The silos on Bonded Material’s new plant.
Bonded Materials Company of Kapolei, Hawaii, needed a new facility for producing packaged concrete products. As the sole supplier of packaged concrete in the entire state of Hawaii, the company could not afford to have its existing plant out of commission while a new plant was being erected in its place. That meant the old plant would stay and a new plant would need to fit into a tiny footprint: just 35 by 105 ft. (11 by 32 m).
Being located in Hawaii posed another obvious problem for Bonded Materials: there are no manufacturers of plants for dry premix bagged product on the islands. The manufacturer it chose — Astec Inc. — is located more than 4,400 mi. (7,081 km) away, as the crow flies.
The plant would need to be designed to be no taller than 65 ft. (20 m) when erected so that it could be loaded horizontally on oversized trailers for transport from the Astec factory in Chattanooga, Tenn. to San Diego, Calif. There, the plant would be put on a ship to be transported across the Pacific Ocean to Hawaii.
When the new plant had completed its journey, it would need to be put into place in that restrictive footprint — and then it needed to work exactly right.
“We’re far away from everyone,” said John Mitchell, director of operations of Bonded Materials. “The problem that we have over here in Hawaii is that if something doesn’t work right, we are pretty dependent on other people back on the mainland. We don’t have the technological expertise readily available here. Most of the equipment we buy is the only one of its kind on the islands.”
Given all of those variables that seemed to be weighing against a smooth transition to a new production facility, one might expect a nightmare tale. But, guess what? It worked.
An Aging Plant
Bonded Materials is a locally owned, independent company that got its start in 1955 and has been growing ever since. Today, its Hawaii facility is a Quikrete licensee. The company also has expanded its production facilities to Arizona and Texas.
In Kapolei on the island of Oahu, Bonded Materials makes a number of different dry, premixed products. The location’s original plant, built in 1980, could make a variety of products, but it was beginning to show its age.
“Our original plant was built like a Swiss army knife,” Mitchell said. “It is very versatile and can do a little bit of everything.”
Over the next few decades, the introduction of mega-sized home-improvement centers like Lowe’s and Home Depot created an entirely new kind of market for the company’s bagged concrete products. Suddenly, a plant that could do a lot of little jobs well just could not keep up with the demand for this one bigger job.
“A Swiss army knife is great when you’re on a camping trip, but it’s not so great for a big, specific job like rebuilding your car’s engine,” said Mitchell. “That’s where we were: we realized that one-size-fits-all didn’t work for us anymore. So we decided to go with very specific plants for very specific operations.
“As it turned out, that was the best decision we ever made.”
The Puzzle of Modernizing
Mitchell had seen a presentation made by an Astec Inc. representative and the quality of the company’s dryer impressed him.
“I contacted Astec and explained our situation,” said Mitchell.
“Initially we thought maybe we could just renovate the existing plant by putting in a new dryer.”
Then, they looked closer at the nearly 30-year-old plant and realized that it was time for a more major change.
“It’s kind of like giving an 80-year-old man a heart transplant,” said Mitchell. “There is only so much you can do with a plant that was built in 1980. So that is when we decided to switch gears and go in a new direction. As it turned out, we decided we would have two smaller plants instead of one big plant.”
After working extensively with Astec engineers to design the dry premix bagged product plant to Bonded Material’s exact needs, the facility was fabricated and erected at Astec’s manufacturing facility in Chattanooga.
“As they were working on building the plant, we took their drawings and had our engineers in Hawaii design the footings in compliance with all of the building codes,” said Mitchell. “When the plant was erected at Astec, I went and looked at it on their pad there in Tennessee. Then they disassembled it for shipment to us, here in Hawaii.”
The modular plant was placed on 14 oversized trailers and hauled cross-country to California before being shipped across the Pacific Ocean.
Once in Hawaii, the engineers and technicians at Bonded Materials, along with Astec technicians and some local contract erectors, worked together to see that the plant was erected correctly. Then, under the supervision of Astec technicians, the plant started up in the spring of 2010.
Throughout all of this, Bonded Materials did not lose any production days.
“The original plant ran through the duration of the construction,” said Mitchell.
That 1980 plant’s days are numbered, though. Mitchell explained that the long-term use for the new Astec plant is to run only sand-related products that use cement, sand and additives. The old plant will eventually be replaced by another Astec plant.
“Right now, our old 1980 plant is still running, but it has a limited number of years left on it — maybe a year or two,” said Mitchell. “So we are working with Astec to replicate the things that we love about this new plant and use the features to customize another new one. Eventually, we will have two smaller plants that can run jointly or independently. Since we are the sole manufacturer of packaged concrete here in the state of Hawaii, we need that sort of redundancy.”
