Sülfatın beton ve betonarme elemanlara olumsuz etkisi

Abstract

Keywords

• Sülfat etkisi, beton basınç değeri, betondaki bozulma, dayanıklılık

The negative effect of sulfate to the concrete and reinforced concrete elements

Abstract

One of the reasons deteriorations constitute at the concrete and reinforced concrete structures in the time is the effect of sulfate.Naturally occuring sulfates in soils and groundwater, after a series of chemical processes, may lead to durability problems causins expansion and disintegration of the hardened concrete. Concrete that expose to sulfate ions at high-density may destroy completely. Effect of fly ashes (FA) and blast furnace slag (BFS) on properties of superplasticizer (SP) added concrete was investigated against to sufate effect. FA and BFS were added to Portland cement (PÇ 42,5) 20 % by weight of the cement. FA and BFS replacement concretes were compared with each other as well as with Portland cement concrete. 15 cm cube specimens were prepared with produced concrete and cured at 7, 28, 90 and 150 days For this purpose, high density sulfate of soils were examined by comparing the ratio of TS 12457-4 Standards. In this study, pozzolanic additions were added to changing in ratio 20 % by weight of the (PÇ. 42.5) portland cement. The 0.56 water/cement ratio and 300kg/m3 cement dozage are selected as reference. A control concrete sample is also produced having the same dozage. The performance of mineral additives concrete was obtained both in the sulphate and water cures. In this context, three series of concrete samples was produced; in two concrete samples series the certain ratio of fly ash and granulated blast furnace slag was used as additives, and one series of sample was used without additives. In order to see the effect strength and durability of concrete at high-rate sulfate, concrete samples were rested in a solution of Na2SO4(150 g / l) in accordance with ASTM C 1012. One group of specimens was kept continuously in sodium sulphate solution with concentration of 150 g/l for 5 months.. The other group samples were rested in water and compressive strengths are presented as a comparatively. At the end of each curing period, a total of 3 specimens were tested for each concrete property. Surface hardness and compressive strength of Concrete samples exposed to Sulphate effect were measured regularly. At the same time, the surface distortions and changes of weight of the samples were observed periodically. As a result, sulfate is determined to decrease upon the strength and durability of concrete structures. Moreover, The results showed that use of %20 FA(Fly Ash) as replacement of portland cement increased the strength properties of concrete samples. Economical benefit can be achieved by using pozzolanic additions in the concrete mixture. As a conclusion use of such additions, waste materials, provide both durable and economic concrete structures and ecologic balance for.

Keywords

• Sulphate effect, concrete compressive strength, deterioration of concrete, durability