Pole is a multiphase body of steel, cement, sand and gravel aggregate, consisting of pores and water, its physical, chemical and mechanical properties are mainly determined by the cement. In the production process of the pole, by the hydration of Portland cement to produce new compounds, calcium hydroxide, hydrated calcium silicate, hydrated calcium aluminate, hydrated iron, calcium sulphoaluminate hydrates etc., pH value of the alkaline concrete. Due to the long exposure in the open environment, and the environment by the action of wind and rain water (rain water, spring water, ground water, sea water, etc.) and a variety of external and internal erosion stress, multi-lateral rod appears, vertical and mesh cracks and reinforced internal erosion, surface smooth pulp barrels pole layer off, exposing the mortar and stones, while the rod will be "sweating, take the base." The above phenomena are aging diseases will significantly shorten the life of the pole, is to identify economically viable measures to slow the aging pole, but also begin to analyze the composition from the pole.

     Aging mechanisms poles
     Effects of carbonation on poles cracks and corrosion in the steel rod
     Carbonation is when hardened cement in the air condenses, the role of carbon dioxide with calcium hydroxide in the concrete surface with the air to form calcium carbonate shell. Carbonation generally does not reduce the strength of the pole, but lost the basic protection of the concrete effects of reinforcement, resulting in the passive film inside the reinforced concrete surface damage. With the constant intrusion of oxygen and moisture, it produces steel electrochemical corrosion, rust generated by the volume of steel corrosion after about 2 times the bar, so that the protective layer of concrete action by the swelling increases, and when the expansion force is greater than the resistance of concrete when tensile strength, concrete protective layer will crack along the ribs, making direct contact with the atmosphere steel, reinforced concrete cracks District carbonized steel corrosion is more serious than the district, carbonation and electrochemical corrosion sharply accelerated, resulting in the destruction of caving pole structure.
      Affect the impermeability of concrete, frost resistance, corrosion resistance durability of poles
      Impermeability even when the pore water seepage Chung internal pores formed by the pole into the pole body and the environment due to the role of frozen water erosion of media, concrete susceptible to freeze-thaw erosion and destruction of these channels in addition to vibration generated during the construction not dense and crack, but mainly from the evaporation of excess grout and leave pores, and when poor water retention properties of the slurry, moisture migration into place to form capillary pores, which have become permeable channels in concrete and water gap gravel and other aggregates under. How much water seepage channels, mainly related to the size of the water-cement ratio. Water-cement ratio hour impermeability high, low and vice versa impermeability. When the water-cement ratio greater than 0.6, the permeability coefficient surge significantly decreased impermeability.
      Frost resistance is mainly caused by freeze-thaw damage of concrete water freezes inside the capillary pores. When water freezes, the volume increase of about 9% when the material is cold water-filled capillary slot, the water in the first capillary surface of the neck part of the material is frozen, the ice plug formed in the pore water tight sealing up, if the temperature continues to drop, ice forming huge increases hydrostatic pressure in the pipe, can be subject to appropriate capillary wall tensile stress when the tensile stress exceeds the tensile strength of the concrete, the capillary wall cracking will occur locally. External manifestations of the rod to produce small cracks, the original smooth surface scarring or even a large area off, exposing the gravel aggregate. Freeze-thaw cycles, the more concrete material damage is more serious, this phenomenon is very obvious in the north of China.
     When the pole etch resistance to physical and chemical effects of environmental water, calcium hydroxide constituent structure of concrete, hydrated calcium aluminate, iron, calcium hydration, hydration sulphoaluminate etc. are gradually destroyed, reduced strength, called environmental water erosion. Wherein the calcium hydroxide can be dissolved in water to some extent (especially in soft water); acids and calcium hydroxide, hydrated aluminum, calcium and other alkaline substances, water and the environment, and a reaction of this salt to produce new compounds, or soluble in water, or soft power without cementing material, or can crystallize expansion, the formation of harmful stress and damage to the concrete structure, which affects the durability of concrete, the main erosion types are the following:
    ① dissolution of etching (soft water erosion). The strength of the dissolution of erosion and water quality in the hardness. When environmental water erosion and erosion pole, calcium hydroxide is dissolved continuously, especially the rod when there is a gap or dense enough, the action of water under pressure, into the water within the concrete, and the leaching of calcium hydroxide was dissolved out. This continuous process will enable hydrated calcium silicate and hydrated calcium aluminate further decomposed, resulting in decreased strength of the rod and destroyed.
   ② carbonated erosion. Setting water containing free carbonic acid (CO2) and the pole from a chemical reaction with calcium hydroxide, to form calcium carbonate, and calcium carbonate, and from the reaction of water-soluble calcium bicarbonate, the reaction will result in continuous rod strength decreases and destroyed. The reaction is as follows: Ca (OH) 2 + CO2 = CaCO3 + H2O
     (1) CaCO3 + CO2 + H2O = Ca (HCO3) 2
     (2) ③ general acid etching. Some industrial wastewater or groundwater hydrochloric acid and sulfuric acid and the free pole of the role of calcium hydroxide, to form the corresponding calcium salt, the following reaction: Ca (OH) 2 +2 HCI = CaCI2 +2 H2O
     (3) Ca (OH) 2 + H2SO4 = CaSO4 · 2H2O (gypsum)
     (4) wherein the water-soluble calcium chloride, gypsum crystals in the pores within the debris, the volume expansion of the concrete damage. The smaller the pH of the water environment, the erosion of the more serious. ④ sulphate erosion. Water, ground water and salt water marsh sulfates and other minerals in the water with poles in the role of calcium hydroxide to produce gypsum. When crystallized gypsum concrete pore volume expansion of the concrete damage; More seriously, gypsum and hydrated calcium aluminate in the concrete work, containing large amounts of water of hydration of the crystalline calcium aluminate sulfur, the volume is increased to about 2.5 times the original volume of hydrated calcium aluminate, able to play a huge role in the destruction of concrete. Sulphoaluminate hydration was needle-like crystals, often called "cement bacillus", that is, we often say "take the base." 3CaO · Al2O3 · 6H2O +3 (CaSO3 · 2H2O) +19 H2O = 3CaO · Al2O3 · 3CaSO4 · 31H2O
     (5) ⑤ magnesium erosion. Seawater, magnesium and other minerals rod ground water and calcium hydroxide in effect, the product is soluble in water such as calcium chloride, magnesium cement softly without force, gypsum is produced as described above and then etching sulfate .