Small and Efficient
“Right now, we cruise at about 50 tph,” said Mitchell about the new Astec dry premix bagged product plant. “That is perfect for our operation. This plant was designed for a small footprint in a small market. We run this plant for very specific reasons for very specific needs, and we are more interested in achieving accuracy and minimal manpower.”
Mitchell explained that it only takes two people to run the entire plant.
“For us,” he said, “that is a thing of beauty.”
The new Astec dry premix bagged product plant is a custom-built combination of a continuous dryer system coupled with a batch mixing system. It features a parallel-flow dryer drum that measures 5.5 by 30 ft. (1.7 by 9 m), and a 32 MM BTU/hr natural-gas burner. Other key components include the following:
• A single-bin, relocatable wet-material feed system with an 8.5 by 14.7 ft. (2.6 by 4.5 m) top opening and a 4 by 4-in. (10 by 10 cm) bar grizzly.
• A 2 by 32 ft. (0.6 by 9.8 m) collecting conveyor carries material to the dryer.
• The dried-product conveying system features two 64.8-ft. (19.8 m) bucket elevators for feeding dried aggregate to the aggregate silos.
• Two aggregate storage silos each have a 533-barrel capacity.
• The material-mixer system includes a pan-type mixer mounted under the aggregate silos. Below two load-out doors on the mixer are a surge hopper with a discharge auger for mixed product discharge; and another surge hoper with two augers that feeds material to the bulk bag bag-loading system.
• Two cementitious-material storage silos each have a 600-barrel capacity.
• A mass-flow weighing system with a weigh pot is used for powders.
All of these components are managed by the Astec TCII-DB (Total Control II-Dry Blend) control system. The systems’ PC-based interface is located in a 9.75 by 9.75-ft. (2.9 by 2.9 m) observer-style control house.
“There are no mechanical interfaces,” said Mitchell. “Everything is run by a PC. While looking at a computer screen, I can turn anything on or off. It’s all self-monitoring. Every rotating part has a sensor on it, so it tells me the moment we have a problem. I can look at the screen and see every motor and gauge and how much amperage it is drawing. If something is out of line, I know it before there’s a big problem.”
In addition to the ease of monitoring the operations of the plant, the entire back-end of the production line is automated.
“Astec built the front end of our plant: they dry our sand and they store it, and they designed our batching plant with the mixer,” explained Mitchell. “That system takes the finished product and discharges it to a fully robotic line that was built by another company, one that specializes in robot integration.”
Robots fill the bags, seal them, weigh them, and stack the bags on pallets for shipping.
“The only thing a human has to do is watch the computer screen and load the hopper at the front end of the plant with sand. And then someone just watches the robots pack the bags. There is no manual labor involved,” said Mitchell. “The high level of automation makes this plant truly unique.”
Level of Commitment
In spite of the complexity and tight specifications that came with this project, Mitchell said the entire process ran smoothly. And that was a pleasant surprise.
“We were a little insecure at first because we have purchased things in the past that were said to work a certain way — and they didn’t,” said Mitchell. “But I was really impressed with Astec’s commitment to sending people over here to get the plant up and running. They did whatever it took — whatever it took — to get the plant to work the way they said it would. They never rushed us, or imposed a deadline. Their commitment to getting the plant up and running was impressive. They exceeded our expectations.”
When asked if he had any advice for those looking to specify and install a new production facility, Mitchell cautioned producers to take their time and do a lot of in depth research.
“It’s not like going to buy a used car, where you just go and kick the tires,” he said. “You really need to take the time to know exactly what you want. Because Astec can make anything you want — if you know what to ask for.
“Take the time to do your own planning and put together a list of all the features you want and the things that are important to you,” continued Mitchell. “Do the research, visit some other plants, talk to people in the industry — because there are a lot of really neat things you can do.”
He also suggested setting a realistic timeline that accounts for the extended process of researching, designing, permitting, and installing the new plant.
“In our case, the plant was finished and erected at Astec’s yard in Chattanooga, but back here in Hawaii we ran into difficulties with putting in new utilities — the electrical and gas lines — to accommodate the plant. It took me a year longer than I had planned, but that was not Astec’s fault. In fact, that really pleased me, because they were very patient. I stalled them at the very end and picked up the plant as late as we could, but they never pushed me.
“I am definitely, really happy about that kind of commitment,” said Mitchell. “Their techs will do whatever it takes to make sure the plant does what it is supposed to do.”