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Executive Summary

Cement manufacturing process accounts for approximately 5-7% of global CO2 emission and has significant adverse impact on a wide range of sustainability issues including climate change, pollution and resources depletion. Increased awareness in this decade on the significance of developing sustainable and environmentally efficient infrastructure materials renewed the interest in exploring Cement Free Concrete (CFC) (also known as Alkali Activated Concrete or Geopolymer Concrete). This low energy, sustainable concretes are developed by activating fly ash or ground granulated blast furnace slag using commercially available alkali such as sodium hydroxide or sodium silicate hydrate (waterglass). However, the lack of studies and experimental data on optimum mixture proportioning of alkali activated concretes, especially for pavement application, is a serious limitation in designing and developing concretes of appropriate specifications in the field. In the proposed study, an experimental characterization to evaluate the viability of alkali activated CFC for pavement and bridge deck applications, by activating Class C fly ash or slag is recommended. The major focus of the proposed study is to identify the optimal proportion of an activator or a combination of activators that can provide adequate strength without requiring any thermal curing, making the CFCs even more energy efficient and user friendly. In addition to the optimum mixture proportion, the fresh properties (workability, setting time and heat of hydration), hardened properties (compressive, tensile, flexural strengths, modulus of elasticity and stress strain behavior), and durability performance (resistance to drying shrinkage, chloride ion penetration, alkali silica reaction) will be evaluated in comparison to the performance of a typical concrete mixture proportion that New York/New Jersey DOT use for the pavement and bridge deck construction.

Intellectual Merits of the proposed study is that it will provide deeper insight into the behavior and performance of alkali activated concrete, especially for pavement and bridge deck construction applications. The experimental data obtained through this research may contribute to develop standards and guidelines that may promote the usage of this greener concrete by the DOTs, especially in Region 2.

The Broader Research Impact:

The energy and environmental benefits of replacing portland cement concrete with CFC, even by a small percentage, is going to be very significant. The development of energy efficient and environmental friendly CFC is expected to benefit not only U.S.DOT’s Region 2 but the entire nation as well. The topic of the proposal is timely and matches well with the theme of the center “Planning and Managing Regional Transportation System in a Changing World” and the USDOT strategic goal Environmental Sustainability. one graduate and one undergraduate students will get trained in the area of sustainable material development for infrastructure application through this project, preparing them to address such problems in their career.