تخمين نفوذپذيري محيط متخلخل بتن براي مشتقات نفتي با استفاده از روش "محفظه‌ي سيلندري"

Assessing the permeability of the oil and its components into porous concrete using new Cylindrical chamber" method

دوام و پايايي بتن در برابر نفوذ مايعات همواره از بتن انتظار مي‌رود. براي هر گونه ارزيابي دوام، بايد نفوذپذيري و مقاومت بتن ارزيابي شود. بر اين اساس در اين نوشتار، اندازه‌گيري نفوذپذيري با استفاده از روش "محفظه‌ي سيلندري" صورت گرفته است. اين روش كه قابليت انجام در محل را دارد، قبلاً براي تعيين نفوذ در برابر آب مورد استفاده قرار گرفته است. در نوشتار حاضر، كاربرد روش مذكور براي نخستين بار براي مشتقات نفتي (نفت سفيد و بنزين) به‌كار رفته و با آب مقايسه شده است. ميزان نفوذپذيري در برابر مايعات مذكور در بتن، با مقاومت‌هاي 30،20، 40، و 50 مگاپاسكال اندازه‌گيري شده است. نتايج آزمايش‌ها نشان مي‌دهد كه با افزايش مقاومت فشاري، مقاومت سطحي و مقاومت در برابر نفوذ سيال در شرايط آزمايشگاهي خشك افزايش مي‌يابد. همچنين تفاوت معناداري بين گرانروي سيالات و ميزان نفوذپذيري آن در بتن مشاهده مي‌شود.

In the concrete storage tanks used in oil industry, displacements, cracking, durability, and permeability are the factors to which must be paid enough attention. Furthermore, in order to evaluate the durability of any concrete structure, its strength and liquid permeability as the most influential factors should be assessed. Oil and its components can harm concrete in two ways. One way is the corrosion of the reinforcement in the reinforced concrete structure, and the other is the detrimental effect of the oil and its components on the constituent materials of the concrete by dissolving them and producing new products with much less strength and durability. Therefore, in this paper, the results of the use of a newly developed "cylindrical chamber" method, which was used to assess the permeation of oil and gasoline into concrete with different strengths, are presented. The portable "cylindrical chamber" apparatus consists of a metallic base ring, a cylindrical chamber, a pressurizing screw, and a dial gauge. In order to measure the liquid permeability of a medium, the base ring is attached to the surface of the medium using high strength epoxy glue. After setting and hardening of the glue of the base ring, which is usually completed by about 24 hours, the cylindrical chamber is attached to the base ring simply by twisting the chamber and fixing it. The lower section of the cylindrical chamber is equipped with a rubber ring which prevents the leakage of the liquid. Having fixed the cylindrical chamber on top of the base ring, the chamber is filled with the intended liquid. For pressurizing the liquid, the screw is turned clockwise until the required pressure is shown on the dial gauge. For the present research, concrete cubes with different strengths were cast and cured for 28 days, using water tank for curing. The strength of the concrete mixes used ranged from 20 to 50 MPa. The results show that as the concrete strength increases, the permeability of the liquids used tends to decrease. It was also seen that any increase in the unit weight of the liquids used tends to reduce the amount of the permeated liquid in the concrete.