جستجوی مقالات مرتبط با کلیدواژه « محیط های کلریدی » در نشریات گروه « عمران »

Self-compacting concrete (SCC) is known for its outstanding characteristics such as superior mechanical and durability properties. Corrosion of rebar due to penetration of chloride ions in the reinforced concrete elements is of particular importance. Therefore, this issue in the SCC must be investigated. Pozzolanic materials could be used in the SCC to increase the resistance of concrete against chlorine ion penetration. In this research, effects of pozzolanic materials including micro silica, nano silica, fly ash, rice husk ash, as well as limestone powder on the mechanical and durability characteristics of self-compacting concrete placed in chloride environment have been studied. The results show that nano-silica increases the mechanical and durability characteristics of self-compacting concrete. Moreover, the SCC containing combination of nano-silica and pozzolanic materials has better properties than the one containing nano-silica.

Chloride ions cause the most common corrosion, so chloride ions can enter the concrete through contaminated aggregates and additive materials or infiltration from external sources, such as seawater. If the concrete is exposed to the aforementioned ions, there will be severe loss of durability and expansion of corrosion. In this case, there will be a tangible effect on the development process of resistance reducing the concrete's strength. Therefore, the extant study was conducted to compare the effect of fly ash and micro silica on the development, compressive strength, and electrical resistance of concretes exposed to chlorinated waters. The plans of this study included two types of ordinary concretes and concretes containing pozzolanic material. Concrete mixing plans in chloride medium were divided into 11 groups, which included 8 plans with substitution of micro silica and fly ash powders with different percentages in exchange for cement. The first group included no additive material as a cement substitute and included one plan as the base plan. Accordingly, 81 plans that each consisted of 4 samples were constructed and examined to test compressive strength in 7, 14, 28, and 42-days ages (N=324 plans). According to the results of laboratory samples in chloride medium, there was an increase in the development process of compressive strength, and electrical resistance of concrete while using concrete with standard aggregates reinforced with micro silica and fly ash by selecting the optimal mixing plan and lower cost. The above mentioned case was cost-effective for project implementation.