جستجوی مقالات مرتبط با کلیدواژه "یتن خود ترمیمی" در نشریات گروه "عمران"

Concrete is the most widely made construction material in the structural engineering world. Advantages such as high compressive strength, availability of raw materials, and low preparation cost make concrete one of the most important used construction materials. Under harsh environmental conditions, aggressive agents such as sulfates and chlorides penetrate the concrete through these cracks to damage the concrete. While concrete cracks are not only expensive to repair, they are often hard to detect as well. It is now identified that the strength of concrete alone is not sufficient, the degree of harshness of the environmental condition to which concrete is exposed over its entire life is very important. Self-healing concrete is a type of concrete that has the ability to repair itself without the need for an external agent during cracking. Concrete containing microorganisms has self-healing properties. The self-healing agent contains a specific concentration of bacteria with a nutrient in the concrete that produces calcium carbonate while the water and environmental conditions are suitable for the concrete. In this research, four different specimens of concrete have been made. Concrete containing microorganisms is made in two different concentrations of bacterium bacillus pasteurization (107,109 cells/ml) and calcium lactate nutrients and is compared with concrete containing silica fume, concrete containing latex and control concrete. In all four specimens, the same mix design was used with a water/cement ratio of 0.48 and containing silica fume, latex polymer, and calcium lactate, which replaced cement in different percentages. Specimens were subjected to compressive, flexural, and tensile strength tests at 7 and 28 days of operation, and the results were compared. The results showed that the best performance among all specimens for concrete containing silica fume and self-repair agent (bacteria and brain material) increased compressive strength and reduced tensile and flexural strengths compared to the controlled specimens. The use of a self-healing agent in concrete increases the compressive strength of concrete, but this increase is not as great as the increase in silica fume. Bacteria with a higher concentration have a negative effect on the compressive strength of concrete so that more use of bacteria in concrete increases the compressive strength to such an extent that it even reduces the compressive strength compared to the concrete strength of the control specimens. The self-healing agent reduces the flexural and tensile strength of concrete, as opposed to silica fume but they are better than latex and produce better results.