Silica-free compound premiers for slab hardening, densifying

Utah-based slab treatment compound specialist Convergent Concrete Technologies bills its newest offering, the STRiON series, as a revolutionary new method of surface densification and hardening. Instead of silica, the formulation uses an ionic transfer process to disperse deep into concrete to make it more resilient, resistant to traffic, dustproof, easy to clean, and prepped for polishing. Applied to new or…

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Masonry, mortar tasks frame case for OSHA silica rule revisions

Sources: Construction Industry Safety Coalition, Associated Builders & Contractors, Washington, D.C.; CP staff

The 26-member Construction Industry Safety Coalition (CISC) has formally requested the Occupational Safety and Health Administration revise the Occupational Exposure to Respirable Crystalline Silica – Specified Exposure Control Methods standard (silica rule), thereby expanding compliance options and recognizing sub-threshold dust levels typical of masonry sawing and mortar mixing.

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Prestress Services challenges OSHA silica, respiratory exposure claims

Sources: Occupational Safety and Health Administration; CP staff

Prestress Services Industries LLC (PSI), Columbus, Ohio-based producer of architectural or structural precast for building and transportation markets, will contest Occupational Safety and Health Administration-proposed penalties of $158,500 before the Occupational Safety and Health Review Commission. 

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OSHA revisits principal reference in silica standard for construction

Source: Occupational Safety and Health Administration 

OSHA is soliciting industry perspective and comments on Table 1 of the agency’s Respirable Crystalline Silica Standard for Construction through October 14. Officials seek information on a) additional engineering and work practice control methods to effectively limit exposure to silica for listed equipment and tasks; and, b) other silica-generating construction equipment and tasks that the agency should consider adding to the table.

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NRMCA publishes silica regulations compliance guide

Sources: National Ready Mixed Concrete Association, Silver Spring, Md.; CP staff

NRMCA Executive Vice President, Compliance & Operations Gary Mullings and Vice President, Compliance & Regulatory Affairs Kevin Walgenbach review raw materials, plant conditions, housekeeping measures, worker protection, exposure monitoring and best compliance practices in “Guide for Silica Regulations and the Ready Mixed Concrete Industry.”

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HPC mix designs heed laser tunnel aluminum, magnesium, silica sensitivity

Tunnel max crop

LafargeHolcim Ltd. unit Holcim Deutschland formulated a series of high performance concretes for elements lining a 3.4-kilometer tunnel housing the world’s most powerful X-ray laser. Located near Hamburg, Germany, the European XFEL generates extremely intense X-ray flashes researchers from around the world use to map atomic details of viruses, film chemical reactions, and study the processes in the interior of planets.

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Silica dust exposure protection carries the day at World of Concrete 2017


World of Concrete 2017 evidenced a mid-year enforcement timetable for the Occupational Safety and Health Administration’s new respirable crystalline silica exposure threshold covering construction sites and general workplaces. Leading the charge for compliance at the January 17-20, Las Vegas gathering were exhibitors of sawing and drilling equipment—loaded with dust collection devices—along with peers promoting cementitious material conveying, handling or dispensing devices with which silica dust can reach agency-reduced levels.

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OSHA, NIOSH flag silica in manufactured stone

11 Hazardi 300

A joint Occupational Safety and Health Administration and National Institute for Occupational Safety and Health Hazard Alert defines dust control measures to protect workers from significant crystalline silica exposure during manufacturing, finishing, and installing natural and manufactured stone countertops, leading types of which bear 60–95 percent silica content.

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Sizing up nano-scale materials

For the third year in a row, we visit a pavement project VCNA Prairie Material helped convert from all asphalt to partial (base slab) or 100-percent roller compacted concrete. More than a routine switch, the Maryhill Cemetery maintenance shop (pages 28-31) marks the commercial debut of RCC Surface Pro, a silica agent emanating from the field of nanotechnology, where particles are measured in billionths of a meter.

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FHWA’s new Alkali- Aggregate Reactivity Facts Book

From the Federal Highway Administration’s Focus newsletter… Alkali-aggregate reactivity (AAR) can occur in concrete structures and pavements as both alkali-silica reaction (ASR) and  alkalicarbonate reaction (ACR). FHWA’s new Alkali-Aggregate Reactivity Facts Book (Pub. No. FHWA-HIF-13-019) discusses both types of reaction but concentrates on ASR, as cases of ACR are more limited.

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