The article describes the characteristics of belite sludge - large-tonnage waste of the aluminium industry. The ability of the sludge and sludge-rubbing materials to restore the damaged structure after re-compaction has been revealed. The influence of multiple transport loads on the nature of the sludge hardening and slurry materials in structural layers on an annular test bench under full-scale conditions has been investigated. It has been established that mobile loads have a positive effect on the nature of the hardening of these materials. After 20 months of operation, the strength of the sludge and sludge material on the sections under movement is 13.0% and 33.8% higher compared with the materials of the control sections. Consequently, there is no need to close the traffic immediately after the construction of pavement layers using sludge. In addition, it is not necessary to regulate the time after which the installation of a coating on a slurry base is allowed.
ВВЕДЕНИЕОдним из путей повышения долговечности дорожных конструкций является строитель-ство монолитных оснований дорожных одежд. Общеизвестно, что срок службы нежестких дорожных одежд с монолитными основаниями из материалов, обработанных минеральными вяжущими, в 1,5-2,0 раза больше чем с осно-ваниями из дискретных материалов [1]. Осо-бую актуальность при этом приобретает за-мена классических вяжущих (цемент, известь) на отходы промышленности, обладающие свойствами бесклинкерных медленнотвер-деющих вяжущих. К таким отходам относит-ся белитовый шлам -многотоннажный отход глиноземного производства, который без до-полнительного измельчения, за счет высокого содержания белита (С 2 S), может быть исполь-зован для устройства монолитных слоёв до-рожных одежд, как в естественном виде, так и в качестве вяжущего и структурообразующего реагента при укреплении каменных матери-алов и грунтов. В настоящее время изучены свойства шлама, разработаны рекомендации по использованию этого материала в дорож-ном строительстве, в том числе при отрица-тельной температуре воздуха [2][3][4][5]. В соот-ветствии с нормативными требованиями, при использовании для строительства монолитных слоев дорожных одежд медленнотвердеющих вяжущих, открывать движение построечно-го транспорта допускается в течение первых двух суток после их устройства [6]. Однако во-прос о влиянии транспортных нагрузок на ха-рактер твердения материалов дорожных осно-ваний, укрепленных медленнотвердеющими вяжущими, в том числе белитовым шламом, изучен недостаточно. Особую значимость это имеет при строительстве нефтепромысловых дорог в сложных гидрогеологических условиях где, как, правило, нет возможности обеспечить объезд строящегося участка основания или покрытия.Следовательно, изучение влияния много-кратных транспортных нагрузок на характер твердения шлама и шламоминеральных мате-риалов является актуальной научной и прак-тической задачей. СВОЙСТВА БЕЛИТОВОГО ШЛАМАБелитовый шлам образуется при производ-стве глинозема (оксида алюминия) из нефели-новых и бокситовых руд способом спекания. Из спека путем гидротермального выщелачи-вания выделяют глинозем, а пескообразный полупродукт -шлам по трубопроводу пода-ется в отвал. В результате технологического процесса производства глинозема происхо-
The paper describes the characteristics of belite sludge - a large-tonnage waste of alumina production. The influence of negative temperatures on the technological properties of the sludge was investigated. The regularities of sludge cooling during its excavation, long-term storage and in the technological process of structural layers’ construction in winter conditions have been studied. Recommendations have been developed for the construction of foundations (coatings) from sludge and sludge-mineral materials at temperatures below minus 20°C. The implementation of research results helps to prolong the construction season, reduce material consumption and increase durability during construction, reconstruction and repair of transport infrastructure objects.
Introduction. The physical and mechanical properties of belite (nepheline) sludge, a large-tonnage waste of alumina production, are given. The scope of its application is shown in the construction, reconstruction and repair of roads and airfields.Materials and methods. The data of theoretical and laboratory studies on the use of ground nepheline sludge as a binder for strengthening asphalt granulate, including at low temperatures, without antifreeze additives. The optimal dosages of finely ground sludge for strengthening asphalt granulate 10–15℅ have been determined.Results. The results of the experimental studies were confirmed during the production check during the construction of the pilot section of the foundation made of sludge granulometric concrete. The direction of further research is determined.
Introduction. Increasing the durability of road structures and extending the construction season for the installation of monolithic road pavements are urgent tasks. Non-rigid road pavements are of particular interest. Replacing the bases of granular materials (crushed stone, gravel, etc.) with monolithic ones reduces the material consumption of the road surface by 20-50%, the cost of construction works by up to 45% and increases the service life of roads by 1.5-2 times. The extension of the construction season for the installation of monolithic bases contributes to an increase in the pace of construction, a more rational use of road construction equipment, securing highly qualified specialists at the enterprise and reducing overhead costs. A multi-tonnage waste having independent binding properties is of particular interest, for example, belite sludge of alumina production. The article is devoted to a comprehensive study of the physical mechanical and technological properties of natural belite sludge in order to use it for the making of monolithic layers of road and airfield pavement in winter, without the introduction of antifreeze additives.Materials and methods. The freezing temperature of the belite sludge of minus 2 ° C was determined by the thermoelectric method. Its compactibility in the range of negative temperatures, the ability to restore the destroyed structure after re-compaction, the regularities of cooling of the material during technological operations for the construction of structural layers in winter are studied. The compaction was studied by pressing samples from sludge of optimal humidity, at its temperatures from 20 to minus 10°C. The study of the processes of structure formation of sludge and sludge crushed stone materials consisted in studying the kinetics of hardening of samples stored in climatic chambers that simulate changes in average monthly air temperatures in an annual cycle (from 20°C to minus 20°C) and in natural conditions (outdoors). In parallel, thermographic and electron microscopic studies of neoplasms in the hardening material were performed. To study the regularities of the cooling of the sludge layers, a laboratory experiment was conducted that simulates two-way (top and bottom) freezing of the material in a climatic chamber at temperatures of minus 10, minus 15 and minus 25°C.Results. A complex of unique physical chemical and technological properties of natural belite sludge has been identified, which consist in maintaining the initial density and activity after freezing, the ability of sludge and sludge crushed stone materials to harden at negative temperatures, a reduced freezing temperature of minus 2°C, good compaction in the range of negative temperatures (up to minus 6°C). The temperature and technological parameters of the sludge preparation for the production of works in winter are investigated. The regularities of sludge cooling in the technological process for the construction of structural layers in winter are studied. A technology has been developed for the making of monolithic layers of the road pavement made of belite sludge and crushed stone materials at negative air temperatures up to minus 20°C. The practical experience of the belite sludge use in the construction of roads in 2-4 road-climatic zones is summarized.
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