摘要: |
This project will develop guidelines for using waste concrete fines (and the associated wastewater) in concrete by developing methods to rapidly characterize fines samples and evaluating the performance of concrete using these recycled materials. Work in Stage 1 begins with a literature review on issues related to the use of recycled concrete fines. Subsequently, sources of recycled fines will be identified and samples collected and dried. The fines will be characterized after mixing them with water to create solutions/suspensions with 1 to 15% solids and their indices of refraction, pH, and conductivity will be determined. Mortar samples will then be prepared and their setting times and strengths will be measured for a range of recycled fines contents for fines with varying particle sizes. Correlations will be investigated and established to help develop a performance-prediction model for different recycled fines materials. This model will be used to develop guidelines for the use of recycled concrete fines in new concrete mixtures. In Stage 2, a laboratory-scale water recirculation system will be constructed incorporating in-line (continuous reading) sensors for measuring index of refraction, conductivity, and pH. Waste materials will be added to the recirculation system and evaluated using the in-line sensors. Concrete mixtures will then be prepared using the optimal blends of water from the recirculation system (containing waste concrete fines) and freshwater, based on both the in-line measurements and the characteristics of the desired concrete mixtures. An implementation plan for ready-mix concrete producers when upgrading their plants with in-line sensors will be developed along with instructions on applying the guidelines for use of recycled fines. |