Defects in Concrete and Plastered Surfaces

Was the cement used within specs and within the "use before" date?

Dear friend

maybe its one of these reasons:1-cement of a bad quality(check cement test reports)2-water isn't valid (ask for testing water sample)3-conduits and ducts which were embedded before concreting or plastering there was no enough concrete cover over them.3-sand or aggregates which was used maybe having some types of undesired salts.

Hello,

It sounds like you've not finished your homework yet, so I won't tell you the answer. But, the way to correct your problem is a mild muriatic acid wash (about 5%), followed by a good sealer.

Lord, what fools these mortals be! - A Midsummer-Night's Dream

Oh oh it due the presence of .................. in the plaster mix and if certain aspects exist it will always occur or seasonally at least.

Sharpen ur point>

Hi chennaicivil,

I always experienced that in newly plastered surface and my mason/builder just applied concrete neutralizer, wash down with water to rinse, then apply of concrete sealer/primer. please be informed that the very important thing to consider before applying paint is surface preparation followed by material quality and the workmanship. if these three component done accordingly it will gives you the best finished product. of course if it is exterior weather condition must be take into account.

All of the above are based on my actual experienced.

Kind regards

Roman

Hello all,

To the above mentioned,(white patches). It sounds like efflorences! Usually caused when the sand/aggregates and or cement are contaminated with either ground salts or gypsum. The moisture in the atmosphere draws it to the surface until it is completely gone.

Usually left alone it will eventually clear up. Sealing the surface may work depending on where the problem starts. If the plaster is fixed to concrete and the problem starts in the concrete sealing the plaster could just cause the plaster to flake off.

Regards,

Tony.

The moisture in the atmosphere draws it to the surface until it is completely gone.

Often when improper vapor barriers are used the problem can reoccur seasonally for many years.

www.rudimentsofwisdom.com/pages/cement.htm