Повышение защитной способности стальной арматуры в керамзитобетонах
Test subject – hydraulic activity of haydite and corrosion condition of steel reinforcement in expanded-clay concrete.
Purpose of work - a study of hydraulic activity of haydite and develop ways to improve the protective ability of expanded-clay concrete in relation to steel reinforcement
Methods of research - complex of modern standardized, as well as widely recognized by scientific community physicochemical, electrochemical and physical-mechanical methods of research of raw materials and samples obtained.
Results of the work - chemical methods of analysis revealed that aggregates of expanded clay have the ability to bind calcium oxide. The ability to enter into chemical interaction increases depending on the total content of SiО2 and AI2O3 and decreases with increasing of the filler size. This in turn reduces the pH of the liquid phase of concrete and can cause a corrosion of reinforcement.
The positive effect was achieved through the development of methods of mathematical modeling of hydrophobizating-plasticizing additive (GPA) and adding it into expanded-clay concrete mixture. This additive has reduced the normal density and timing of setting of cement paste, increased strength of concrete by 20-30% and reliably protected the steel reinforcement from corrosion.
Main technological characteristics. It was established that the minimum consumption of cement, not couse corrosion of reinforcement in expanded-clay concrete of>
Calculations indicated that when the cement consumption in expanded-clay concrete is 300 kg/m3 calculated thickness of the layer of cement paste between the grains of the filler should be not less than 3.26 microns.
The study of differential porosity of the concrete found that in lightweight concrete on porous and quartz sand is dominated by capillary radius of 1105 106 cm. At that the volume of smaller pores with radius 105 106 cm in lightweight concrete on porous sand 1,5 - 3 times more than in the heavy concrete.
Found that the introduction into cement system of hydrophobizating-plasticizing additive in an amount of 5% by weight of cement normal density of cement decreased by 17%. With the introduction of 7% of GPA reduction in normal density is 20%.
In combination with sodium nitrite complex modifier GPA shows synergistic effect, resulting in a plastification of concrete mix, increase strength and hydro-physical properties of concrete, and reliable protection of steel reinforcement from corrosion.
Application of the complex modifier in the technology of lightweight concrete improves durability of reinforced concrete structures and reduces their weight by over 30%, significantly increase the efficiency of vehicles for transport of reinforced concrete structures.
Degree of implementation. The composition of lubricant for the forms and hydrophobizating-plasticizing additive, the technology of their preparation and introduction into the concrete mixture are introduced at LLP Stroykombinat "(Uralsk), where the output of prestressed concrete sleepers from expanded-clay concrete was 50 м3.
Area of application. Building. Production of building materials.
Economic efficiency. Economic effect of the proposed technical solutions was 6446 tenge per 1 м3 of concrete.
Подписано к печати «19» октября 2010 г.
Формат 60х84/16. Печать офсетная. Бумага офсетная.
Объем 1,2 п.л.
________Тираж 100 экз. Заказ № 350______________
Типография АО «НЦ НТИ»
050026, г. Алматы, ул. Богенбай батыра, 221