What it is, in plain English

Cement is the glue in concrete: it binds sand and gravel and gives the mix its strength. High-alumina cement is made by heating aluminium- and calcium-rich materials to very high temperatures, and its selling point is speed: a precast part such as a floor joist gains in hours the strength that Portland cement reaches at 28 days.

The catch is described in the instruction itself (RC-16, Royal Decree 256/2016): the compounds it forms as it hardens change over the years, a process engineers call conversion, and the concrete can lose strength. How much depends heavily on the water used in the mix and the temperature in the first 24 hours.

When that deterioration progresses and affects the structure, it is known as aluminosis. Having high-alumina cement does not mean having aluminosis: they are two different questions, and only a look at the structure answers the second.

Is it still used today?

Yes, with conditions. Spain's 2021 Structural Code (Royal Decree 470/2021) requires a special study, case by case, explaining why it is used before it goes into structural concrete. RC-16 also notes that, with suitable aggregates, it makes refractory mortars and concretes.

What worries buyers is not new construction but the precast joists of older buildings, put up when its use was far more widespread.

Why it matters if you are buying

If a building's joists are made with high-alumina cement and have deteriorated, the usual fix is to strengthen the floors. That work belongs to the community of owners (comunidad de propietarios) and is shared out by each flat's ownership quota, so it can turn into a special levy (derrama) for every owner, including you once you buy.

Before you sign the deposit contract (arras), find out three things: the year of construction, whether the latest building inspection mentions cracks or rust in the floors, and whether the community has approved any works. That tells you whether you need a surveyor to look at the building first.

What the HOUSINGFAX report tells you

Check 03, «Aluminosis», combines the year of construction held by the Spanish Cadastre (Catastro) with what the registered building inspection says, where one exists, and gives the likelihood in words: very low, low, moderate, high or very high. Check 02, «Risks by year of construction», places high-alumina cement alongside the other problems typical of that period.

Every figure carries its source and date, in one report with 22 checks. See how it looks in the sample report, then start simply: check your home for free.

What no record can tell you

The year and the inspection show whether there are warning signs, but they do not identify the material. Knowing what a joist is made of takes the building's design documents or a professional who examines it and, if needed, takes samples. That is why the report does not replace a technical inspection of the building: it tells you what to look into and how urgently.

Short answers

Is high-alumina cement the same as aluminosis?

No. High-alumina cement is the material; aluminosis is the deterioration that concrete made with it can suffer over the years. A building can have high-alumina cement joists in good condition.

How do you know whether a building has high-alumina cement?

From the design documents or the joist manufacturer's paperwork, or from a professional survey that examines the joists and takes samples if needed. The year of construction and the building inspection point the way but do not confirm it.

Is high-alumina cement banned in Spain?

Not as a product: the RC-16 instruction regulates it under the designation CAC. For structural concrete, the Structural Code requires a special study in each case.

What should I do if the flat I like is in an older building?

Ask the community of owners for the latest building inspection and the minutes of any approved works, and check the likelihood the report gives. If it is moderate or higher, commission a professional survey before signing.

Official sources you can consult

The links let you review the primary source. Their inclusion does not widen their purpose or turn a piece of context into a diagnosis.