The total salinity of the water content and caustic alkali, g / l of chemical action of sea water is mainly due to the presence of magnesium sulphate. In concrete, the reaction is Ca (OH) 2 + MO4> M (OH) 2 + Ca $ O4 Magnesium hydroxide is characterized by a lower solubility than Ca (OH) 2, but is formed as a dispersed mass, which leads to lower strength concrete. The greater the concentration of magnesium ions in water, the more dangerous water. Calcium sulfate reacts with calcium gidroalyuminatom: 6H2O + SAR 3SOA12O3 $ 04 + 25N20 3SOAi203 3Sa $ 023 1 H2O. The resulting complex salt (gidrosulfoalyuminat calcium) has a volume several times greater than the amount of starting material. As a result, expansion and destruction of the concrete. Another strong factor in corrosion is carbon dioxide, which may contain salt water in the presence of organic compounds that emit carbon dioxide during decomposition. This water dissolves the calcium carbonate.

The latter is formed in the cement stone of Ca (OH) 2 under the influence of the same carbon dioxide: Ca (OH) 2 + C02> CCO + H2O. In the presence of carbon dioxide goes into CCO soluble calcium bicarbonate, washed out of the concrete: CCO + C02 + H20 – Ca (HCO) 2. destruction of concrete in sea water caused partly the bacteria, the most active role played by those that oxidize sulfur to sulfuric acid. Seawater acts most strongly on the surface concrete directly above the top water level. At evaporation of water from the concrete in its pores is the solid residue formed from the dissolved salts in seawater. The constant flow of water into the concrete and its subsequent evaporation from open surfaces leads to the accumulation and growth of salt crystals in the pores of the concrete, which is accompanied by expansion and cracking of the latter.