Alkali-Silica Reaction Induced Damage and Strength Degradation in Textile Mill

Alkali-silica reaction (ASR) has been recognized as a potential cause of concrete degradation in the world since the 1940s. In Pakistan, mega hydropower structures like dams, weirs constructed from aggregates extracted from a local river bed, exhibited different levels of alkali-silica reactivity over an extended service period. The concrete expansion potential due to such aggregates has been categorized as slow-reactive. Apart from hydropower structures, ASR existence has been identified in the concrete structural elements of a textile mill building which used aggregates extracted from the nearby river bed. The original structure of the textile mill was erected in the 80s with addition of a textile “sizing and wrapping” hall constructed in the 90s. In the years to follow, intensive spalling was observed in the structural members of the subject hall, enough to threaten the overall stability of the building. Limitations such as incomplete building data posed hurdles during the detailed structural investigation. The paper lists observations made while assessing the extent of damage and its effect on the building hall structure. Core testing and petrographic tests were carried out as per the ASTM standards for strength degradation analysis followed by its root cause identification. Results confirmed significant structural strength reduction due to the presence of ASR, which necessitated the formulation of an immediate re-strengthening solution. The paper also discusses the possible tracks of rehabilitative measures likely to be adopted for structural stabilization and to seize further concrete expansion.