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Protecting Reinforcement Bars in Concrete

Posted by Pedram Mojarrad on

Reinforcement bars are actually very safe, when completely covered by concrete. The pH of concrete is perfect for the reinforcement steel, so, as long as this pH has not dropped to lower numbers, or the concrete has not cracked or ... the steel bars will stay safe and sound in the concrete. But as you can tell, this may not last very long, specially in very corrosive areas, or when a concrete has cracked (due to plastic or drying shrinkage or structural reasons). Chloride induced corrosion is a big deal in coastal areas (like all capital cities in Australia).    To cut the long...

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Cracks on concrete balconies- Where did they come from?

Posted by Pedram Mojarrad on

Late last year, GESS were engaged in forensic studies and then repair of balconies (8 of them) in a residential buildings in Sydney- Northern Beaches.There types of cracks were quite obvious: 1- Side cracks; which we figured out to be due to chloride attack, and2- Flexural cracks (soffit of slab); which are structural cracks.     Reinforcement corrosion has become a serious, widespread problem worldwide, with costly repair methods. The steel corrosion in reinforced concrete reduces its durability and can even result in failure of the structure. Corrosion is a phenomenon which results in the deterioration or destruction of a material when...

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Acid Resistant Solution

Posted by Pedram Mojarrad on

How can we protect concrete against acids, specifically those strong ones?

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Why did your epoxy coatings bubble?

Posted by Pedram Mojarrad on

Have you ever seen bubbles in epoxy floors? do you know why those pop up at all? Bubbles don't look good in what we expect of resin flooring systems (seamless, consistent looking coatings).     What are they? These pinholes in the coating appear as small blisters or bubbles. After the blisters pop, they leave round bowl-shaped bubbles that can be seen through the transparent film.   Causes: 1- Outgassing: Air can escape from the porous substrate and becomes trapped in the coating. So substrate preparation is really important here.  2- Temperature/Humidity: If too hot or humid, it can result in rapid drying...

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How to clean Concrete from rust marks?

Posted by Pedram Mojarrad on

Recently, on one of our job sites, we were asked to clean the concrete slab (underside) because there were rust marks everywhere and they were not able to clean it with high pressure water.   Rust marks were everywhere, almost on 150 sqm, area. And presumably, they came from reinforcement bars or rod ties. Either way, poor concrete placement was the main cause, again.   We started with trying different things: 1- Acid washing: Hydrochloric acid washing could be a fast way to do this, but it didn't work. We even increased the dosage of acid in the solution, and sprayed...

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