By Cody Preston
From the time I was a young child riding out to the job site with my father and watching crews pave, I have been intrigued by the process of taking concrete and turning it into a road, runway, or taxiway. Now, some 35-plus years later, I am even more impressed as I look back at the changes the industry has made to improve concrete paving, especially here in Utah.
Dowel Bar Placement
One of the earliest improvements came in the form of dowel bars. Along with transverse joints, these were just starting to be introduced during my childhood. Dowels help transfer the vehicle loads from one concrete panel to the next, improving the smoothness of the pavement even as it ages.
If you have ever driven down an older concrete road, you have most assuredly felt annoying bumps every 15 to 20 feet or so. With the introduction of dowel bars, these bumps can now be minimized over time. This not only helps with smoothness but with the overall durability of the pavement.
Over the years, the location of these dowels in the pavement has changed as we continue to learn what does and does not work. In a lot of the older pavements, dowel bar retrofits are being done to pavements that were originally constructed without them.
Some of the early mix designs of concrete were very basic: cement, fly ash, water, sand, and one general size of rock, perhaps with some admixtures to provide some workability. Over time, the concrete paving industry has worked, and is still working, on optimized concrete mixes.
These mixes now can include up to three or four different rock sizes. This helps fill the space between the rocks with smaller rocks, resulting in more consistent and durable concrete.
Advancements in admixtures are helping to improve workability while maintaining or improving durability. It has been fun to see and hear about improvements to concrete mixtures over the last 35 years.
With the depletion or inaccessibility of our natural resources, and as more environmentally friendly types of cement are becoming the new standard, the use of recycled materials in concrete is increasing in traction across the country. The basic ingredients haven’t changed; we are just finding ways to use those ingredients in optimal ways.
The equipment used today has come a long way over the last 35 years. The older pavers had some hydraulic levers and some manual crank adjustments. Today, we have pavers with onboard computers that communicate with total stations, and, in some cases, with other equipment on the job.
These new concrete pavers have now gone to stringless or smart paving. The elimination of stringline along the side of the paving lane has increased access to the paver for the trucks hauling concrete and made the overall process safer.
This takes the place of the old sledgehammer, stakes, and stringline that once controlled the elevation and alignment of the old pavers.
Concrete batch plants have made significant improvements over the years, increasing production speeds and batching accuracy. This newer technology allows for better productivity and control as well as diagnostics when something goes wrong.
Maturity meters have also been a meaningful development in concrete paving. The process begins with developing a maturity curve for the specific mix design of concrete in use. Once that curve is developed, a sensor is placed in the side of the concrete slab with a data reader. This provides real-time measurements on the strength of the slab of concrete, helping to improve efficiencies throughout the project.
These are just some of the adjustments and innovations that have taken place in concrete paving over the years—changes that have improved the overall smoothness of concrete pavements in worthwhile ways.
As an industry, we continue to improve the concrete roads, runways, and taxiways that each of us uses every day, making them safer, smoother, and more durable. I am amazed at the improvements that have taken place through my lifetime, and I look forward to seeing what innovations come to concrete paving over the next 35 years.