В статье описаны явления влагопереноса в системе «стекловолоконная арматура-цементный раствор» на стадии твердения и структурообразования композита. Для получения представленной математической модели влагопереноса при формировании цементной матрицы использованы уравнения математической физики, уравнения нестационарного массопереноса и дифференциальные уравнения массопроводности параболического типа. Рассмотрено влияние на процессы влагопереноса в системе «стекловолоконная арматура-цементный раствор» условий твердения композита: при отсутствии внешнего массообмена; при испарении влаги с поверхности, когда волокно не поглощает воду из цементной смеси, и при одновременном испарении влаги с поверхности и поглощении воды волокном. Полученная физико-математическая модель влагопереноса для системы «цементный раствор-стекловолоконная арматура» позволяет учитывать изменение водоцементного отношения на стадии твердения композита и устанавливать его влияние на структурообразование композита, на процессы самоуплотнения бетона, на его деформативные и эксплуатационные характеристики, а также на структурно-фазовый состав бетона. Математические модели дают возможность устанавливать необходимое водоцементное отношение для получения композита с заданными характеристиками, такими как прочность на сжатие и на растяжение при изгибе, трещиностойкость, плотность, пористость, коррозионная стойкость. Сформулированная физико-математическая задача может быть решена для частных случаев методом микропроцессов, что позволит произвести расчёты прочностных характеристик композита и осуществить численный анализ показателей долговечности и надёжности изделий и конструкций из армированного стекловолоконная арматурой бетона.

The article concerns with the prospects of using the phenolphthalein test solution in the practice of surveying concrete and reinforced concrete building structures in planta. The problem of the study is the limits of application of the phenolphthalein test solution on the pH level of the determined concrete (the indicator works only at 8≤rn≤10). There is a need of expanding the phenolphthalein test solution application. In order to determine the different pH zones of concrete we have to modernize the method by adding other indicators to phenolphthalein. The standard phenolphthalein test solution does not allow a high degree of accuracy in determining the most sensitive to carbonation boundary zones of concrete. We proposed to modernize the phenolphthalein sample solution by using additional acid-base indicators alizarin and neutral red. We presented the results of experiments on measuring the surface neutralized layer of concrete by alcoholic solutions of acid-base indicators alizarin and neutral red on different age and size concrete samples. As a result, one of the proposed indicators (neutral red) allows to expand the phenolphthalein test solution application. We compared the results obtained by the traditional and modified methods. According to it, the proposed modified method is more accurate one.

The article describes the phenomenon of moisture transfer in the system “composite non-metallic reinforcement – cement mortar” at the stage of hardening of the composite. The processes of moisture transfer occurring during the structure formation have an impact on the water-cement ratio of the cement mixture. The deformation and operational characteristics of cement concrete, its structural and phase composition, porosity, density and corrosion resistance depend on the water-cement ratio. To obtain a mathematical model of moisture transfer in the formation of the cement matrix, the equations of mathematical physics, the equations of unsteady mass transfer and the differential equations of mass conductivity of parabolic type are used. Mathematical models of mass transfer processes make it possible to predict the change in the characteristics of the composite at the hardening stage and to obtain concretes with specified properties. The presented physical and mathematical model of moisture transfer for the system “cement concrete – composite reinforcement” allows to take into account the change in water-cement ratio at the stage of hardening of the composite and to establish its influence on the structure formation of the composite and its performance characteristics. The formulated physical and mathematical problem can be solved for special cases by the method of microprocesses.

Objective. At present, increased requirements are imposed on waterproofing materials used in seismic hazard zones. The aim of the study is to assess the possibility of using LOGICBASE™ polymer membranes in regions of increased seismic activity in the Russian Federation.Method. The mechanism of operation of polymeric membranes in foundation structures under conditions of constant displacement and friction is considered. Experiments were carried out to determine the coefficient of friction according to the method of state standards on a tensile testing machine MIRK-1000K. Samples of a round shape made of polymeric membranes were studied on a special multiaxial stretching device in accordance with the requirements of state standards.Result. Multiaxial tensile testing of LOGICBASE™ V-SL polymeric membranes revealed that the maximum tensile strength of the samples was 6948.22 kPa (~ 6.95 MPa), and the elongation of the samples at break was 113.89%. The coefficient of friction in the system "polymer waterproofing material - concrete structure" was determined under conditions of increased seismic activity according to the MSK-64 scale.Conclusion. According to the studies, it was concluded that PVC membranes for engineering waterproofing can be used in construction areas with seismicity up to 9 points inclusive on the MSK-64 scale.

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