Less than two decades ago, most large warehouse concrete floors were constructed using a strip-pour methodology with truss-type vibratory screeds. This methodology yielded fairly consistent results, a predictable sequence of construction, and very predictable and manageable pour sizes.
A typical day's pour was 10,000 square feet. Flatness and levelness were judged mostly on the basis of "how the slab looked" or the old 10' straightedge was hauled out to see if the floor met 1/8" in 10' flatness specifications.
Today's warehouse concrete floors are often placed at a 50,000 square foot per pour pace, with flatness and levelness being judged on a more scientific and routine basis using sophisticated measuring tools like the "dip-stick" or "f-meter." The result is that today's floors are built four times faster and are more than twice as flat and level as they were build decades in the past.
Question: What happened?
Answer: Tools, Technology and Capitalism.
Like most industries, constructing concrete floors is competitive and demanding. Owners want their floors done faster, flatter, and cheaper than ever before. The drive to achieve these goals fostered an eagerness among concrete contractors to push the performance envelope. Contractors have always achieved the performance push with innovative machinery. Certainly, there are many tech-tools that have arrived on scene in the past decade to make this possible: ride-on trowels, early entry saws, and Laser Screeds are just a few. It was a certainly a confluence of many new tools, admixtures, placement techniques and other industry changes that led to today's extreme productivity and quality levels. The Laser Screed may, however, stand as the most dynamic and influential of them all.
The Laser Screed was developed in 1985 by Paul and Dave Somero, owners of S&S Concrete Floors, Inc. S&S is a New England-based concrete contractor that specializes in concrete floor construction. The first Laser Screed flowed from their desire to build better floors faster.
The prototype machine was built only for S&S's use, with no real thought to create a new product or company. The basic concept was to use lasers and hydraulics to control grade, rather than forms, semi-rigid vibratory truss-screeds, and raw grunt effort. In the strip-pour mode, the forms control the grade level at the ends, and the accuracy and rigidity of the vibrating truss controls the grade in the middle. A heavier truss is more rigid and, as a consequence, requires stronger forms to hold it up. Widening a pour beyond 25 feet required stoutly braced and carefully set end forms, good materials and skillful form-setters.
Controlling the floor grade using "lasers over hydraulics" meant that sturdy perimeter forms were less important. The function of the perimeter forms was reduced to horizontal containment, with much less of a grade-carrying role. This meant that floors could be constructed faster, with cheaper materials and less supervision. Fundamentally, getting rid of perimeter grade carrying forms liberated the contractor from pouring narrow strips. With a laser beam as the grade-carrying device, much wider pours could be attempted.
The first Laser Screed was a four-wheel drive, diesel-powered machine with a fixed 20' boom and a 12' wide screedhead. The machine was maneuvered into position and set on stabilizers. While the screedhead was mechanically powered out to the end of the boom, it would be lowered hydraulically into the laser zone. At this point the lasers would take over and communicate "go-up" or "go-down" commands to the hydraulic valves as the screedhead was powered back in towards the machine. The result was an accurately screeded 20' by 12' area. The machine was then repositioned to make subsequent passes, overlapping about one foot on the left and advancing the 12'x 20' sections from left to right.
Somero's Copperhead Laser Screed
Compared to today's advanced Laser Screed, this first machine was quite primitive. Yet the concept worked well enough to encourage significant investment and engineering to develop a better unit. Machine # 2 had a telescopic rotating boom as well as the current three part, plow auger vibrator arrangement that today's Laser Screeds have.
S&S saw such dramatic results in their own productivity and quality that they decided to market the idea, which gave birth to Somero Enterprises, manufacturer of today's Laser Screeds and numerous other highly innovative tools for screeding concrete.
The Somero family worked diligently over the ensuing decade to convince the industry to adopt its new, patented "wide-placement" laser-controlled pouring techniques. At that time the Someros believed that there was a potential market for perhaps 50 to 100 units, each selling for about $150,000. Dozens of World of Concrete exhibits, hundreds of "in-the-mud" demos, thousands of sales calls, and a wave of success on the part of the early adopter-contractors helped propel the company to its current leadership role in the concrete screeding industry.
Today's Laser Screed is an extremely sophisticated engineering marvel. It has very modern joystick controls, proportional hydraulics, advanced laser control systems, innovative operator ergonomics, and much-improved screeding and consolidating mechanisms. Contractors who use Laser Screeds have raised the standards for daily productivity by over 400%, and they have dramatically improved quality by routinely delivering floor flatness and levelness readings that exceed pre-Laser Screed tolerances by over 200%. Large daily pours of 50,000 square feet have now become routine, and FF/FL numbers scoring above 50 (Superflat category) are also very common among large, experienced Laser Screed contractors.
Somero's latest entry, the new SXP
It will be exciting to see what the contracting community achieves over the next decade or so with walk-behind Laser Screeds. My guess is that your everyday concrete floors are going to get done faster and flatter, with significantly lower cost. The "bottom line" usually gets the final vote, and lately it has been a vote in favor of Somero.
|Tom Oury comes from a concrete family. His father is a retired cement mason in Chicago. His grandfather was a concrete contractor. Both brothers work in the industry, as Tom always has. Tom presently serves as Western Region Sales Director for Somero Enterprises. He resides in suburban Chicago with his wife Pam, and children Emily, Jillian and Samuel.|
© 2005 L&M Construction Chemicals, Inc. | ConcreteNews Winter 2005.