CC BY
14
UDC 666.972.16(088.8)
M. K. Kuderin1, R. Berndston2
*Doctor of engineering sciences, professor, S. Toraighyrov Pavlodar State University, Pavlodar, Kazakhstan; 2professor, Lund University, Sweden
CONCRETE DURABILITY MODIFYING ADMIXTURE
The work deals with complex chemical concrete admixtures, established to elaborate concretes of high durability and endurance under high concrete mobility.
Key words: concrete, cement, plasticizer, concretion, durability, supplement, water content, waste products.
INTRODUCTION
Periodically, many researchers have been focusing a great deal of attention on the issue of concrete strength development. Moreover the prevailing aim of this very sphere of investigations is considered to be the elaboration of various structure modifying methods, optimum in the way the void space arranged, if possible less expensive than the ones already known.
MAIN PART
Authors present the complex chemical admixture due to which concretes of extra high water- and frost resistance, at relatively slump of 10-12 cm, can be obtained.
The complex concrete-oriented admixture, contains sulfite-leavenous brew, natrium/ sodium salt of non-organic acid, and additional emulsified mixture of mineral oils in terms of following masses ratio, %:
sulfite-leavenous brew 13-24;
natrium salt of non-organic acid
(sodium nitrite, sodium nitrate, sodium sulphate) 19-29;
emulsified mixture of mineral oils 47-68.
In this very suggested composition of complex admixture, the emulsified admixture of oil minerals is applied to be the plasticizing and air-entertaining agent containing by weight % synthetic residues of thermal polymerization 90-99, the post proceeding of an acetylation process 1-10.
The contribution of the emulsified oil minerals incorporation to the concrete mix can be explained in focus of various chemical reactions taking their place. Particularly indene, fulvene and stilbene forming the admixture and easily interacting with original portland cement (OPC) hydration products, on their hand form sparingly soluble doubled hydrate salts which excert gas-like H2. Fluorene after being oxidized with atmospheric O2, transfers to fluorenone or participating in similar displacement reactions, forms resistant compounds generating H2 respectively. The very hydro-carbon molecules provide concrete mixture with entertaining of non-polar air vials, determine their dispersion and stabilization in the cement paste, for hydrocarbons plus H2 plasticize the
ISSN 1680-9165. №3-4, 2016 r.
mixture. Having uniformly spread in the concrete mixture and being conventionally isolated (actually air vials are not totally isolated, but less penetrative for water and solutions from without) pores act as peculiar absorbers and contribute the concrete frost-and water-resistance dramatically.
Since the prevailing distinguishing attribute of emulsified hydrocarbon compounds occurs to be their utter molecules' asymmetry, which is balanced to provide their pronounced unwettability, thus chemical adsorption is the first stage only, and can be followed by chemisorptions or chemical reaction in the volume/medium of particles. There is a good reason to believe that admixture declines the interphase energy and facilitates disaggregation (deflocculation) of the particles. At the same time great amount of immobilized water is being disengaged and this very water is to provide the plasticizing effect. Moreover the adsorption layers themselves have capacity for flattening the surface roughness of particles thus declining the mutual friction coefficient. Due to this dramatically decreases the surface tension between mediums of liquid and air thus declining the effect of additional airentertaining.
The following components were used as constiuents/source materials for the complex admixture:
- sulfite-leavenous brew (SLV), meeting the requirements of Branch Standard -3183-83, the by-product of sulfite waste liquor processing into nutrient or average yeast;
- natrium/sodium salt of non-organic acid represented by one of the following admixtures: sodium chloride [all-Union State standard 13830-84], sodium sulfate [all-Union State standard 4166-66], sodium nitrite [all-Union State standard 4197-74];
- emulsified mixture of mineral oils resulted via homogenization of gas-oil-kerosene fraction pyrolysis intermediates, synthesized at to 670 Co over a superheated up to 610°C steam.
To compare the effect of represented and yet known admixtures standard concrete mixes were made with slump of 10 cm. Specimens were tested in terms of/according to current standards/norms of durability [all-Union State standard 10180-78], frost resistance [all-Union State standard 10060-87], and water [non-]permeability [all-Union State standard 12730.0-78]
The emulsion is made in a certain amount of mixing water in electric mixers (20003000 rpm), providing its high dispersity and stability. Sulfite-levenous brew maintains the function of emulsifier/emulgator . (The) emulsion-mixing water ratio is incorporated to a dry mix of binding material and fillers during the process of concrete mixture elaboration on continuous/non-stoppable mixing for 1.5 -2 minutes.
