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Leonid Dvorkin

Bio: Leonid Dvorkin is an academic researcher. The author has contributed to research in topics: Cement & Superplasticizer. The author has an hindex of 6, co-authored 18 publications receiving 136 citations.

Papers
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Book ChapterDOI
01 Jan 2016
TL;DR: In this article, the sustainability of gypsum products during their life cycle is considered, including the energy efficiency of different manufacturing technologies, the use of industrial wastes containing calcium sulphate dihydrate as substitutes for natural gypsuma, and recycling of the wastes from gypsume-based construction materials (plasterboards, moulds) where they arise.
Abstract: In recent years, interest has been growing in the use of gypsum as one of the most sustainable mineral binders. This chapter covers a range of gypsum products based on different modifications of gypsum binders. The sustainability of gypsum products during their life cycle is considered. A sustainable life cycle includes the energy efficiency of different manufacturing technologies for gypsum products, the use of industrial wastes containing calcium sulphate dihydrate as substitutes for natural gypsum and recycling of the wastes from gypsum-based construction materials (plasterboards, moulds) where they arise.

65 citations

Journal ArticleDOI
TL;DR: In this paper, a concrete design objective function is proposed to obtain the required concrete strength by minimizing the cost of the most unsustainable concrete components, like cement, metakaolin and superplastisizer.

40 citations

Journal ArticleDOI
TL;DR: In this article, the influence of the main factors (water-cement ratio, fiber content, fineness and quantity of sand) on the concrete mixture stiffness, compressive and flexural strength of concrete is investigated.

28 citations

Journal ArticleDOI
14 Feb 2018
TL;DR: In this paper, the impact of phosphorgypsum as an admixture for clinker and non-clinker binders was investigated, and it was shown that using 2 to 2.5% of phosphoric acid as setting time regulator resulted in a similar physical and mechanical properties compared to mix made with natural gypsum.
Abstract: The increase of the consumption of gypsum products in construction industry with a limited amount of natural gypsum deposits requires alternative sources of gypsum-containing raw materials. In some countries which have fertilizers industry plants, the problem can be solved using industrial wastes, e.g. phosphorgypsum – a byproduct of fertilizers’ production. Kept in dumps over decades, phosphorgypsum is subjected to the chemical changes due to washing out impurities with rain and other natural factors. However, there are observed deviations of harmful impurities in dumped PG depending on its age., Phosphorgypsum of any age requires chemical treatment to neutralize remains of phosphorus and sulfuric acids, fluorine compounds. According to our researches one of the most simple and effective method of neutralization the impurities is using lime-containing admixtures. The paper presents results of laboratory tests of phosphorgypsum as a component of clinker and non-clinker binders. There were investigated the impact of phosphorgypsum as admixture for clinker binders to substitute natural gypsum. Neutralized phosphorgypsum can be applied as mineralizing admixture in calcination of Portland cement clinker. Adding 2 to 2.5% of phosphorgypsum as setting time regulator resulted in a similar physical and mechanical properties compared to mix made with natural gypsum. Another important area of phosphorgypsum application is sulphate activatoion of low-clinker blast-furnace slag cement (clinker content is less than 19%). According to results, the incorporation of phosphorgypsum as sulphate activator in cement has the better effect as natural gypsum. Other development has been carried out to modify the phosphorgypsum binder properties. Complex additive consisted of polycarboxylate-based superplasticizer and slaked lime permitted an increase mechanical properties of hardened phosphorgypsum binder due to significant a reduction of water consumption. Such modified binder can be used as partial or complete replacement of gypsum binder for filling cements and finishing plasters. It can substitute gypsum in non-clinker binders like supersulphated cements. There were also developed compositions of supersulphated cements based on low-alumina blast furnace slag and phosphorgypsum. Supersulphated cements were tested in normal-weight and light-weight concrete.

19 citations

Journal ArticleDOI
TL;DR: In this article, a theoretical analysis of the proposed parameters of the structure of concrete, which determine its frost resistance, is carried out and a calculation formula for predicting the frost resistance of concrete depending on the ratio of the volumes of open and closed pores in its structure.

