Concluding Discussion The materials science of concrete provides a foundation for understanding, predicting, and possibly controlling its behavior. Our understanding of the fundamental relationships between structure and properties has been furthered by computerbased models simulating the development of the microstructure of hydrating cement paste and concrete. These models have advanced sufficiently to allow the prediction of transport and mechanical properties and even provide insights into the reasons for the behavior observed. The increasing emphasis on high performance concrete provides an incentive for further development of performancebased specifications. To make performance specifications truly practical, and to allow us to use them with confidence, we need to continue to improve the test methods that measure the performance and correlate them with field performance. Ideally, these correlations would not be merely statistical, but would be based on the underlying physical and chemical mechanisms. Some of the models used to predict field performance, for example for the purpose of comparing life-cycle costs of various alternative designs, are not solidly based on empirical data. Thus the use of such models is no better than extrapolation. Further work is needed to provide the necessary data. Another implication of the use of high performance concrete is that, as we seek to increase the strength or durability of the concrete, or the rate of construction, we observe seemingly new problems: a greater tendency to crack, for example. Although the basics of good concrete practice had been long established when the first edition of this volume was published in 1966, these basics are often slighted in the interests of meeting the constraints of schedule and budget. Concrete is a remarkably forgiving material, performing amazingly well even under the less-than-ideal conditions that prevail in the field. However, high performance concrete is much less “abuser-friendly”; it requires due attention to proper design and craftsmanship. Understanding the science behind the practice enables us to specify and enforce the right criteria to ensure the desired performance.
Posted on: Sun, 06 Oct 2013 11:07:07 +0000
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