The suggested issue is supposed to be solved via following solutions represented in Table 1.
Table 1 - The suggested issue is supposed to be solved via following solutions
№ Complex admixture/agent content and Suggested contents(ratios) Prototype
admixture-incorporated concrete properties 1 2 3
1 — sulfite-leavenous brew (SLV) 13 19 24 61
— sodium salt of non-organic acid 19 24 29 15
— sodium salt of oil-sulfite acids — — — 24
— emulsified mixture of oil products 68 57 47 —
2 Compressive strength breaking point, MPa
— at 28 days of moist curing 37,3 38,6 35,5 34,3
— at 180 days of moist curing 40,5 41,6 39,8 35,5
Flexture strength breaking point, MPa
— at 28 days of moist curing 3,8 3,98 3,76 3,55
— at 180 days of moist curing 4,3 4,54 3,99 3,69
3 Water resistance, MPa 1,4 1,3 1,1 0,7
4 Frost resistance, cycles 467 420 430 350
As it is seen from the Table 1 at 28 days of moist-curing, samples, made of concrete mixes and incorporated with the admixture of suggested content, as a fact reveal the compressive strength 21 % higher than of the ones being planned for concretes of this class/type and 9 % higher than the prototype. One can see the dynamics of compressive strength development further, at the age of 180 days. The compressive strength development at 180 days of moist curing was about 13 %. The frost resistance of concrete incorporated with suggested complex admixture was 19 % higher respectively and the water resistance was almost twice more then the ones of prototype.
Concretes incorporated with the suggested admixture can be successfully applied to industrial, civil, hydrotechnical and land-improvement engineering. Moreover they can be used in the following spheres of construction:
1) facing the canalization;
2) transport engineering;
3) establishing the bridge constructions and props;
4) monolith and prefabricated/combined tunnels.
CONCLUSION
Thus such incorporated concretes are to be of a great demand in constructions having high water- and frost-resistance requirements. The very admixture incorporated concrete mixes are of a great plasticity thus capable for being moved via pneumatic pavers and concrete pumps.
Material received on 12.12.16.
ISSN 1680-9165. №3-4, 2016 г.
М. К.. Кудерин1, Ронни Берндстон2
Бетонный бержттн кетеруге арналFан коспаларды езгерту
Ю. ТораЙFыров атындаFы Павлодар мемлекетлк университетi, Павлодар к., Казахстан; 2Лунд университетi, Лунд к., Швеция.
Материал 12.12.16 баспаFа тYстi.
М. К. Кудерин1, Ронни Берндстон2
Модифицирующая добавка для повышения долговечности бетона
1Павлодарский государственный университет имени С. Торайгырова, г. Павлодар, Казахстан;
2Лундский университет, г. Лунд, Швеция.
Материал поступил в редакцию 12.12.16.
Мацала цоспасыныц салыстырмалы жогары утцырлыц жогары бержтш бетондар мен твзiмдiлiгiн алуга мумктдж беретт, бетон цоспалары ушт кyрделi химиялыц цоспалар дамытудыц кейбiр багыттарын талцылайды.
В статье рассмотрены некоторые направления по разработке комплексной химической добавки для бетонных смесей, позволяющая получать бетоны повышенной прочности и долговечности при относительно высокой подвижности смеси.
УДК 669.183
М. К. Кудерин1, Г. М. Мажидов2, Г. Н. Каржаубаева3
:д.т.н., профессор, 2,3магистранты, Павлодарский государственный университет имени С. Торайгырова, г. Павлодар
ПРИМЕНЕНИЕ ПРОГРЕССИВНЫХ СТРОИТЕЛЬНЫХ ТЕХНОЛОГИЙ И СОВРЕМЕННЫХ КОНСТРУКТИВНЫХ СХЕМ ВОЗВЕДЕНИЯ ЗДАНИЙ
Применение прогрессивных строительных технологий и современных конструктивных схем возведения зданий, предполагает использование предварительно напряженных арматурных элементов.
Ключевые слова: монолитное строительство, инновационные технологии, предварительно напряженный элемент, постнапряжение, трещиностойкость.
ВВЕДЕНИЕ
В настоящее время усиливается тенденция повышения доли монолитных конструкций в общем объеме строительных работ. Мировая практика строительства показывает, что на сегодняшний день из существующих технологий возведения зданий и сооружений наиболее перспективным является именно монолитное строительство.
