Nanotechnologies in Construction: A Scientific Internet-Journal

65-70

Authors: Kiyamov I.K., Vachitova R.I., Saracheva D.A., Sidina D.V., Sabitov L.S.

To improve physical and mechanical properties of pavements new materials with nanomodified additives are being actively developed. The authors are investigating the properties of road petroleum bitumen with nanomaterial Taunit. At the initial stage, oil bitumen was heated to 100о C. Then carbon nanomaterial «Taunit» was added. After that, the mixture was stirred in an ultrasonic homogenizer until even distribution of the carbon nanomaterial in the total volume. The process of cooling of the final structure was carried out until the end of the crystallization process. Then, the specimens are exposed to tension and strength tests with a constant rate of deformation or loading until the moment of rupture on the testing machines. Mixing with other components of asphalt concrete in the standard mode follows the nanomodification of the bituminous mixture. Under increased temperatures the bitumen mixture keeps properties of an effective binder. It was revealed that the modified carbon bitumen has good thermal properties, namely, it has a higher softening temperature (Δt is in the range from 6 to 10ºС). The indicator, which indirectly characterizes the degree of hardness of bitumen solutions, is within the limits of GOST standards, decreases by 15–20%.

77-83

Authors: Massalimov I.A., Massalimov B.I., Akhmetshin B.S., Urakaev F.K., Burkitbaev M.M.

The data of studies on the effectiveness of impregnating Aquastat waste generated as a result of the development of limestone-shell rock deposits are presented. As a result of sand impregnation, the water absorption coefficient as a result underwent a significant decrease from 7 to 17 times, while the water absorption coefficient decreases from 32.5% for the initial to 1.9% impregnated. Even treatment with low concentrated (ρ = 1.17 g / cm3) calcium polysulfide solution made the water absorption coefficient to decrease to a value of 4.5%. As a result of impregnation of crushed stone from limestone-limestone with a solution of calcium polysulfide, the water absorption coefficient decreases from 25.0% for untreated to 5.2% for treated, and the decrease in the coefficient of water absorption is greater for concentrated solutions. It was found that a solution density of 1.24 g/cm3 is sufficient to reduce the water absorption coefficient to a value of 5.2%, the same as for a density value of 1.35 g/cm3. Comparison of the results of impregnation with «Aquastat» solution and sulfur melt showed that as a result of treatment with sulfur melt, the water absorption coefficient decreases by 13.3 and strength increases by 2 times, and as a result of impregnation with «Aquastat» solution decreases by 4.62%, strength increases by 1.35 times. Despite the high efficiency of sulfur melt processing, such treatment has drawbacks associated with the use of autoclave technology and high temperatures. The results of the modification of sand and crushed stone from shell rock by impregnating it with the «Aquastat» solution, a significant decrease in the water absorption parameter, an increase in compressive strength, revealed the possibility of using impregnated crushed stone as the layer material lying at the base of the road structures of local roads in the form of crushed stone and sand instead of the more expensive imported crushed stone.

94-99

Authors: Mazitova A.K., Vikhareva I.N., Maskova A.R., Gareeva N.B., Shaikhullin I.R.

Modern operating conditions of polyvinyl chloride (PVC) materials impose increased requirements for the additives used. Intensification of processing and expansion of PVC application areas, as well as providing a wide variety of its performance characteristics, are associated to a large extent with the successful solution of the problem of creating effective plasticizers. Therefore, when developing formulations of PVC plasticates, it is important to obtain and select plasticizers that meet modern high requirements for operation and environmental safety. One of the modern approaches to creating materials that can be destroyed in natural conditions is based on the use of additives that increase the ability of polymer materials to biodegrade. This paper presents the results of developing a PVC composition with increased biodegradation. For this purpose, a mixture of plasticizers was used: dibutoxyethyl phthalate (DBOEP) with a degree of ethoxylation of 1.5 and dibutoxyethyl adipate (DBOEA) with a degree of ethoxylation of 1.5. The results of testing samples of obtained PVC compositions for biodegradation are presented. It is shown that partial replacement of a phthalate plasticizer with a non-toxic biodegradable dibutoxyethyl adipate makes it possible to obtain PVC compositions with increased biodegradation, while maintaining excellent performance properties.

108-115

Authors: Sikora P.

This study presents an investigation of the effects of high temperature on the thermal and microstructural properties of cement mortars modified with nanosilica. In the first stage of the research, the effects of nanosilica (NS) and silica fume (SF) on the hydration and compressive strength of cementitious composites were compared. In the second stage, four different types of cement mortars, containing an optimal dosage of NS, were produced. Two of them contained a normal weight aggregate (quartz or limestone), whilst two contained a heavy weight aggregate (barite or magnetite). Specimens without NS were produced for control purposes. The specimens were exposed to 300, 450, 600 and 800°C, with their post-heating properties – including thermal conductivity, specific heat, solvent absorption and cracking behavior – analyzed. The results show that NS exhibits significantly higher reactivity with cement than SF. NS accelerates the cement hydration process and contributes more significantly to the 28 and 365 day compressive strength of mortar, as compared to SF. The incorporation of NS in a composite substantially decreases the amount of CH in the mixture and leads to the production of additional C–S–H gel phase, which improves microstructure. The study also shows that NS contributes to a decrement in the thermal conductivity and density of mortar, both prior to and after heating. The incorporation of NS has a beneficial effect on decreasing the deterioration rate of mortars after heating, by decreasing absorption rate and the amount of cracks in in them.