EXPERIMENTAL PROJECT ON GROUT SUBSEALING IN ILLINOIS

This study conducted by the Illinois Department of Transportation evaluated the effectiveness of undersealing techniques using different grout mixtures in a test section of a highway in Illinois. The experimental project compared the performance of limestone-cement and pozzolan-cement (flyash) grouts, various admixtures, and the impact of different pumping pressures on pavement rehabilitation. The findings indicated that flyash grouts, particularly those mixed with superplasticizers or without any admixture, were superior in reducing pavement deflections at cracks and joints, showcasing higher strengths and better flowability compared to limestone grouts. Additionally, the study revealed that undersealing was more effective in areas with higher initial deflections, whereas it could increase deflections in areas with low initial deflections, suggesting that not all pavement sections are suitable for grouting. The application of grout did not depend significantly on pumping pressures within the range studied (69, 138, and 207 kPa). Long-term observations supported the initial results, endorsing the use of flyash grouts for effective pavement rehabilitation and undersealing operations. This research supports a more selective approach to undersealing, tailoring the choice of grout composition and application based on the specific conditions of pavement deflection. (Abstract generated by AI tool ChatGPT 4)