Concrete Products

MAY 2017

Concrete Products covers the issues that attract producers of ready mixed and manufactured concrete focusing on equipment and material technology, market development and management topics.

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60 • May 2017 TECHNICAL TALK BY CLAUDIO ARATO The decline in coal for energy has reduced available fly ash supply to the concrete industry and generated a significant increase in finished product variability, which has led to a sharp rise in material costs for high profile projects such as One World Trade Center, New York City. The increase in coal combustion residuals (CCR) variability and decline in production has resulted in a shortfall in excess of 100 million tons of high quality coal ash stock. 3 Anecdotal stories abound about CCR imported from Asia to meet U.S. market demands over the last year. The American Coal Ash Association (ACAA) is now taking steps to quantify U.S. coal ash imports by commissioning an indus- try-wide survey with the results due this September. Why is there a need for CCR imports when there are nearly two billion tons in storage plus annual production? 4 The answer, simply, is consistency. Over the last several decades, there has been a consistent increase in the demand to beneficiate ash generated from coal-fired power plants. Simultaneously, there has been a steep decline in global coal-derived energy, from greater than 50 percent to less than 30 percent. 1 The coal-fired power industry has made excellent progress in quantifying and mitigating the perception of risk associated with CCR, generically "coal ash," as a pozzolanic high quality material for the production of high performance concrete (HPC). This is seen in the dramatic rise in the use of CCR in North America as the product Uniform particle size coal ash: Essential for future concrete applications At the heart of the SonoAsh process is the Sonicator, which enables the extraction and gradation of ASTM C618 fly ash from previously landfill- or impoundment-grade coal combustion residuals.

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