Fluoride Action Network

Fluorogypsum: Old base materials causing cracks in resurfaced roads

Source: The Advocate | January 9th, 2014 | By David J. Mitchell
Industry type: Phosphate Industry

GONZALES — Only months after being widened and resurfaced earlier this year, a new 350-foot section of Roddy Road in Ascension Parish began cracking and heaving.

Looking like what happens to corn bread freshly baked in the oven, the cracks marred what was otherwise a welcome $1.85 million investment to a one-mile stretch of a key north-south connector for Ascension.

The culprit for the broken road wasn’t poor workmanship, parish officials and engineers say, but the legacy of road work 25 to 35 years earlier.

Under the old parish Police Jury, parish officials used two kinds of locally produced industrial by-products as road base: fluorogypsum, marketed at one time as Florolite, and Pisolite. Sometimes colloquially known as “red mud,” Pisolite is a chemically related but texturally different material.

Jason Taylor, parish chief engineer, said fluorogypsum and Pisolite undergo an unwanted reaction when mixed with the cement used to stiffen old road bases during repair jobs. This reaction unintentionally increases the volume of the base material and, in a few months, can crack the new asphalt on top.

“That’s the great and horrible thing about this at the same time. If it’s gonna happen, it’s gonna happen quickly,” Taylor said.

Glenn Shaheen, who owns a firm that has done engineering work for parish government since the early 1990s, said the materials are “probably fairly widespread,” though the locations are not entirely known.

Shaheen said the materials were seen by police jurors as a cheaper alternative.

“When you think about it, these guys, these leaders are trying to make an improvement and here we’ve got a local product here that’s very inexpensive and we can put on our roads,” Shaheen said.

The cement problem has meant the parish regularly tests for the base materials on road repair projects and each year replaces a few roads with the old base.

Taylor estimated the parish has reconstructed 6.5 miles of parish roads in the past six years with fluorogypsum or Pisolite.

Engineers tested Roddy for fluorogypsum and Pisolite every 1,000 feet, found some and removed it. But Taylor said the section in question was missed by testing and had Pisolite, which does not look any different from more traditional road base materials.

Fluorogypsum is a by-product of hydrofluoric acid produced by Honeywell in Geismar along La. 30.

Pisolite and red mud are by-products from the refinement of bauxite ore into alumina, a material that is turned into aluminum. Pisolite, which was sold by the old Kaiser Aluminum plant in Gramercy in the late 1980s, is stored in large dry stacks surrounded by levees.

Although Ascension is trying to get rid of its fluorogypsum and Pisolite roads and East Baton Rouge Parish refuses to use either product, the state Department of Transportation and Development lists fluorogypsum as an economical alternative to stone road base.

Mark Morvant, director of the Louisiana Transportation Research Center, said fluorogypsum has been in and out of state road specifications for years because of construction issues. Fluorogypsum temporarily turns soft when wet, but if properly sealed, the base remains solid. Morvant said fluorogypsum in state highways has held up well after a few decades of use.

“If it’s built properly once it is sealed, we’re not finding any real long-term issues with our roads,” Morvant said.

He said DOTD has experimented with different additives in lieu of cement to harden fluorogypsum and make it less sensitive to water.

Last year, the agency mixed slag, a waste product of blast furnaces, with existing fluorogypsum under the shoulders of Airline Highway in Ascension Parish south of La. 22 and has had success.

In addition to raising concerns with cement, both materials contain naturally occurring trace amounts heavy metals, such as arsenic, and radioactive particles, such as Radium 226, the U.S. Environmental Protection Agency says.

Wilma Subra, technical advisor for the Louisiana Environmental Action Network, a nonprofit advocacy group, said such contaminants, especially as a road base, could present a leaching risk to surface water and groundwater, but industry officials say repeated testing has shown both materials are safe.

“All materials provided have been well below regulatory limits or showed no detectable quantities of these substances,” said Peter Dalpe, spokesman for Honeywell, which sells fluorogypsum as road base.

Department of Environmental Quality officials authorized reuse of fluorogypsum as a road material in 1987, saying then that it posed “no radiological hazard from use in this manner.”

Sam Phillips, DEQ assistant secretary, said he has no knowledge of DEQ ever authorizing Pisolite or red mud as road base. But an EPA report from the early 1990s says the former Kaiser Aluminum plant — now Noranda Alumina — produced 72,920 metric tons of Pisolite in 1988 and sold some of it for construction of farm roads.

John Parker, Noranda’s spokesman, said Noranda has not sold Pisolite for roads since the company took partial ownership of the plant in 2004.

But Noranda is asking DEQ for permission to use red mud as fill material for levees and for road embankments, DEQ documents show. Noranda conducted numerous leaching and radioactive exposure studies for red mud, which it calls recycled processed bauxite, and says it does not pose a radiation or leaching risk.

Back in Ascension, the parish closed the problem section of Roddy earlier this month and spent an additional $118,000 to remove 18 inches of the old Pisolite base, replace it and repave the section of highway. The work was largely finished Dec. 19.

“I hope they did a good job,” said Richard Varnadore, 51, who lives with his wife, Donna, and other family members just north of the bad spot.