     Prevention and cure
     By analyzing the carbonation poles by air and water environment, the failure mechanism penetration, freezing and thawing, erosion, etc., we can find comprehensive prevention poles aging, measures to improve the life of the cement pole, which is divided into the following three phases:
     According to the design phase transmission line geology, hydrology, climate, industry structure, environmental pollution and other information, select the appropriate cement manufacturing reinforced concrete pole varieties. Manufacture of cement poles are the following:
     (1) 425 ordinary portland cement: basic varieties, the most extensive range of applications.
     (2) Slag Portland Cement: Anti-stripping sulfates and anti-erosion of ability. Water and magnesium antacid poor, poor permeability and frost resistance, carbonation fast, easily corroded steel.
   (3) pozzolana cement: Bleeding, good impermeability, frost resistance but poor.
   (4) fly ash cement: minimum shrinkage, cracking the best anti-erosion resistance.
   (5) sulphate resisting cement silicate: Anti sulfate and freeze-thaw resistance. Coastal saline areas, Zaozhuang, Xinwen and other sulfide ore region, Zibo and other industrial wastewater into the region, hydrochloric acid, sulfuric acid, magnesium sulfate and severe erosion, should adopt the fly ash or sulphate resisting portland cement silicate poles or low silicon content aluminum tris (8%) of ordinary portland cement poles. Taian Lu, Luxi freezing frequently (50 times greater than the annual cycle), the coldest months the average temperature is below -8 ℃, poles aging diseases in the form of freeze-thaw damage based, should adopt sulfate, silicon acid cement pole. Less ice flood, lake, etc., should be adopted pozzolana cement poles.
    Manufacturer's control process
   (1) manufacturing processes meet the strict control of water gray, poles pulp barrels Seiko surface pressure can increase the density of poles to reduce infiltration and reduce environmental water erosion damage. Thick concrete protective layer, so that the depth is greater than the carbonation of concrete, reinforced protection so that concrete carbonation depth greater than that of reinforced protection can rust crack. 1.5% -2% of steel fibers, glass fibers, plastic fibers and other materials, centrifugal casting made ​​of high-strength fiber reinforced concrete poles, can effectively inhibit the production of micro-cracks.
   (2) Add the appropriate admixture admixture of two inorganic and organic compounds. Most of the organic compound is a surfactant, such as reducing agent (calcium lignosulfonate) can reduce the amount of cement and water, reduce water-cement ratio and improve the strength and durability of concrete; entraining agent (rosin hot polymer) can improve impermeability, frost resistance and crack resistance of concrete. Most inorganic compounds are electrolyte salts, such as rust inhibitor (NaNO2), can effectively extend the life of reinforced concrete.
     Construction, operation and maintenance repair
    "Overhead transmission line construction and acceptance norms" Although only requires plugging the upper end of the pole, but the construction of the lower end of the block should also be more effective in the prevention of environmental water into the dip. If the substation site and route via ground geological bad, can be "soil cement" law, namely mixing cement backfill cement pole, the pole or after a good stand, surrounded by mud and water poured into the rod. For surface water, mud bucket rod has produced spalling can be set in concrete surface protective layer, such as Lek table waterproof layer, an impermeable layer of cement shotcrete and nutrients waterproof layer. As the water surface of the glass rod in the priming solution, and the resultant silica gel rather [Si (OH) 4] can be uniformly adsorbed on the surface of the concrete and inside it about 1mm, in constant dehydration and condensation process, the formation of numerous small pores having connecting phase, reducing permeability of concrete approximately 35% resistant to most inorganic acids erosion, thus extending the life of the pole. For cracks on the rod, when the crack wider when (2mm above), should be carbonized after chiseling concrete, epoxy mortar, polyester mortar, polymer cement mortar and high-grade cement mortar to repair. When the crack is small (0.5mm), can be painted epoxy cement thickness not exceeding 0.1mm, surface treatment before the first brushing, brushing with a wire brush impurities dry after washing with water, the ingredients evenly and then the stirred brushing the pole surface, this method can delay the development of aging diseases poles, valid for up to 5 years.

       Shandong Sheng Machinery Co., Ltd. has been dedicated sub-cement products machinery research and development, production and sales, with advanced equipment, superb technology and two years of professional experience, the company has always been at the forefront of research and development center block making machine market development , watching the advanced technology at home and abroad, to develop products for the investment needs of different users, there are block making machine, hydraulic tile machine, cement pipe machine, blender, hanging roller machine, wire rod machine equipment. Currently has 19 branch offices and six foreign countries (Nigeria, Tanzania, Algeria, Kenya, Mozambique, Ethiopia) and exported to more than 100 countries and regions.