Exposure to elevated temperatures has detrimental effects on the properties of concretes based on the Portland cement, leading to irreversible changes, up to total failure. One of solutions to improve resistance of structures after exposure to high temperatures may be the use of cement-based materials modified at the nanoscale.
The modified concrete mixes design and cement concrete with the given operational parameters was developed. During the experiment, cement concrete was obtained from concrete mixtures of various compositions with modifying additives of a new generation containing a superplasticizer based on polycarboxylates and an air-absorbent additive. Superplasticizer was injected into a concrete mix with water in a quantity of 0,6; 0,8 and 1,0 % of the mass of cement, and the additive-aeration – in the amount of 0,1 % of the mass of cement in all the components of concrete.
The application of engineering cementitious composites (ECC) – a specially developed class of cement-based material reinforced with fibers – allows to enhance the loading capacity, stability under static and dynamic influences, as well as durability of building structures due to controlled cracking process. The design of engineering cementitious composites is based on the concept of micromechanics, which includes the strength and energy criteria of deformation strengthening throughout the wide range from the macro- to the nanostructural level.
Every construction is influenced by different factors during operation. As a result, there are various defects and damage of these elements, which affects their operating condition. One of such defects is the corrosion of the working rebar. Investigation of samples with corrosion is a complicated and labor-intensive process. Instead of corrosive effects, we perform controlled valves of damaged. In this way, we obtained experimental samples with a fixed value of reducing the diameter of the valve.
In many countries (Japan, USA, China, Poland, etc.) the studies of the influence of laser radiation on the surface of various building materials are being carried out for a long time, including the military purposes. Most attention has been paid to the interaction of laser radiation with the surface of metals.
Досліджено взаємозв’язок між утворенням вищербин на поверхні кочення мо- дельних коліс і циклічною тріщиностійкістю сталей з нітридним зміцненням. Показано, що нітридне зміцнення колісних сталей позитивно впливає на опір пошкодженості поверхні кочення модельних коліс. Для підвищення роботоздатності колісних сталей з нітридним зміцненням зазначена необхідність оптимізації їх хімічного складу, забезпечуючи вміст вуглецю в інтервалі 0,50...0,55 % за вмісту ванадію 0,08...0,12 % і азоту 0,008...0,015 %.
Описано особливості локального підсилення електричного поля, а також електричних, механічних і термічних напруженостей у твердому діелектрику в залежності від конфігурації його провідних мікровключень. Проведено аналіз умов збільшення максимальної напруженості поля, напруженого об’єму, електромеханічних тисків, сил і густини повного струму в діелектрику як основних факторів, що визначають детерміновані та стохастичні процеси його деградації в збуреному гармонічному електричному полі.
The results of studies of the impact strength, temperature factors and parameters of cutting tool geometry on the formation of the stress-strain and thermodynamic state of surfaces with different types of engineering materials in the cutting process are described in the article. Analysis of simulation modeling of power, temperature and deformation parameters is the basis for making of forecasting models of influence of the structure and process parameters on the formation of complex operational properties of the product.
There is investigated the effect of carbonate-containing and sulfate salt processing wastes on the properties of cementitious systems and aerated concretes based on them.
In this article describes theoretical and experimental research of contact seams in the repair or strengthening concrete elements using concrete, sprayed-concrete anchors and substrate binding.