A structural defect caused by the conversion of metastable calcium aluminate hydrates into a more stable but denser form. This internal volume change increases the porosity of the concrete, dramatically reducing its compressive strength and leaving the reinforcement vulnerable to corrosion. It is primarily associated with historic use of high-alumina cement in damp, warm conditions.
Heard on the job
The structural assessment flagged aluminosis in the precast joists, so they need immediate shoring.