Concrete is one of the most versatile building materials and has facilitated industrial growth in the last century. However, it is difficult to get rid of concrete waste when concrete buildings are demolished. Crushed old concrete is recycled as aggregates in highway pavements but it is not used in buildings and bridges because of uncertainties of performance of new concrete. If crushed old concrete can be recycled in new building construction it would help in getting rid of waste and preserve natural riverbed rocks. This project will pursue research in classifying old crushed concrete for its use as aggregate in new concrete for buildings and bridges. Properties such as strength, durability, long-term deformation will be determined for concrete made with recycled concrete. As the nations infrastructure goes through upgrading, the volume of available waste concrete will increase. Use of this waste concrete in new concrete will reduce environmental impact of storing the waste and preserving natural environment of riverbeds.
Structural concrete made with recycled concrete aggregates can have significant variability in the behavior of buildings and bridges regarding deformations, creep and durability. The project will pursue experimental and analytical research to seek answers to these questions: (1) what are the economic and environmental benefits of recycling concrete in structures? (2) what are the long-term service load and design load performances of structural members, including prestressed concrete members? (3) how do recycled concrete aggregates affect durability? and (4) what modifications, if any, need to be made to crushed concrete to enhance performance of new concrete? The project will assess mechanical properties of concrete made with crushed concrete as aggregates. Also, beams and columns made of recycled concrete will be tested in laboratory to establish performance of structural components. Ultimately, the project will develop performance-based requirements, mix design guidelines, acceptance tests, and structural design/analysis/construction guidelines to achieve acceptable performance of concrete members using recycled concrete aggregates.