Durability is the ability to last a long time without signifcant deteriorationFactors Related to Concrete Durability1. concrete cracks2. High Humidity and Rain3. Freezing and Thawing. Carbonation!. "ul#ate $ttack%. $cids attack &. "eawater '()osure*. Chloride and "teel Corrosion+. $lkali,"ilica Reaction -$"R.1/.$brasionconcrete cracksConcrete, like most materials, will shrink slightly when it dries out. Common shrinkage is about 1/16th of an inch in a 10-foot length of concrete. The reason contractors lace !oints in concrete a"ements and #oors is to allow the concrete to crack in a neat, straight line at the !oint, where concrete cracks due to shrinkage are e$ected to occur. Control or construction !oints are also laced in concrete walls and other structuresHigh Humidity and Rain0high humidity only don&t a'ect on concrete durability butwith carbon dio$ide or another acid content will induce concrete erosion or/and ()T corrosion Freezing and Thawing0The most otentially destructi"e weathering factor is free*ing and thawing while the concrete is wet, articularly in the resence of deicing chemicals. +eterioration is caused by the free*ing of water and subse,uent e$ansion in the aste, the aggregate articles, or both.Carbonation by Contact with 2ater-aters with a . greater than 6./ may be aggressi"e if they contain bicarbonates, also contains free carbon dio$ide. -ater with this aggressi"e carbon dio$ide acts by acid reaction and can attack concrete."ul#ate $ttack0.igh amounts of sulfates in soil or water can attack and destroy a concrete that is not roerly designed. 0ewage and sea water both contain dangerous amounts of sulfate will enetrate hardened concrete and attack it by con"erting calcium aluminates C12 and sulhoaluminates into calcium sulhoaluminates. The e'ect on the concrete is e$ansion which tears the concrete aart.3 0ulfate attack is more se"ere at locations where the concrete is e$osed to wetting and drying cycles, than continuously wet cycles.3 "ul)hates in the en3ironment4 sulhates can arise from two main sources in the en"ironment 5 seawater and soil and groundwater6icroscoic "iew of sulhate attack3 $cids attack concrete by dissol"ing both hydrated and unhydrated cement comounds as well as calcareous aggregate. 7n most cases, the chemical reaction forms water-soluble calcium comounds, which are then leached away. 0iliceous aggregates are resistant to most acids and other chemicals and are sometimes secifed to imro"e the chemical resistance of concrete3 Concrete deterioration increases as the . of the acid decreases from 6./. 7n fact, no hydraulic cement concrete, regardless of its comosition, will hold u for long if e$osed to a solution with a . of 1 or lower. To rotect concrete from such se"erely acidic en"ironments, surface treatments are often used. Fig. 2: Concrete surfaces with diferent depths of erosionThere are essentially three ways to im)ro3e concrete4s resistance to acids1. choosing the right concrete comosition to make it as imermeable as ossible8. isolating it from the en"ironment by using a suitable coating1. modifying the en"ironment to make it less aggressi"e to the concrete.3 "eawater '()osure4 Concrete has been used in seawater e$osures for decades with e$cellent erformance. .owe"er, secial care in mi$ design and material selection is necessary for these se"ere en"ironments. 2 structure e$osed to seawater is most "ulnerable in the tidal or slash *one where there are reeated cycles of wetting and drying. 0ulfates and chlorides in seawater re,uire the use of low ermeability concrete to minimi*e steel corrosion and sulfate attack. 2 cement resistant to sulfate e$osure is helful. 9roer concrete co"er o"er reinforcing steel must be ade,uate, and the water-cementitious ratio should be lower "alueChloride Resistance and "teel Corrosion0Chlorides resent in lain concrete :that which does not contain reinforcing steel; is generally not a durability concern. 7n reinforced, the aste rotects embedded steel from corrosion through its highly alkaline nature. The high . en"ironment in concrete :usually :greater than 18./; causes a assi"e rotecti"e o$ide flm to form on steel. .owe"er, the resence of chloride ions from deicers or seawater can destroy or enetrate the flm.