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Investigation of Alternative Supplementary Cementing Materials (SCMs)

Project Summary

Supplementary cementing materials (SCMs) provide many benefits to concrete mixtures in terms of cost, long-term strength, and durability. Fly ash is the most widely used SCM in Texas. However, the dependence in Texas on fly ash for improving concrete performance is risky because the future availability of this material is questioned. Therefore, it is imperative to identify, screen, and thoroughly test alternative sources of SCMs for use in Texas concrete. There are many potential sources of alternative SCMs in Texas, including natural materials such as zeolites, diatomaceous earth, and calcined clays, and waste materials such as agricultural waste ashes and spent fluid cracking catalysts. In order to implement these materials into concrete mixtures, they must be thoroughly characterized and their performance in concrete mixtures thoroughly tested. The work aims to (1) identify all low cost, high availability sources of SCMs in Texas, (2) chemically and physically characterize them, (3) rapidly screen them for reactivity and performance, (4) determine optimum dosage amounts based on workability, reactivity/strength, and durability, and (5) test their performance in concrete mixtures. Particular attention will be paid to areas where SCMs traditionally have excellent or poor performance, including setting time, workability, early and long-term strength, drying shrinkage, and resistance to alkali silica reaction and sulfate attack. Because many of the lowest cost and most available materials that possess some pozzolanic reactivity may not meet current ASTM C618 Class N specifications, methods for enhancing their performance will be explored to enable their successful use. Further, because the performance of these materials may be different in concrete mixtures than currently used SCMs, guidelines for incorporating them into concrete mixture designs will be suggested.

Project Number

0-6717

Status

Completed

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