Aluminosis is a pathology of the concrete that floor joists suffer due to its manufacture with a type of aluminous cement that was used in beam factories, especially in the 1960s and 1970s. It was mainly used because it sets fast, so more joists could be manufactured by being able to deliver them earlier on-site, leaving space in warehouses for new shipments of material.
The joists with this type of cement may not present any anomaly and can be in our home without causing any problem. However, some circumstances can cause a chemical reaction of the cement that reduces the strength of the joist, with the consequent danger of collapse. There is a particular risk in humid areas and with industrialized environmental conditions. The damage is usually more significant in the upper floors since they are more exposed to the outside.
HOW TO KNOW IF A JOIST HAS ALUMINOSIS
The naked eye cannot distinguish between a joist affected by aluminosis or a joist that has received moisture and has oxidized its armour. The damages seem the same, and to determine if a joist has aluminosis an analysis must be carried out in a laboratory. If so, appropriate measures must be taken to replace the joist or to reinforce it adequately, for example, by placing iron girders below the affected joists. Furthermore, suppose an affected joist has been found in a building. In that case, it is necessary to monitor the rest of the joists in the entire building, even doing tests on false ceilings to verify that there are no more affected beams.
In Spain, there are many buildings affected by this "disease" known as "concrete fever", some of them as well known as the Vicente Calderón stadium in Madrid.
HOW TO REPAIR A BEAM WITH ALUMINOSIS
Not all cases are the same, but in general, a series of steps must be followed to repair joists with aluminosis.
STEP 1: SHORE THE AREA
Joists with aluminosis lose flexural strength, so the risk of collapse of the slab is real. It is important as soon as problems are detected to shore up the area while preparing the repair.
STEP 2: LABORATORY ANALYSIS
Concrete samples should be taken, and a construction laboratory asked to determine whether or not the beam has aluminosis, if so, it is advisable to carry out a thorough review of all the building beams.
STEP 3: CONCRETE REPAIR
To repair the concrete, one has to tap all the concrete in bad condition until one reaches the iron rod. If the rod has lost section, a possible structural reinforcement must be evaluated, which will be carried out in the next step. Existing rust on the rod will be removed by manual brushing, and a product will be applied that passivates the rust, preventing the rod from continuing the oxidation process. Finally, a structural restoration mortar will be applied, returning the joist to its original section.
STEP 4: STRUCTURAL REINFORCEMENT
On the assumption that in the previous point we determine that the beam's rods have lost section, we will conclude that the beam has lost resistance, so we must supplement the lost resistance through some reinforcement system.