Abstract. Self-compacting concrete is a very perspective building material. It provides great benefits during the construction of heavily reinforced buildings. SCC has outstanding properties such as high flowability, dense structure and high strength due to specific quality of aggregates, fillers, their proportion in mix, use of polycarboxylate-based superplasticizers. Main disadvantages of SCC are high price and the difficulty of obtaining a proper mix. Use of fillers, such as fly ash type F, is a way to make SCC cheaper by replacing part of cement. Fly ash also provides some technological and operating advantages. In this paper the influence of high volume (60% from cement) fly ash type F on the properties of concrete mixture and hardened concrete is investigated. The result of the work shows the possibility of reduction the cost of SCC using ordinary fillers and high amount of fly ash. The investigated SCC has low speed of hardening (7-day compressive strength at the range of 41.8 MPa) and high volume of entrained air content (3.5%).
The problem of waste reuse from building industry is acute around the civilized world. The construction of infrastructure in large cities increases the amount of building waste. This study presents the possibility of using concrete waste of residential buildings included in the renovation program of the Moscow. The use of recycled aggregates obtained from demolished concrete allows saving the content of natural aggregates in concrete and significantly reducing the amount of waste that pollutes the environment. Their use is possible in structures with the proper concrete mix content with maintenance of the same properties. Recycled concrete aggregates differ from natural aggregates as the former aggregate contain adhered mortar. The content of the adhered mortar in coarse recycled concrete aggregate was determined on fraction of 5-10 mm. In this study, limestone aggregate was used as initial in structure of recycled concrete aggregate. The quantitative content of crushed concrete components was carried out using quantitative analysis. The main characteristics including specific gravity and water absorption of recycled aggregate were determined. The specific gravity and density of aggregate were 2.59 g/cm3 and 1.9 g/cm3, respectively. The water absorption and mortar content were 3.8% and 39.9%, respectively.
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