DRY MIXTURES

[:ru]Белов В. В.[:en]Belov, V. V.[:] [:ru]д. т. н., проф., проректор по инновационному развитию ФГБОУ ВО «Тверской государственный технический университет», заведующий кафедрой производства строительных изделий и конструкций, Тверь, Россия[:en]Dr. Eng. Sc., professor, vice-rector of Tver State Technical University, Head of the Department of Building Products and Structures Manufacturing, Tver, Russia[:]

Alitinform №5 (06) 2008 г. 80-94 p.

Abstract

Modern residential construction technologies involve use of new methods, effective construction materials that provide influence onto life period of buildings and level of comfort of residential space.

These issues are connected with concrete modification methods, use of dry mixes and construction units in which various modifying additives are applied. At that, quality is improving while the overall cost of construction goes down. Transfer to the use of dry pack mortar in foreign countries happened several decades ago, thanks to their advantages, such as convenient method of delivery and stock of dry mixtures at a construction site, improved quality of construction works, reduction of loss and transportation costs, readiness for application, availability of delivery at temperature below 0°C, and others.

Analysis of today’s situation in production of dry mixes shows that their range practically does not include mineral heaving mixes suitable to fill multi-layer framing constructions or for other heat insulating purposes both in a process of construction, and in a process of buildings exploitation. Imported materials of this type are expensive and frequently manufactured with polymer binding agents, they can be inflammable, and do not meet requirements of durability set to main bearing elements of stone buildings.

Heat consumption for buildings heating in Russia is three times as high as that in other countries with similar climate conditions. According to a classification generally accepted abroad, wooden houses are graded first by comfort as a residential space, and houses of cellular (porous) concrete occupy the second place. Europe is streets ahead Russia by per capita production of cellular concrete. 113 European plants produce 18 mln. m3 of aerated concrete and gas silicate a year. Forced urge to overtake Europe, plus introduction of strict heat insulation standards (construction norms and specifications SNiP 23-02-2003) in Russia, provides a powerful impact for production of cellular concrete products, both autoclave-cured and non-autoclave. The latter gets the second birth, after 1950s, this «renaissance» comes from relative easiness of non-autoclave concrete production technology, low metal and energy consumption of equipment for its manufacturing and, consequently, low level of investments to set up production. This all resulted in mass emergence of small producers of foam concrete and simple equipment for its production. Russian market of non-autoclave aerated concrete cannot provide quality stability, because many producers use dubious equipment and technology. Currently, there is a need for production of non-autoclave aerated concrete of high quality, both for cast-in-place construction, and for concrete products. This purpose can be reached on account of use of aerated concrete manufactured from dry aerated concrete mixes. It is sufficient to stir the mix with a necessary amount of a liquid component, and then place the received mixture into a form or into a separated site. As a result, aerated concrete of high quality that meets up-to-date requirements can be obtained rapidly. This is why creation of high-quality dry aerated concrete mixes for production of aerated concrete is a problem of high importance.