall, and footprints that are over a million sq ft. Do you know how many football fields can fit in a million sq ft? (Answer: about 17.)
As warehouses continue to grow in size, new demands are being placed on the wall designs. Walls need to be taller, stronger + multi-story. They need to be built fast and within a tight budget. This is where tilt-up panels shine. Tilt-up construction allows walls to be fabricated + erected in a matter of days, whereas steel + masonry can require months. Recycled materials are often utilized within the concrete, and new + intuitive ways of thinking are helping incredibly tall panels become leaner + stronger.
Other markets are now noticing the potential applications of tilt-up wall panels. Knowing that wall panels can span multi-stories and look like brick buildings (or sand or wood or granite or pretty much anything other than concrete), designers have started exploring the use of tilt-up panels for new offices, schools, healthcare, and churches. Tilt-up panels are constructed fast, they’re sturdy, they can be amorphic, and they can provide outstanding insulation + energy efficiency. School renovations with August deadlines, warehouses with November deadlines, churches + medical office buildings (MOBs) with one-month-ago deadlines are starting to appreciate this evolving construction method. Tornado structures are leaning more and more often toward tilt-up concrete designs to provide ample protection for community members. Even houses are being fabricated out of this beastly construction material!
Besides infiltrating most markets, there is also a fair amount of innovation happening with this type of construction.
Tilt-Up Concrete Composite + Non-Composite Panels
Composite + non-composite panels have been around for over a decade; however, they have been brought back to light in recent years as new energy code requirements have been implemented. Both these panels include a layer of insulation sandwiched between two layers of concrete, like precast, but directly built-into the tilt-up panel while it’s formed in the field. Composite panels have equal reinforced concrete layers tied together using connectors (i.e. 3 inches concrete + 2 inches insulation + 3 inches concrete), whereas non-composite panels have a thicker interior reinforced concrete layer comparable to a standard panel and a thinner exterior architectural layer (i.e. 7 ¼ inches concrete + 2 inches insulation + 3 inches concrete veneer).
While both composite + non-composite panels are more aesthetically pleasing than standard tilt-up concrete panels as the insulation is hidden from view, composite panels use the insulation gap as an opportunity to increase the structural performance of the panel. They use less concrete and less steel reinforcing than its standard counterpart. They weigh less, which helps reduce the footing size + seismic forces as a more efficient design. With that said, the additional cost of connectors, their longevity and the complications involved in lifting thinner layers of concrete must also be factored in.
Tilt-Up Concrete Form Liners
We already mentioned aesthetics. There’s a great chance tilt-up concrete wouldn’t have expanded from warehouses unless it could look the part on higher visibility buildings. Form liners can give the appearance of brick, glass, porcelain, sand, stone, tile, or adobe, and can add patterns from herringbone to basketweave, which has recently inspired designers to use tilt-up panels in the development of some more unique buildings. A tilt-up “brick” wall can be constructed in a fraction of the time and comes with its own natural insulation. In communities where buildings complement each other, form liners may be used to fit a tilt-up building into the neighborhood on a more cost-efficient budget.
Tilt-Up Concrete Fibers
We saved the most controversial for last. Tilt-up concrete can stand strong with the support of steel rebar embedded within it. Rebar is regularly used as a strengthening agent in all kinds of concrete applications; it holds the wall or floor strong even as the concrete begins to crack or weaken (and minimizes either from occurring).
The problem – steel is expensive and getting more so by the day. This pain point is ripe for a new solution. Enter: fibers.
Let’s start by saying that using fibers in place of flexural rebar in structural walls is not yet approved by the American Concrete Institute due to lack of testing. Until that happens, fibers can be used where flexural reinforcing isn’t needed, but crack control reinforcing still is (think slab on grade).
Fibers can be made of steel, plastic or glass and can be added into the concrete mix before it leaves the plant or onsite right before a panel pour. Glass tends to be the most popular right now, but even if steel is used, the amount needed to make these fibers, in comparison to temperature + shrinkage rebar, still drastically reduces cost. The use of fibers in wall panels was initially intended for blast construction by the Army Corps of Engineers. Its homogeneity made it a good solution to keep concrete secured like the laminated safety glass in a shattered windshield. And did we mention they’re recycled materials?
In eliminating the crack control rebar, it:
- Reduces the total tonnage of rebar
- Reduces the time involved in laying out + tying rebar
- Reduces the number of chairs (and any inaccuracies due to chair placements)
To sum it up, it saves on materials, labor + time (aka cost).
Something that started as a very primitive solution has and continues to innovate so that its very real benefits in time, cost + energy efficiency can be realized in most markets without losing aesthetics. We have a team dedicated to designing with tilt-up concrete and monitoring trends that could make it even more appealing to our clients. I myself am the 2019-2020 technical committee chair for the Tilt-Up Concrete Association. As the modern world and innovations adapt to our client’s need, so will we.