When Phil Foley moved from Maine to Buda, Texas, 1.5 years ago to work for Austin Materials and Industrial Asphalt and Aggregates as their VP of operations, he already knew a thing or two about spray paving. In fact, he’d even worked with a 1986 Midland spray paver, “one of the original spray pavers.”
Spray pavers combine the processes of the paver and distributor truck into one machine, spraying emulsion immediately ahead of laying and smoothing hot mix. Spray paving allows crews to perform the underseal and overlay in one action, eliminates the possibility of the public getting tack on their vehicles and offers a strong bond.
“I’ve noticed that spray paving has started to gain speed down here in Texas,” Foley said, “with some divisions spec’ing it in some jobs, or at least giving us the option to use it.” Now, he said, most highway jobs in the area are done with a spray paver.
According to Ryan Farrelly with Integral dx, makers of the Integral dx spray paving attachment system for Caterpillar pavers, spray paving occurs in all 50 states, “though it’s more popular in some states than others,” he adds. “Internationally, Mexico, Germany and Scandinavia are heavy into spray paving as well.”
Austin Materials did its first spray paving job in March of 2016. Before that, its sister companies would do any spray paving jobs for them. But, eventually, the application’s popularity in south central Texas made it necessary for Austin Materials to invest in its own solution.
“To be competitive, we needed to learn how to do it ourselves,” Foley said.
So, in December 2016, Austin Materials purchased its own spray paver. Or, rather, a Cat AP1055F paver with an Integral dx spray paving system attachment, both delivered in March of 2017.
Since then, it’s done five spray paving jobs, most recently completing a $5.7 million spray paving project for TXDOT totalling 60 lane miles: three lanes in each direction, plus both shoulders, for 6 miles.
“The scope of work on these jobs varied from performance mixes placed on some of the busiest highways to rural roads,” Foley said.
About Industrial Asphalt and Aggregates
Despite its recent growth into the spray paving market, Industrial Asphalt and Aggregates does so much more than spray paving.
The majority of Austin Materials’ work is state DOT work, but they also offer paving to the commercial market, private market and municipalities. Owned by Summit Materials out of Denver, Colorado, Austin Materials has six paving crews, one highway milling crew, one utility crew and one chip seal crew.
They also own four asphalt plants–three Astec double drums outfitted with the newest warm mix features and one ALmix plant–and two quarries. The plants are located in Florence, Mustang Ridge, Garden Ridge and Buda, Texas, and the quarries are located in Florence and Hays.
They produce between 850,000 and 925,000 tons per year, and lay about 80 percent of that with its own crews.
Industrial Asphalt and Aggregates was formed in late 2011, when two long-standing companies in the Austin area–Industrial Asphalt and RTI Materials–joined forces. Now, the company is one of Austin’s largest aggregate and asphalt producers, as well as the only aggregate producer in the Austin market.
What is Spray Paving?
Typically, Foley said, contractors will perform a chip seal / underseal and put the mix on top of that to create a barrier for moisture or a seal.
“But, south central Texas gives us the option to spray a membrane out of a spray paver and eliminate a whole other operation,” he adds. “Typically, what we do with the standard application is the chip seal is the moisture barrier and pave over it. But with spray paving, that is the actual membrane.”
The combined process allows Austin Materials to start paving 1.5 to 2 hours earlier than if you were to mill it out and then chip seal, and also eliminates driving over the tack.
Despite TXDOT’s success with and support of the spray paving process, some people still worry that the process doesn’t give the tack enough time to cure before laying the pavement. But, both Foley an Farrelly recommend learning more about the process.
“I suggest they do more investigation on how emulsion is made,” Foley said. “A lot of people think you have to sit and watch it cure to let the water evaporate, but in tests seen by multiple DOTs from the northeastern U.S. to Texas that’s just not true.”
“Spray paving uses a higher application rate of emulsion and the heat from the hot mix breaks it,” Farrelly said. Essentially, the heat from the hot mix causes any moisture to immediately evaporate. “This higher tack rate creates an asphalt rich interlayer at the interface with the existing pavement, hence creating a better bond.”
With spray paving, Farrelly said, ambient temperature does not affect the application process any more so than any other hot mix application. “We spray in front of the screed,” he said. “The hot mix is 300+ degrees or so, so whether the ambient temperature is 40 degrees and rising or 110, the hot asphalt is what’s causing the emulsion to break.”
“Spray paving had proved to be as good, if not better, than the original way,” Foley said.
To start on any spray paving project, the crew first mills and preps the surface, removing any debris before paving can begin.
“Instead of trucks tracking emulsion onto the roadway and into communities, spray paving has allowed us to keep a cleaner jobsite and keep that roadway going out clean,” Foley said.
Their rate of application of the emulsion depends on whether or not it’s specified for on the job. If it’s a mill and fill, they’ll spray EBL at an application rate of .22 to .27. “Typically they don’t spec an EBL membrane, but we use a standard CRS or SS1 for conventional paving,” Foley said.
Choose a Spray Paving System
When it came time to purchase a spray paver for Austin Materials, Foley decided to attach the spray paving system on a conventional Cat paver.
“One of the largest benefits is the ability to remove and install the spray system itself, so if you invest in a paver and years later that paver no longer works, the spray system is still good,” Foley said. “The versatility of the machine versus others in the market is what I feel makes it fit our line of business and market. Ultimately the new innovations and progress with the systems have come a long way since the original Midland machines.”
He also added that the system is very user friendly, “from the start of the shift to the cleanup of the machine at the end of the shift. The majority of the system is easily accessible to do any preventative maintenance or issues. This really helps minimize down time.”
Although the system is removable, Austin Materials keeps the spray system on its paver 100 percent of the time. They try to use spray paving in any application they can.
“A lot of what we do is heavy highway, so we have no need to take the spray paver off,” Foley said. “We’re always looking for new ways to use it in our business.”
They’ve spray paved five different types of mixes, from dense graded mixes to superpave mixes to all performance mixes.
They’ve also used spray paving for large parking lots, but they don’t use it on smaller jobs because the spray system requires a material transfer vehicle. Austin Materials owns four material transfer vehicles, which they utilize on all jobs–requested, required, or not.
Although Austin Materials started spray paving to stay competitive, it’s easy to see that they’re now sold on the process.