توصيفگر ها :
بتن قليافعال سربارهاي , سنگدانه بازيافتي آسفالت , تاگوچي , آب دريا , يادگيري ماشين
چكيده انگليسي :
Concrete is one of the most widely used materials in civil engineering projects. Ordinary concrete is typically made using Portland cement. However, the production process of Portland cement is associated with the emission of a significant amount of carbon dioxide, leading to substantial environmental damage. One approach to mitigate these environmental impacts is to replace Portland cement binders with alkali-activated slag, which can be utilized in many civil engineering projects. Additionally, in recent years, the use of recycled materials in concrete has gained considerable attention. Recycled asphalt aggregate, obtained from the demolition of old asphalt pavements, is one such material. Moreover, given the widespread availability of seawater and the increasing scarcity of freshwater as a natural resource in recent years, the potential use of seawater in concrete has become increasingly significant and should not be overlooked. The use of seawater in concrete production is particularly advantageous in arid regions such as the Middle East, where there is heavy reliance on costly desalination processes to produce freshwater, or in coastal areas facing freshwater scarcity but have easy and economical access to seawater.
The present study involves testing alkali-activated concrete samples, which were prepared using slag as a cementitious material, sodium metasilicate as an alkali activator, as well as recycled asphalt aggregate, seawater from the Persian Gulf, and ordinary (potable) water. To examine the parameters influencing the mechanical properties of concrete with the aforementioned components, recycled asphalt aggregate replacement levels of 25%, 50%, 75%, and 100%, water-to-binder ratios of 0.49, 0.50, 0.51, and 0.52, sodium metasilicate-to-slag ratios of 0.16, 0.18, 0.20, and 0.22, and binder contents of 300, 350, 400, and 450 kg/m³ were considered, resulting in 256 mix designs. To minimize the number of experiments and achieve an optimal mix design with the highest strength while accessing the results of other designs, 16 mix designs were selected using the Taguchi experimental design method. These mixes were subjected to compressive, flexural, and tensile strength tests. The analysis of the results revealed that the compressive strength of concrete made with seawater decreased by 5% to 35% at 7 days compared to the corresponding mix made with ordinary water, depending on the amount of water used in the mix and the replacement level of recycled asphalt aggregate. This strength reduction decreased at 28 and 90 days, ultimately leading to a decrease in compressive strength of 5% to 25% compared to the corresponding mix made with ordinary water. The results indicate that by optimizing the mix components, a composition suitable for civil engineering and construction projects, particularly in areas facing freshwater and natural aggregate shortages, can be achieved.
