When forced to recreate their city, San Francisco engineers and planners modernize by adopting the newest construction technology. For example, the San Francisco-Oakland Bay Bridge complex exhibits concrete ingenuity with each revision.
But in the decade following the catastrophic 1906 earthquake, planners, engineers, and contractors adopted new technology to rebuild their community to a higher standard. Proud of their accomplishments in 1914, the community began preparing to host the 1915 Panama Pacific International Exhibition. It was an expansive event highlighting not only the achievements of rebuilding San Francisco, but also the Panama Canal’s opening. At the groundbreaking for the exhibition, President Grover Cleveland, impressed by the city’s achievements, nicknamed San Francisco “The City that Knows How.”
It was in this spirit of serving the city that knows how that Central Concrete Supply Co., a business unit of U.S. Concrete Inc., chose to upgrade its San Francisco-based ready-mixed concrete operation. The team at Central Concrete developed a plan to ensure its investment would be ready to meet the challenges of a city that knows how to do right for the future.
While the project’s initial focus was to replace aging batching equipment, the team took a broader approach, looking at the upgrade as a strategic move. The team began by looking at the local market’s future. They recognized a vastly changed construction environment from when the plant was last modernized. “We wanted to build a plant that serviced our customers, not only this year, but into the next decade,” says Jeff Davis, Central Concrete’s vice president and general manager.
Davis has witnessed more than three decades of concrete production advancements. He urged his team to adopt a new production process to meet concrete construction’s evolutionary path. Local engineers and contractors have been incorporating more performance mix designs into their projects. These often include a variety of custom graded-aggregates and blends of cementitious materials. Also, concrete contractors are adopting faster casting and placing procedures that require faster production rates without sacrificing mix uniformity or quality.
From an internal perspective, Davis cites several operational enhancements based on the team’s goals. To efficiently batch performance mixes, the plant required a versatile selection of hoppers, bins, and silos from which to draw ingredients. They also needed to use their land efficiently to allow quick and safe traffic flow. And they had to maintain an environmentally sound operation that supported its ongoing Green-Star Certification.
Davis says the preliminary discussion, planning, and execution was extensive but rewarding. His team partnered with Plant Outfitters, a San Antonio-based engineering firm. Davis believes the upgrade was a success for one important reason: “Both the engineers and our production staff believed the ultimate goal was to create a plant that would batch high-quality concrete for all customer situations,” says Davis.
Producers across North America are reinvesting and, in turn, reinventing their batching, mixing, and material handling operations. As the team at Central Concrete discovered, their future is now. Today’s plant capital investments may the first in a decade. And as every plant manager knows, it could be just as long before they get another chance. Fortunately, producers are in an industry with engineering and plant configuration experts who know how to do it right.
Why the sudden increase?
Concrete producers have always been cautious about investments. So what’s causing this renewed interest? Several plant design engineers say the most common reason is that plants are just wearing out. In many areas, producers are operating plants fabricated and erected in the 1960s and 1970s.
Trying to meet increased production targets with old equipment can minimize operating margins. Producers are discovering that spare parts are no longer available for old plant components, says Herbert Botzenhart, executive vice president of Liebherr Concrete Technology. And with production levels increasing, plant downtime must be minimized, if not eliminated. “What had been routine repairs are now becoming more costly and timely, especially when trying to secure custom-made parts, and in terms of downtime,” says Botzenhart.
Another factor driving many capital improvements is the increasing environmental regulations placed on all types of manufacturing. One plant design engineer said that a producer-customer sought immediate help when their plans to reopen a mothballed ready-mix concrete plant were stalled. In the five years of nominal plant activity, the local community seemed to have forgotten the operation existed. But the same neighbors complained when daily production began. Although the plant was operating within its permitted level of emissions, managers installed updates to dust suppression equipment and process water treatment procedures.
Developing a plan that results in a clean production plant is easier now than ever before, says Erik Johansen, vice president at Advanced Concrete Technologies Inc., a plant engineering firm. Johansen’s firm assists producers in both updating and constructing new plants. His firm has traditionally worked with precast concrete producers. Yet in the past, its staff is experiencing a pickup in design work from all concrete producer segments.
“Producers are looking for new batching and material flow technologies they can incorporate, ignoring the traditional labels of ready-mixed or precast,” says Johansen.
Aggregate and cement delivery procedures are a commonly shared technology for all production operations. When opening or updating a new plant, producers often start their planning with aggregate material delivery. For many plants, communities are becoming more concerned about increased daytime truck traffic.
Johansen recently designed a project that included below-grade truck unloading hoppers. The hopper accommodated both belly dumps and rear-end trailers to fill coarse and fine aggregate overhead storage bins. Johansen’s design resulted in a smaller footprint. The producer discovered an additional operating benefit. By eliminating double handling the material by a front loader during the day, they minimized ambient noise.
