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Declining pH levels in aging concrete structures can lead to continued, costly maintenance over the life of the structure.  Proper sealing and waterproofing of steel reinforced structures is an important step in prolonging its useful life.

You check soil conditions to make sure pH levels are properly suited to your landscape plants.  You check the pH levels in your swimming pool to make sure the water stays sparkling clean.   Did you know that the pH levels in your steel reinforced structures are just as important?
 
As concrete structures age, the pH levels in the concrete decline and the acidity drops.  What follows can be continued, costly maintenance over the life of the structure. 

When concrete is first poured it has a high pH level of between 11 and 13.  This is due to the presence of calcium hydroxide.  Under ideal circumstances a thin coating of iron-oxide forms on the steel reinforcement bars protecting them from corrosion.  Over time, however, the intrusion of salts, leaching, or carbonation can reduce the pH levels in the concrete surrounding the reinforcement.  If the pH value drops to a level of 8 or 9, the steel reinforcement bars, or rebar, can become corroded, beginning a cycle that could lead to further concerns and the acceleration of structural decay.
 
Carbonation is a chemical reaction that occurs when carbon dioxide in the air reacts with the calcium hydroxide and hydrated calcium silicate in the concrete.   From the time the structure is made, carbon dioxide starts to carbonate the cement in concrete, lowering the pH levels and destroying the protective iron-oxide film around the rebar.  The rate continues to accelerate as pH values decrease further, increasing the corrosion rate of the bare steel. 
  
The cycle of decay begins when the unprotected steel bar starts to rust.  Slight cracking of the concrete occurs when the rust on the rebar expands at its surface where it touches the concrete.  As the corrosion builds up over time it can cause more extensive cracking.  Without proper waterproofing, this exposure to the elements only accelerates the process and the likelihood of further damage to the structure.  In severe cases, a condition called spalling can occur and the concrete breaks away from the bar completely. 
 
Left unattended, the pattern of deterioration often results in ongoing and costly repairs throughout the life of the structure. EDS partners with structural engineers for structural repairs and, when needed, core sample testing companies to determine ph, carbonation and chloride levels of your concrete. However, regular power washing and sealing can help prevent the destructive process in the first place. EDS can inspect your property for any signs that may lead to something more serious and offer economical preventive maintenance services to protect your structure from damage, expensive repairs and loss of parking revenue.