Forty-eight years ago when Sanders Saws, Honey Brook, Pa., was founded, the world of construction was a different place. The company was among the first to develop the hot-pressed process. When Bob Priest purchased the company in 1983, the technology for performing the work on concrete surfaces showed lots of promise but needed a firm hand.
Priest developed the Ricklan Sanders T joint, one blade designed to induce cracking and form a sealant reservoir in one pass. Unlike traditional joint sawing, the RST blade gained a reputation in the industry eliminating the widening operation and reducing sawing time, dual crews, joint washing and sandblasting for fast-track paving.
Just when things were getting good, they got better. Priest later inaugurated The Next Generation one pass blade, dubbing it SITS for Sanders Interlocking T System.
So why did the company need SITS when they already had RST?
Joining the cores
In certain applications, the RST outer diameter (OD) would wear out before the inner diameter (ID). The reason for this phenonemon is that the blade turns at a given RPM, but having two working diameters the outside diameter covers more surface feet than the smaller inside diameter at the same RPM. Sometimes, the bond on the outside would be changed to a harder composition to compensate for the wear on the inside segments.
"We would have to hit the right combination for each application each time," said Romey Messina, vice president of manufacturing and product development at Sanders Saws. Ideally, the OD and ID should wear at the same rate. With an RST-2 for a given diameter and reservoir depth, if the specifications changed a new blade would be needed to accommodate the new specs.
"The SITS consists of three elements: a center core and two inner cores, interlocking to create a single blade," said Priest, president and CEO of Sanders Saws. "This versatile new system enables the contractor to consume all the diamonds for the best return on his investment."
A significant advantage of the SITS is its interchangeable center and inner cores. Unlike the RST where the OD would wear before the ID, the new SITS’s interchangeable cores can provide for harder or softer bonds, deeper or shallower kerf and narrower or wider reservoirs applications.
"With the SITS, we could start out with the same bond on the outside and inside diameter and notice which was wearing prematurely," said Messina. "If it was the OD we could change the matrix to meet the wear rate on the ID so that they would wear uniformly at the same rate," he said.
A step fast
The SITS was field tested in several locations. One of the sites was a Central Atlantic, Aberdeen, Md., project on Rt. 40 in Elkton, Md. The aggregates in Maryland are medium soft limestone in approximately 60% of the state, and the balance of the state is medium hard river gravel.
Although the SITS passed its first test, "we came back and made some adjustments to the bond and diamond size to give us a faster, freer cutting blade," said Messina. "Because we are removing a greater mass in a single pass, the matrix needs to be slightly softer than normal green sawing conditions," he added.
The SITS strong performance at that site encouraged Central Atlantic to take the blade on other roads.
"We have used the SITS on several repair projects in Cherry Point, N.C., at the Marine Corps Air Station and also on I-26 in Ashville, N.C.," said John Depman, president of Central Atlantic. "It allows you to do two steps in one by doing the green sawing and widening simultaneously. The most important part of it was that you didn’t have to set traffic for the second step, you didn’t have to do a traffic control step, eliminating maintenance and traffic cost."
The SITS second field test was on I-75 in Kentucky.
"There was a concrete pavement restoration project where the contractor was pulling out large segments of the highway and replacing them with new concrete patches," said Messina. "The aggregates there are medium soft limestone and sandstone. Along the Ohio River there is medium hard quartzite river gravel. We tested a new blade there and changed the ID to a softer bond than the outer diameter because we were removing a much wider section and needed to cut the hard river gravel," said Messina.
Don Shonyo, concrete paving superintendent at PCI, Progressive Contractors Inc., Osseo, Minn., said that their company’s earlier use of the first generation one pass blade convinced him of the usefulness of the SITS. On a fall 1992 project the RST blade made itself useful, according to Shonyo.
The project consisted of 11 miles of 27-ft-wide, 15-ft joint spacing using recycled gravel material. The joint design was 3/8 in. x 1 in. x 2 in.
Rainy weather conditions prohibited use of the median as a haul road, which left only the shoulder to run PCI’s trucks. Using a span saw and RST-1 blades, the joints were green sawed and widened at the same time, leaving the shoulders clear of any saw equipment, water trucks and other equipment before they started paving the following morning.
"The joints were sealed with silicone within 48 hours. After seven days curing time our trucks were allowed to use the new road with no damage to the joints," said Shonyo.
Grinding saw teeth
Widespread promotion of the new SITS was delayed because "we already had the RST which was working successfully in numerous locations all around the country and because of the large dollar amounts already invested in the RST program," said Messina.
It takes years of experience for a diamond blade manufacturer to know how to build a blade for the many combinations of aggregates.
"What Priest does that some others do not do is put experienced people in the field to check the product or the saw blade they are selling to us to make sure it is the most efficient blade to cut the aggregate that we are working with," said Larry Kincaid, vice president and quality control engineer at Hi-Way Paving Inc., Hilliard, Ohio.
"The step blade we used for the first time in Indianapolis was at the Eagle Air Hub, a federal post office job at a new air postal facility," said Kincaid. "We were fortunate to win the contract. It was a tight job that we had to have opened and operational quickly. We used the step cut blade there to actually eliminate one full phase of work. We gained about 20 days of production to saw and seal the job. Time is important because if it is something like the postal system, the government sets store on getting those facilities finished on time because it’s not just serving a few, it’s serving the whole nation."
Val Riva, president of the American Concrete Pavement Association (ACPA), where Priest serves on the executive committee for legislative affairs, said that Priest’s research and development could best be underscored by his work to promote concrete pavement restoration (CPR).
Priest has long been a proponent of CPR using diamond grinding technology.
Tony Ricci, chief bridge engineer on the Massachusetts Turnpike Authority’s Central Artery/Tunnel project, said that they have had occasions to use diamond grinding.
"In one particular area, because the existing viaduct was next to housing, we experienced vibrations from heavy traffic that bothered people," said Ricci. "We needed to come up with a solution to mitigate this vibration. We had to take readings that would give us a family of vibration curves to change the resonance. We said, ‘Let’s try grinding.’ It was in pretty poor shape being a bridge built in the ’50s with wavy wearing surface because of repeated repairs. The reading that we got originally was reduced significantly so we have had little to no complaints since the diamond grinding."
Riva said that ACPA’s non-profit research group, the Innovative Pavement Research Foundation, was formed to do research on concrete pavement. "The research is conducted to find ways to put down concrete even faster, to make it so that we could repair it easier and find ways to economize to make it less costly to fine-tune an already good product.
"Congress has passed the TEA-21 bill that provides for close to $200 billion over the next couple years for road and bridge improvement. Priest has been a leader in pushing CPR, putting it on legislators’ agenda so that they can understand their options."
Sohilia Bermanian, assistant chief materials engineer, Nevada Department of Transportation, said that diamond grinding is one of the best strategies for the taxpayer’s money.
"We did I-15 through Las Vegas. The concrete was very old, very rough and by using diamond grinding that was the best thing that we could do."
Priest’s continued research for technical solutions to produce the types of high-performance bonds, segments and blades has begun to earn the patented SITS blade a place in the market.
"Everyone is trying to build better and bigger and faster machines," said John Sterner, production manager for Pavement Specialist Inc., Roanoak, Texas. "The time that we have to work on airport runways is as little as they can give you it seems. It’s in the middle of the night and they want a lot done."
Kincaid said that they also have used the SITS at the Pittsburgh International Airport.