Investi̇gati̇on of the effect of fly ash addi̇ti̇on on mechani̇cal properti̇es in vacuum appli̇ed rei̇nforced fi̇eld concretes

Concrete is an important place among the materials that form the basis of developed societies. The cross-section thickness of the field concretes made of concrete and exposed to open air is less than the other reinforced concrete building elements and the surface areas are very wide. Therefore, they may show different reactions to the effects they are exposed to. These effects impair the durability of the concrete over time. The compactness of concrete must be increased in order to minimize the durability of concrete and to extend its service life. Therefore, different techniques can be applied to field concrete. During vacuum application, the capillary spaces are closed with the vibration that occurs while the water is withdrawn and a more filled concrete is obtained. In concrete applications, compressive strength is considered as the most important feature. Many of the other features change in direct proportion to the compressive strength. It is not always possible to say the same thing for durability. Therefore, it is possible to improve concrete durability by using mineral additives. In addition, the most expensive material in the concrete mixture and the material that pollutes the environment during its production is cement. In the world, cement factories are one of the leading factories that cause environmental pollution. Therefore, it is possible to improve the mechanical properties of the concrete as well as to obtain a more economical and environmentally friendly concrete by using different additives instead of cement. For this purpose, in this study, 15 * 80 * 80 cm reinforced concrete slabs of concrete class C25 were produced, vacuum was applied to the produced plates, after 28 and 90 days 10/10 cm, 15 * 15 * 40 cm and 4 * 4 * 7 cm core samples were taken. The results were compared by performing compressive strength, bending test, abrasion test and capillary water absorption test. In addition, the compressive strength test was carried out in two ways, with and without reinforcement. In reinforced concrete slabs produced, cement was replaced with fly ash at the rates of 0%, 5%, 10%, 15% and 20%. As a result of all experiments, it has been concluded that vacuumed concrete samples give better results compared to non-vacuumed samples. However, the 90-day experiment results gave better results due to the pozzolonic activity of the fly ash compared to the 28-day experiment results. In addition, reinforced core samples gave higher compressive strength than non-reinforced core samples.