Technology of monolithic construction with the use of clinker-effective concretes modified by superplasticizers of new generation
Students Name: Hrabchak Nataliia Volodymyrivna
Qualification Level: magister
Speciality: Urban Construction and Economy
Institute: Institute of Civil Engineering and Building Systems
Mode of Study: part
Academic Year: 2020-2021 н.р.
Language of Defence: ukrainian
Abstract: SUMMARY Grabchak N.V., Sanitsky M.A. (head). "Research of modified concretes based on polyfraction aggregates and Portland cements of PJSC "Ivano-Frankivskcement". Master’s thesis. – Lviv Polytechnic National University, Lviv, 2020. The master’s thesis is devoted to the development of high-strength concrete based on Portland cement PC II/A-B-500R-N PJSC "Ivano-Frankivskcement" by designing the composition using polyfraction aggregates and polymer modifiers. The advantages of using such concretes are the reduction of construction time. An important problem is to ensure the construction of high-strength concrete that meets the strength classes C35 / 45…C50 / 60. Such concretes are especially necessary for special purpose structures (tunnels, bridge structures, etc.). Usually, the production of high-strength concrete is associated with the need to use high-quality aggregates, which are characterized by high grain strength and provide minimal water consumption and voids. One of the most important factors for obtaining high-strength concrete, capable of providing both mechanical properties and durability of the structure, is a low (in the range of 0.25-0.35) water-cement ratio (V / C). In this case, polymer-based hyperplasticizers, which are characterized by a water-reducing effect of 25-35%, can show special efficiency. By providing the required values of V / C, it is possible to obtain modified concretes of high strength. Object of research – there are processes of change of properties of the modified concretes on the basis of Portland cements and polyfractional fillers at the expense of introduction of polymeric additives The subject of research – concretes based on Portland cement PJSC "Ivano-Frankivskcement" and polyfraction aggregates using polymer additives. The purpose of the research is to study the effect of polymer additives and polyfraction aggregates on the physical and mechanical properties of concrete, optimization of their compositions. Research results: A review of literature sources on the use of high-strength concretes and concretes on polyfraction aggregates. The characteristic properties of high-strength concretes are considered and the relevance of the use of such concretes in construction is determined. The grain composition of a large aggregate of different sizes was selected to form the most dense matrix of modified high-strength concretes. The compositions of modified concretes using Portland cement CEM II / A-LL 42,5R PJSC "Ivano-Frankivsktsemen" with the addition of polyfraction aggregates and polymer-type superplasticizer by the method of mathematical planning of the experiment were designed and investigated. Based on these chart models, it is concluded that the most optimally effective composition is at the amount of consumption of the polymer additive 0.7 wt.% And the ratio of polyfraction coarse aggregate fractions 5-10 and 10-20 mm, respectively, 20 and 80%. It is shown that modified concrete mixtures with high early strength in combination with polymer additives are effective when used in construction. The economic effect is calculated, which made it possible to reduce the consumption of cement and reduce the cost of the finished concrete mixture by 7% due to the introduction of a complex polymer additive. Keywords: modified concrete, polyfraction aggregate, polymer additive, strength