TYPES OF ANTIFREEZE ADDITIVES IN REINFORCED CONCRETE PRODUCTS AND STRUCTURES USING REINFORCEMENT

Аннотация

In the construction of prefabricated monolithic structures, in the production of concrete and reinforced concrete structures at construction sites and landfills, it is possible to monolithize the seams of prefabricated structures, concrete with antifreeze additives despite low temperatures (up to -25 °C). In addition, when concreting in winter, care should be taken when using special types of concrete: those used in high-strength and aggressive environments. It is well known that premature freezing of concrete, as well as the use of certain admixtures, can affect the performance characteristics ofconcrete, particularly itsdurability. Key words: Precast-monolithic, construction, reinforced concrete, reinforced concrete construction, antifreeze, concrete, temperature, freezing. Аннотация: При строительстве сборно-монолитных конструкций, при производстве бетонных и железобетонных конструкций на строительных площадках и свалках возможна монолитизация швов сборных конструкций, бетона с антифризными добавками, несмотря на низкие температуры (до -25 °С). ). Кроме того, при бетонировании зимой следует соблюдать осторожность при использовании специальных видов бетона: применяемых в высокопрочных и агрессивных средах. Общеизвестно, что преждевременное замерзание бетона, а также применение некоторых добавок могут повлиять на эксплуатационные характеристикибетона,в частности наего долговечность. Ключевые слова: Сборно-монолитное строительство, железобетон, железобетонные конструкции,антифриз,бетон,температура,замерзание. Monolithic is widely spread in modern construction technologies in the world. Concreting of monolithic structures is also possible in winter with certain restrictions and recommendations. With the use of additives, concrete and mixtures can be used for: construction of prefabricated monolithic structures, monolithic joints of prefabricated structures in the production of concrete and reinforced concrete structures on construction sites and landfills. Despite the low temperature (up to -25 °C), concrete with some antifreeze additives gradually but systematically gains strength due to the hydration of cement, however, according to a number of authors, cement hydration is not achieved. Occurs at temperatures below zero, and therefore hardening of concrete does not occur. Today, almost any structure can be concreted at sub-zero temperatures. Constructions built in wintercan bedivided into two groups: 1. The use of thin-walled structures (floor slabs, columns, walls), heating and accelerating additives allows to obtain minimum and insomecases class strength already onthe2ndday. 71 INTERNATIONAL MULTIDISCIPLINARY JOURNAL FOR RESEARCH & DEVELOPMENT SJIF2019:5.2222020:5.5522021:5.6372022:5.4792023:6.5632024:7,805 eISSN:2394-6334 https://www.ijmrd.in/index.php/imjrd Volume11,issue07(2024) 2. When concreting massive structures (foundation slabs), artificial heating of concrete and exothermic binder can be used, which allows concrete to "self-heat" to a temperature of about 50- 600C with proper preparation offorms. In addition, when concreting in winter, care should be taken when using special types of concrete: those used in high-strength and aggressive environments. It is well known that premature freezing of concrete, as well as the use of certain admixtures, can affect the performance characteristics of concrete, particularly its durability. The use of antifreeze additives in reinforced concrete products and structures using reinforcement is also limited, because sometypes ofadditives (for example, chlorides) cancause corrosion. Antifreezeadditives and theircompatibility withother materials. Effect ondurabilityof concrete: As mentioned above, when concreting with the use of chemical additives, taking into account the field oftheir application, antifreezeadditives are divided into several groups: - additives (electrolytes, alcohols) that lower the freezing point of free water in concrete and have aslight effect onthehardening kinetics ofconcrete. - additives (potassium, chlorides, nitrates, nitrites, urea) that have the properties of antifreeze and are abletoaccelerate thehardening and hardening processes ofcement. - substances that have weak antifreeze properties, but accelerate the hardening and hardening of cement; at the sametime, such additives cause strong heat generation and hardening ofconcrete at theinitialstage ofsetting theconcrete mixture(iron III andaluminum sulfates). - in modern conditions, you can often find complex antifreeze additives based on a plasticizer with antifreeze and accelerator properties, which allows to simplify the technological process of concretemixture production tosome extent dueto theuse ofoneadditional dispenser. Accordingly, today it is possibleto distinguish many different materials used for the production of antifreezeadditives (AA) (Table 1). Table 1 Types of substances used intheproduction ofAA: Substance Designation Chemical formula Sodiumchloride NaCh NaCl Sodiumnit