Study on Cementitious Grouts

The most commonly adopted material for grouting nowadays is Portland cement. It is used in many applications such as grouting of prestressed cable ducts, stopping major water inflows, rehabilitation of masonry and RCC structures and geotechnical applications. It is basically a mixture of cement, sand (if used), water and, possibly, admixture(s) along with non-shrink additives. Their properties such as fluidity, setting time, stability, strength and durability can be easily modified by adding various types of chemical admixtures. The major application of cement grouting is for prestressed bridge construction site as the grouting work involved is huge for filling the voids or gaps between post-tensioning cable ducts and prestressing strands. Durability of these structures is mainly dependent upon the level of corrosion protection offered to these structures as they are very much susceptible to corrosion especially in marine environments thus degrading strength and durability of stressing tendons. Also, the w/c ratio of the grout is the most important factor contributing significantly to the strength of the grout. Use of lower w/c ratios requires incorporation of certain additives so as to maintain the appropriate rheological properties of the grout. Therefore, to protect the prestressing strands from effects of corrosion and also to ensure complete filling of the cable ducts, enough precautions are required to be taken during entire grouting procedure from start to end. Grouts prepared with pure OPC bleeds reduce the w/c ratio thereby increasing the compressive strength. Presence of admixtures in the grout plays a vital role as they help in the production of more durable grouts with enhanced rheological and mechanical characteristics. Therefore, in this study certain admixtures like Cebex 100, Cebex 200 and Cebex EN will be added to the cement grout to modify their properties, and their characteristic behaviour will be studied. This study aims at understanding the performance of cementitious grouts based on the dosage of certain additives at a major River Bridge Project in Goa.