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Concrete paving has come a long way since the early 1900s. Whilst high durability pavements were able to be hand-placed 100 years ago, concrete pavements today are produced faster, stronger and more cost efficiently using slipform pavers. We’ve come a long way. Whilst acknowledging that the right pavement is needed in the right place, modern slipformed concrete pavements have been through an evolution in design and specification, and now represent the best value for money durable pavements they have ever been. This presentation by Peter Carson is designed to take you along some of that journey.
The benefits of replacing a proportion of cement with fly ash in concrete mixes have been well understood for many years, particularly in the mitigation of alkali silica reactions. In pavement concrete mixes, however, the properties of fly ash can often play havoc in controlling the amount of air in the concrete which is usually required for both protection against freeze/thaw expansive cycles during winter months as well as aiding slipforming processes. Bruce Perry will focus on a novel means by which the presence of activated carbon in fly ash can be “de-activated”, thereby minimising its deleterious effects on the efficiency of AEA’s in air entrained pavement concrete mixes. He will also propose that a relaxation in the permitted coefficient of variation (CV) in loss on ignition (LOI) could allow many thousands of “extra” tonnes of fly ash to be used in both normal and air entrained pavement concrete mixes to replace cement, thereby going someway to alleviating the current shortages of fly ash, particularly in NSW.