Admixtures; Cement; Classification; Concrete construction; Fly ash; Materials; Pozzolan; Properties of materials
Supplementary cementing materials (SCMs) provide many benefits to concrete mixtures in terms of cost, long-term strength, and durability. Class F fly ash is the most widely used SCM in Texas, but its availability is dwindling. Given the importance of Class F fly ash as a means to improve concrete durability, it is important to find alternative materials that can maintain the high quality and durability of concrete in Texas. TxDOT project 0-6717: Investigation of Alternative Supplementary Cementing Materials (SCMs), completed in August 2014, identified sources of Class F fly ash alternatives that can be used in Texas concrete and developed best practices in testing these materials. Due to their higher availability and lower cost new sources of materials present better opportunities for Class F fly ash replacement than those initially tested. Implementation of the experimental protocols developed in project 0-6717 on these new materials will enable their use in Texas concrete. The objectives of this implementation project are to: (I) procure additional Class F fly ash alternatives not tested in the original project, including natural pozzolans, industrial byproducts. and reclaimed and remediated fly ashes; (2) chemically and physically characterize the materials; (3) determine optimum dosage amounts based on workability, reactivity/strength, and durability (4) test performance in concrete mixtures; and (5) make recommendations regarding their suitability for use in Texas. The testing will follow the recommendations from project 0-6717, with attention paid in particular to workability, admixture interaction, early and long-term strength, and resistance to alkali silica reaction and sulfate attack.