APPLICATION OF CHEMICAL CEMENT GROUTING IN NEW & OLD CONSTRUCTION REPAIR WORK

The deterioration of concrete and masonry structures due to cracking, void formation, shrinkage, aging, and environmental exposure poses serious concerns regarding structural safety, durability, and service life. Repair and rehabilitation techniques that restore structural integrity without demolition are therefore essential. Among various methods, cement–chemical nozzle grouting has emerged as an effective technique for crack sealing, void filling, waterproofing, and structural strengthening. The present study investigates the application and performance of cementitious and chemical grouts using the nozzle injection technique in old and new concrete as well as masonry structures. Experimental specimens consisting of concrete cubes and masonry prisms were prepared, and controlled cracks of varying widths were introduced. Cement-based grout and chemical grout (epoxy/polyurethane) were injected under regulated pressure through nozzles installed along the crack lines.The performance of grouted specimens was evaluated through compressive strength testing, water absorption measurement, and ultrasonic pulse velocity (UPV) analysis before and after grouting. The results indicated significant improvement in structural performance following grouting. Compressive strength increased considerably depending on crack width and grout type, while water absorption and permeability were substantially reduced. Chemical grouts demonstrated superior penetration and early strength gain in micro-cracks, whereas cementitious grouts proved to be economical and effective for larger cracks and voids. Comparative analysis between old and new concrete specimens revealed that older, more deteriorated specimens showed relatively higher performance enhancement after grouting due to improved internal consolidation. Masonry specimens exhibited enhanced bond strength and reduced seepage after treatment. The study concludes that cement–chemical nozzle grouting is a reliable and practical rehabilitation technique for both structural repair and durability enhancement. The findings provide technical insights for selecting appropriate grout materials based on crack width, structural condition, and economic considerations. Further research is recommended to investigate long-term durability performance and optimization of grouting parameters for large-scale field application.