Preliminary Optimization of Concrete Paving Mixtures for Sustainability and Performance

Greater sustainability in concrete construction projects generally requires higher replacement of portland cement clinker-based binder materials with byproduct supple-mentary cementitious materials (SCM’s). There may be serious constructability-related performance side effects of such concrete mixtures, however, including delayed setting, slower strength gain, and increased sensitivity of the mixture to changing temperatures. Related impacts for paving applications may include placement and finishing issues, cracking, surface profile and durability concerns, and various other quality and scheduling implications. Mix designs often require more aggressive chemical admixture use and performance side effects are difficult to predict and manage. A protocol is presented for the evaluation of materials and preliminary optimization of proportions that can help maximize practical SCM use in concrete paving mixtures while approximating the performance of traditional mix designs. An approach using simple thermal profile testing of paste mixtures in the lab is presented and used to show how these influences can be understood and managed.