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From page 86... ...
Summary of Findings Literature Review The use of SCMs as a replacement for a portion of the Portland cement content in well proportioned concrete mixtures has been shown to improve the fresh and hardened properties of the concrete. SCMs also contribute to the reduction of concrete infrastructure's carbon footprint, allowing agencies to achieve not only improved concrete strength and durability properties, but also sustainability benefits associated with the judicious use of cement in concrete mixtures used in structures and pavements.
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From page 87... ...
Prior to ASCM approval and use, agencies would assess the characteristics and variability of the ASCM, evaluate the concrete produced with the ASCM, evaluate the performance of the ASCM or system containing the ASCM, assess the availability the ASCM, assess the uniformity of the ASCM's production and the consistency of its properties, and ensure implementation of appropriate measures in concrete mixture design and construction practices to mitigate potential negative impacts from the ASCM's use. Survey Results A survey of 25 questions was sent electronically to all 50 state DOTs and those of Puerto Rico and the District of Columbia.
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From page 88... ...
The responding DOTs reported allowing varying combinations of SCMs in ternary mixtures: fly ash and slag cement, fly ash and silica fume, slag cement and silica fume, and NPs and slag cement. Also, seven DOTs out of 39 that responded use quaternary concrete mixtures for both bridges and pavements, while two use these mixtures exclusively for bridges and other structures.
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From page 89... ...
This approach helps accommodate the slower strength gain of many SCM mixtures while still achieving the benefits associated with lower concrete permeability. For mixture design approval, 28-day strength test results are still required in concrete mixtures with and without SCMs, MnDOT has occasionally allowed HPC bridge deck mixtures up to 56 days to meet strength requirements.
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From page 90... ...
• The status of fly ash availability should be monitored, as should how the shortage in fly ash is changing the specifications of state DOTs and having an impact on developing guidelines, based on new and evolving ASTM tests and specifications, for approval of harvested ash, NPs, and ASCMs.
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