Rock Products - The Leading Voice of the Aggregate Industries.
  • Picking a Perfect Primary

    Impact Crusher at an APAC-Kansas City Quarry has the Operation Primed for Success. By Mark S. Kuhar Read More
  • In-The-Field Dreams

    At R.E. Pierson’s Stone Yard in New Jersey, W.S. Tyler conducted Specialized Field Tests for a Number of Aggregates Producers. By Mark S. Kuhar This is the second in a new series of personal accounts called “Quarry Stories,” written by the editor of Rock Products, bringing you perspective and insight gleaned from more than 20 years of covering the equipment, technology, plant operations and people that make the aggregates industry great. –Ed. Read More
  • Rock to the Top

    Rock Products Presents the Top 25 Construction Aggregates Producers. Following are the top 25 aggregates producers in the United States, according to information released by the U.S. Geological Survey. This information is based upon 2012 production and does not take into consideration mergers and acquisitions that have occurred since that time. – Ed. Read More
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Rock from the Road: Blog and Travelogue

article thumbnailAugust 1, 2014 – Now this is an innovative idea. The federal government’s U.S. Patent and Trademark Office has issued to Mellott Company the federal service mark registration for “CrusherFax by Mellott Company.”

Prime-Time Products

article thumbnailKlϋber Lubrication introduced Klübertemp GR AR 555, a multi-purpose lubricant offering exceptional corrosion protection and high evaporation stability, according to the company.

Rock Stars

article thumbnailMcLanahan Corp. CEO Sean McLanahan was recently recognized for his community involvement by Junior Achievement of Western Pennsylvania. Sean received the Paul I. Detwiler III Achievement Award for his significant contributions to the social, economic, educational and cultural development of the region.
More inRock Stars  

Manufacturers in Focus

article thumbnailTerex announced that Kemper Equipment Inc. has been named its dealer in the states of Delaware, New Jersey, Maryland and Pennsylvania for the Terex Cedarapids and Terex Canica crushing and screening equipment lines of Terex Mineral Processing Systems (MPS). 

People on the Move

article thumbnailJeff Kaveney, Eriez manager-product marketing and administration, announced that Ray Spurgeon has assumed the role of product manager-metal detection. Spurgeon will now oversee and handle metal detection inquiries, OEM and major account growth, orders, product development and improvements, marketing, training and sales forecasts as well as other functions.

Latest Digital Issue

Off-Highway Diesel Prices


The national estimated average price-per-gallon for off-highway diesel fuel as of July 29 is $3.587. That is lower than the previous comparison price-per-gallon of $3.637.

Limestone Cited as Benefit to Green Concrete


By Mark S. Kuhar

Adding limestone powder to “green” concrete mixtures – those containing substantial amounts of fly ash, a byproduct of coal-burning power plants – can significantly improve performance, according to researchers from the national Institute for Standards and technology (NIST) and the Federal Highway Administration (FHWA).

The promising laboratory results suggest a path to greatly increasing the use of fly ash in concrete, leading to sizable reductions in greenhouse gas emissions, energy use, construction costs and landfill volumes. Global production of cement for concrete accounts for 5 to 8 percent of human-caused greenhouse gas emissions, according to NIST.

Currently, fly ash accounts, on average, for about 15 percent of the binder powders in the ready-made concrete used in the U.S. To produce a more green concrete, NIST is researching new material combinations and procedures that could help the industry use fly ash to routinely replace 40 to 50 percent of the ordinary portland cement (OPC), the main binding and hardening agent in concrete.

Because of delays in setting times and questions about its strength in the first few days after application that both “impact its constructability,” said NIST chemical engineer Dale Bentz, “green concrete has been a tough sell in large parts of the construction industry.” However, Bentz and his FHWA colleagues found that a “judicious combination of fine limestone powder” can help to put these concerns to rest.

So-called high-volume fly ash “ternary” mixtures (including some limestone) that replace between 40 percent and 60 percent of the cement portion not only set at rates comparable to those for typical concrete, but also were superior in terms of key properties.

Initially, the strength of the green concrete mixtures after 28 days slightly lagged that of concrete without any fly ash. However, the team was able to tweak their fly ash-limestone-OPC mixture to overcome the gap, primarily by lowering the water-to-powder ratio and switching to a different standard composition of OPC (ASTM Type III).

Today, global production of OPC totals about 3.5 billion metric tons (3.85 billion tons) annually. Generation of each ton of OPC emits about a ton of carbon dioxide into the atmosphere.

Greater use of high-volume fly ash mixtures could significantly reduce this environmental burden and, at the same time, reduce costs for concrete construction, said Bentz.

For Bentz and his team, the next research challenge is to test their limestone-enhanced mixtures in the field, where curing conditions can vary. A later report will be issued with additional findings.