Evaluation of Fresh State and Mechanical Properties of Cementitious Grouts

Abstract

Many construction activities, such as prestressed cable ducts (internal or external) for structural elements, masonry and RCC structure repair and reconstruction, shoring and soil stabilization, geotechnical applications, and so on, use cement grouting. These grouts comprise basic elements such as cement, sand if used, water and, possibly, admixture(s) along with non-shrink chemical admixtures. They exhibit higher compressive strength compared to other materials. Varying the mix proportions and dosages of the different additives used can easily change the rheology and characteristic properties of the grout. Grouting of cable ducts of prestressed structures to fill in the voids or gaps between the ducts and prestressing strands is a large-scale application of cement grouts. Damages such as corrosion and rupture of prestressing tendons/strands due to insufficient grouting and/or chloride attacks from airborne salts, use of de-icing salts, or use of sea sand in the concrete can cause these structures to deteriorate in strength and durability. In such situations, there is a possibility that this sea water or de-icing salt may penetrate into the ducts, thus corroding the prestressing strands/cables. The entire structure's tensile load carrying capacity is mainly dependent upon the tensile stress carrying capacity of cables/strands. As a result, the alkaline/passive layer, i.e. grout, must be thoroughly mixed and injected into the ducts in order for it to achieve the desired properties after hardening. Bleeding occurs when using pure cement grout, reducing the w/c ratio but increasing strength. As a result, admixtures such as Cebex 100, Cebex 200, and Cebex EN or equivalent will be added to the pure cement grout to improve its rheological properties such as bleeding, compressive strength, and durability properties such as shrinkage and permeability, and their properties will be investigated. Understanding the performance of cementitious grouts based on dosage and other additives at a major River Bridge Project in Goa is the goal of this research.