Investigating the efficiency of methods used to overcome early cracks due to heat of hydration in mass concrete in Uganda – case study (Karuma Hydropower Project)

Abstract

This research project investigated the efficiency of methods used to avoid early cracks that develop in mass concrete due to heat of hydration particularly on Uganda’s mass concrete projects. The objectives of the thesis were to find out the general methods used in overcoming heat of hydration during construction of mass concrete structures, to find out the nature of cracks that were discovered in the spillways and the causes of these cracks, to find out some of the methods used to overcome heat of hydration in Karuma hydro-power project and to identify how the methods used in Karuma H.E.P addressed thermal stresses evolved in the interior part of the mass concrete structure after early strength development. Data was collected using literature review, interviews with two laboratory attendants at the project site, and secondary data analysis to pursue the research interests. An attempt was made to understand the cause and extent of the deficiency that required repairs and to establish the efficiency of the methods, the parameters considered were cost to the client and contractor, time, how the method affects workability, and the specialization required for each method. Respondents were most aware of the methods used, their cost implications, workability of concrete for each method, and specialization required but for all the methods used, no thermal stress analysis was done to determine the heat of hydration evolved and a comparative stress analysis which is mandatory for every method. From the information collected, the researcher concluded these methods can only be efficient if a number of them are used for a single project. This should then be followed by determination of heat evolved because without it known, thermal stress analyses cannot be established