14 citations


Cited by
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01 Jan 2016
TL;DR: The properties of concrete is universally compatible with any devices to read, and is available in the digital library an online access to it is set as public so you can download it instantly.
Abstract: Thank you for downloading properties of concrete. As you may know, people have look hundreds times for their chosen readings like this properties of concrete, but end up in malicious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they juggled with some malicious virus inside their computer. properties of concrete is available in our digital library an online access to it is set as public so you can download it instantly. Our digital library hosts in multiple locations, allowing you to get the most less latency time to download any of our books like this one. Merely said, the properties of concrete is universally compatible with any devices to read.

1,701 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of incorporating metakaolin (MK) on the mechanical and durability properties of high strength concrete for a constant water/binder ratio of 0.3 was presented.
Abstract: This study presents the effect of incorporating metakaolin (MK) on the mechanical and durability properties of high strength concrete for a constant water/binder ratio of 0.3. MK mixtures with cement replacement of 5, 10 and 15 % were designed for target strength and slump of 90 MPa and 100 ± 25 mm. From the results, it was observed that 10 % replacement level was the optimum level in terms of compressive strength. Beyond 10 % replacement levels, the strength was decreased but remained higher than the control mixture. Compressive strength of 106 MPa was achieved at 10 % replacement. Splitting tensile strength and elastic modulus values have also followed the same trend. In durability tests MK concretes have exhibited high resistance compared to control and the resistance increases as the MK percentage increases. This investigation has shown that the local MK has the potential to produce high strength and high performance concretes.

190 citations

01 Jan 1928
TL;DR: In this article, the authors discuss the need for accurate measurement of all materials and the need to find a consistent measure for all materials in a given volume of concrete and a consistent ratio of concrete to mixing water.
Abstract: THE STRENGTH OF CONCRETE MADE FROM SOUND, DURABLE MATERIALS DEPENDS UPON THE EXTENT TO WHICH THE SOLID PARTICLES ARE BONDED TOGETHER AND THE AMOUNT OF SOLID MATERIALS IN THE CONCRETE. THE BOND DEPENDS UPON THE PROPORTION OF CEMENT IN A GIVEN QUANTITY OF CONCRETE AND THE AMOUNT OF MIXING WATER. USING THESE BASIC PRINCIPLES SEVERAL METHODS FOR DESIGN ARE AVAILABLE. IN ANY CASE, THE MAINTENANCE OF A CONSTANT RATIO OF CEMENT TO MIXING WATER IS ESSENTIAL TO UNIFORMITY OF RESULTS. THE NEED FOR ACCURATE MEASUREMENT OF ALL MATERIALS IS EMPHASIZED AND ADEQUATE METHODS ARE DESCRIBED. AN EXAMPLE OF THE USE OF THE MORTAR-VOID METHOD OF DESIGNING TO MEET AN UNUSUAL CONDITION IS INCLUDED.

106 citations

Journal ArticleDOI
TL;DR: For a given strength grade, the optimum paste consisting of cement, fly ash and slag, and the optimum ratio among paste, fine aggregate and coarse aggregate were optimized using the simplex centroid design method based on rheological properties.
Abstract: The primary goal of concrete mixture design is to strike a balance among workability, compressive strength, durability, economic efficiency and sustainability. In this paper, for a given strength grade, the optimum paste consisting of cement, fly ash and slag, and the optimum ratio among paste, fine aggregate and coarse aggregate were optimized using the simplex centroid design method based on rheological properties. Results showed that the optimum content of total cementitious materials in concrete could be obtained according to the relationships between the workability, yield stress, plastic viscosity and the paste volume fraction. The optimum replacement of supplementary cementitious materials could be determined according to the rheological properties and compressive strength of concrete with ternary cementitious components. It is an effective way to optimize the mixture design of concrete based on the rheological properties using the simplex centroid design method.

80 citations

Journal ArticleDOI
TL;DR: In this article, a study concerning an automatic determination of distribution of steel fibres in self-compacting concrete (SCC) is presented, where the determination of fiber distribution is required to assess any relationship between those features and casting methods of concrete elements.

66 citations