Concrete Plans

Today the 90-acre facility has two crushing operations—one each for concrete and asphalt—and a wood recycling plant.

The latter is a Morbark 1300 tub grinder with an attached grapple to feed it the pallets, obsolete fencing and tree branches accepted by Oxford. No painted or stained wood is processed, and the main product is mulch. That plant’s main enemy is metal, says John Kent, who is now the company’s president. The tub grinder does a great job with the wood it processes, he says, but not with the metal that accidentally get in there once in a while.

The same situation applies at the asphalt recycling plant, which is run by two people. No magnets are part of the single-stage crushing operation. A Komatsu WA500 loader with a 7-cubic-yard bucket feeds the Telsmith 5263 horizontal shaft impactor that does the crushing. Screening is done by a Proscreen 6 x 16 foot double-deck, but only one of the decks is used to make the recycled asphalt product that is used in a couple of markets.

One, says Kent, is the traditional hot-mix market, although today most of the local plants are using millings from current road projects instead. Millings are far more prevalent today because the local roads have been built up with 2-inch overlays over the years, and now they have to be milled down or they will be too high for trucks to go under bridges and the like.

Oxford’s biggest market for asphalt is municipalities looking to control dust on gravel roads.

For the two-stage concrete recycling plant managed by three people, some similarities exist with the asphalt recycling operation, in that a Komatsu WA500 loader feeds the plant and a Telsmith 5263 is one of the crushers. In between those two pieces of machinery is a Nordberg (now Metso Minerals of Waukesha, Wis.) C140 42- x 55-inch jaw crusher as the primary crusher and a Hewitt-Robins, 8- x 20-ft triple-deck screen. In addition, three magnets are on the line to remove rebar.

"We don’t really need that big of a jaw crusher," says Kent, "but we got it so we can accept larger pieces of concrete without so much preprocessing."

However, Oxford’s goal is to avoid as much preprocessing of concrete as possible. Not that it isn’t equipped to handle it. A Komatsu backhoe is fitted with a Stanley LaBounty (Two Harbors, Minn.) pulverizer to handle oversized pieces. This is the company’s second LaBounty pulverizer, having worn out the first. Kent prefers the pulverizers to the hammers, saying pulverizers have demonstrated impressive durability.

Oxford did experiment with a LaBounty shear attachment to cut up concrete with rebar, and to try to get the rebar down to a 3-foot length to get more money for it. "It worked," Kent says, except that it took longer than the pulverizer does, and at three times the cost. Now Oxford charges a larger tipping fee for heavily rebarred concrete, to a point where it can be cheaper for the generators of such material to take it to the local landfill.

There are three main products Oxford Recycling makes with the recycled concrete. The biggest seller is a 3/4-inch roadbase that can meet the state department of transportation (DOT) specification, but little is actually sold to the DOT. A 1-1/2-inch rock was originally developed for use at muddy construction sites. "But the new craze is to use it for backfill behind retaining walls. It will pass the moisture and you don’t want anything that will retain moisture to put a lot of pressure on your wall," says Kent.

The newest product is a 3-inch rock. Kent says, "Lots of municipalities are now using that as a tracking pad material for right before vehicles exit on a public roadway. The thinking is as the trucks drive across this and turn to go out, they will be scraping their tires and getting some of the dirt off the tires. We like crushing it, it comes out readily, and it’s cheaper to produce than going down to 3/4-inch."

Acceptance of recycled product in the Denver area has been pretty good for several years now, says Kent. "In the early 1980s, when we were trying to get ourselves established, acceptance was a major problem. We spent a tremendous amount of time and money running these tests constantly to show municipalities the material’s engineering characteristics. Some of those people were going to retire in a few years, didn’t want to try anything new. A lot of that has gone away, but still a few of them around. But it has been around for so long now, and so many are doing it, I think it has become mainstream."

Government and contractors are not Oxford’s only customers. Kent says the company excels at serving the general public in the Denver area as well. In addition to asphalt and gravel for driveways, the company markets a variety of sand, gravel and mulch products. Many of them aren’t made at the site, but are provided as a convenience to customers.

Another convenience to them is the fleet of trucks Oxford Recycling employs. These include both roll-off trucks to bring in material, usually concrete, as well as haul trucks to deliver to the homeowner or the small contractor who doesn’t have the truck to spare to get the material.

Indeed, it is transportation costs that set up the Denver-area concrete and asphalt recycling market, says Kent. "Transportation is as much as 50 percent of the cost of our business," he says. "At that big of a number, it doesn’t pay to truck the stuff across town."

Oxford Recycling is in the southwest quadrant of the city, and Kent says as it is the only site in that area, it doesn’t compete with the other recyclers in the city. "We don’t really compete with the competitors, and they don’t compete with us because they are not in our area."

Kent believes one of the biggest challenges facing the construction and demolition recycling industry are the NIMBYs who don’t want businesses such as his anywhere near them. "Businesses like ours start out on the outskirts of town because no one wants us around," he says. "Then [developments] fill in around us. We all want new and better roads, want these products and services, but they don’t want it around them. I understand their point, but there needs to be an equal balance here."

Oxford Recycling is surrounded on all four sides, with only one side being an industrial neighbor. On a higher level on its west side is a residential neighborhood that overlooks the plant. The close proximity of the homes means that dust control is very important at the site. A 2,000-gallon water truck patrols the operation full time. In addition, most of the main roads on the site are paved with recycled concrete or paved with hot mix or crushed recycled asphalt. "That saves on using the water truck as much," Kent says. "If you use the water truck a lot, you need to have a motor grader right behind it because of the ruts."

Even after more than 21 years in the concrete recycling business, Kent doesn’t think he is in a rut by working in the same concrete, asphalt and wood recycling industry all that time. "If you didn’t enjoy it here is no way you could do it that long," he says. "I plan on doing this a number of years more."