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  • KICKING MORE APP

    A Look at Mobile Apps With Equipment and Technology in Mind.  By Josephine Smith Read More
  • The Bar Has Been Raised

    There May Be Better Ways To Help Adults Learn And Retain Information They Gain From Educational Or Training Events. By Joseph P. McGuire and Billy Snead   Read More
  • Rocking the Volcanoes

    A Contractor Drills Rock in Hawaii with a New Generation of High-Tech Rigs. By Mark S. Kuhar   Read More
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Rock from the Road: Blog and Travelogue

article thumbnailSept. 23, 2014 – Big cheer for Pennsylvania for innovative infrastructure financing. More than 500 of Pennsylvania’s worst bridges will be replaced under a program that uses a private consortium to finance, design and build the bridges and then maintain them for 25 years. 

Prime-Time Products

article thumbnailChevron Products Co. held a media webinar to introduce Delo 400 SD SAE 15W-30, a severe duty diesel engine oil that is engineered to address major shifts in on- and off-highway applications.

Rock Stars

article thumbnailLafarge North America's Presque Isle Quarry in MIchigan celebrated its 60th anniversary by hosting its first annual Stoneport 5K Quarry Run/Walk on Aug., 28, 2014, to benefit the Cancer Center at Alpena Regional Medical Center (ARMC). 
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Manufacturers in Focus

article thumbnailABB announced at the UN Climate Summit in New York that it is joining the United Nations Environment Program’s global action on improving appliance and equipment efficiency. The company will provide expertise on energy efficient motors and transformers to help governments devise policies that accelerate energy savings.

People on the Move

article thumbnailBruno Roux was appointed president and chief executive officer for the Eastern Canada business unit of Lafarge Canada Inc. In his new role, Roux will serve as Lafarge's senior leader for all market areas and product lines in Ontario, Quebec, and the Atlantic provinces. Roux will also join the Board of Directors of Lafarge Canada Inc.

Latest Digital Issue

Off-Highway Diesel Prices


The national estimated average price-per-gallon for off-highway diesel fuel as of Sept. 23 is $3.508. That is lower than the previous comparison price-per-gallon of $3.547.

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.