Concrete Products Online reported on a new Federal Highway Administration (FHWA) Tech Brief titled “Supplementary Cementitious Materials—Best Practices for Concrete Pavements” (FHWA-HIF-16-001). State highway agencies (SHAs) and others charged with construction and maintenance of roads and bridges expect one key property from concrete: durability. Meanwhile, service demands placed on concrete structures continue to increase, along with expectations for reduced environmental impact and lower initial and lifecycle costs. To produce concrete mixtures that satisfy these demands, engineers increasingly turn to SCMs as part of the solution.
This tech brief describes common supplementary cementitious materials (SCMs):
• Highlights the benefits and drawbacks of fly ash, slag cement, silica fume, and natural or alternative pozzolans for highway-grade concrete
• Outlines how transportation agencies approach increasing service demands on concrete structures
• Outlines expectations for reduced environmental impact plus lower initial and lifecycle costs
• Discusses recent trends that may affect the use of SCMs during the foreseeable future
• Discusses hydraulic and pozzolanic activity
• Discusses the chemistry, specifications and performance characteristics of fly ash, slag cement and silica fume; plus, ternary mixtures, where two or more SCM or binder materials join ordinary portland cement in concrete mix designs
• Examines how availability issues of the main SCM are opening the door to:
a) Natural pozzolans … including some diatomaceous earths, opaline cherts and shales, tuffs and volcanic ashes, pumicite, and various calcined clays and shales
b) alternative SCM, defined as inorganic materials that react, pozzolanically or hydraulically, and beneficially contribute to concrete strength, durability and workability, but do not meet ASTM or AASHTO specifications for conventional SCM
To download the seven-page pdf of the Brief, please go to: https://www.fhwa.dot.gov/pavement/concrete/pubs/hif16001.pdf.
“Supplementary Cementitious Materials—Best Practices for Concrete Pavements” was published with oversight of Sam Tyson, P.E., FHWA Concrete Pavement Engineer and authored by Lawrence Sutter, Michigan Technological University Professor.