The Effect of Additives Including Metakaolin on the Freeze Resistance of Concrete

2016 ◽  
Vol 843 ◽  
pp. 263-268
Author(s):  
A.A. Kirsanova ◽  
V. Thiery ◽  
L.Ya. Kramar
Keyword(s):  
Phase Composition ◽  
Cement Stone ◽  
Optimum Amount ◽  
Freeze Resistance ◽  
Optimal Amount ◽  
Degree Of Hydration ◽  
Effect Of Additives ◽  
Research Studies

With the help of research studies on the freeze resistance of concrete with complex additives containing metakaolin it is found that its optimum amount with microsilica and plasticizing agents can provide concrete with high freeze resistance of F11000 and more. The use of metakaolin – superplasticizing admixture contributes to a slight increase of freeze resistance of concrete only due to the consolidation of its structure as a result of increasing the degree of hydration of main minerals of concrete С3S and β-С2S under the influence of metakaolin. It is proved that the optimal amount of metakaolin together with superplasticizing admixture helps to form the phase composition of cement stone from highly basic hydrosilicates and stable hydroaluminates. The use of overdosed metakaolin leads to appearance of a great number of metastable hydroaluminates in the cement stone which makes it inefficient for the production of freeze-proof concrete.

scholarly journals Alkali activated cements mix design for concretes application in high corrosive conditions

2018 ◽  
Vol 230 ◽  
pp. 03007 ◽  
Author(s):  
Oleksandr Kovalchuk ◽  
Valentina Grabovchak ◽  
Yaroslav Govdun
Keyword(s):  
Corrosion Resistance ◽  
Phase Composition ◽  
Mix Design ◽  
Cement Stone ◽  
Hydration Products ◽  
Alkali Content ◽  
High Corrosion Resistance ◽  
Corrosion Resistant ◽  
High Corrosion ◽  
Alkali Activated

This paper covers the results of development of corrosion resistant ash alkali-activated cements based on regulation of phase composition of the hydration products through changing the alkali content, content of calciumcontaining cement constituents resulting in the increase strength and density of the cement stone. The results of study suggested to conclude that the cement compositions with predominance in the hydration products of weakly soluble low basic hydrosilicates of calcium, hydrogarnets and minerals similar to natural hydroaluminates exhibited the highest corrosion resistance. The results of comparison suggested to draw a conclusion that the alkali-activated cements Types APC III-400 and ACC V-400, according to National Ukrainian Standard DSTU B V.2.7, had high corrosion resistance compared to that of OPC, thus allowing to recommend the developed cements for the concretes intended for use in aggressive environments, inclusive of sodium and magnesium sulphates and others. Coefficients of corrosion resistance of concretes are higher than 1 after even 42 months.

Effect of Metakaolinite on Properties of Alkali Activated Slag Materials

2018 ◽  
Vol 761 ◽  
pp. 69-72 ◽  
Author(s):  
Łukasz Kotwica ◽  
Marcin Chorembała ◽  
Ewa Kapeluszna ◽  
Piotr Stępień ◽  
Jan Deja ◽  
...  
Keyword(s):  
Phase Composition ◽  
Phase Formation ◽  
Alkali Activated Slag ◽  
Degree Of Hydration ◽  
Activated Slag ◽  
Alkali Activated

Metakaolinite was introduced to alkali activated slag mortars and pastes. Properties of fresh and hardened mortars as well as phase composition and microstructure of hardened pastes were investigated. Introduction of metakaolinite both as addition as well as substitution of slag results in severe decrease in strength of the mortars. SEM observations revealed, that metakaolinite presence results in much less compacted microstructure comparing to reference slag paste. The reason for that are differences in phase composition as determined with XRD. C-S-H phase formation is retained in the presence of metakaolinite and thus degree of hydration of slag is decreased comparing to reference, slag paste.

The Increase of Hydration Activity of Portland Cement by Additives of Crystalline Hydrates

2019 ◽  
Vol 974 ◽  
pp. 195-200
Author(s):  
Yury R. Krivoborodov ◽  
Svetlana V. Samchenko
Keyword(s):  
Phase Composition ◽  
Portland Cement ◽  
Cement Hydration ◽  
Bound Water ◽  
Cement Stone ◽  
Pulsation Apparatus ◽  
Rotary Pulsation Apparatus ◽  
Calcium Hydrosilicates ◽  
Crystalline Hydrates

The article presents the results of a study of the effect of synthesized microdisperse additives of crystalline hydrates based on calcium sulfoaluminates on the properties of cement stone. The effectiveness of the use of a rotary pulsation apparatus (RPA) to obtain microdispersed additives is identified. The possibility of accelerating the hardening of cement stone by entering microdispersed additives into its composition is shown. It has been established that in the presence of microdispersed additives of crystalline hydrates in the cement stone, the phase composition of hydrate tumors changes, the amount of calcium hydrosilicates and ettringite increases, the porosity decreases and the strength of the cement stone increases. This provision is confirmed by the increase in the degree of cement hydration, the amount of bound water in all periods of hardening of the stone. It is proposed to use microdisperse additives, which play the role of primers for the crystallization of ettringite and calcium hydrosilicates, to increase the strength of cement stone in the early stages of hardening.

scholarly journals Research of the mineral additives influence on aggregative stability of foam concrete mixture

2021 ◽  
Vol 2131 (4) ◽  
pp. 042034
Author(s):  
E Bartenjeva
Keyword(s):  
Aggregate Stability ◽  
Stable Structure ◽  
Concrete Mixture ◽  
Aggregative Stability ◽  
Cement Stone ◽  
Foam Concrete ◽  
Effect Of Additives ◽  
Modifying Effect ◽  
The Stability ◽  
Mineral Additives

Abstract An effective method for increasing the aggregate stability of non-autoclave heat-insulating foam concrete is proposed. This material is prepared using a two-stage technology on a turbulent-type installation. An increase in the stability of the foam in the mortar mixture by 9.5-23% has been established. An increase in the viscosity of the foam concrete mixture by 13.5% was revealed. Wollastonite and diopside are actively involved in the formation of a stable structure of foam concrete and are structurally modifying centers. The introduction of mineral additives contributes to the formation of a homogeneous stable structure of non-autoclave foam concrete. Thus, an increase in the stability of the cellular system in the technology of non-autoclave cement-ash foam concrete is possible due to the control of the processes of structure formation when using dispersed mineral additives of wollastonite and diopside. Due to the structural-modifying effect of additives as crystallization centers for neoplasms, a more complete hydration of the cement and a strong contact of the additives with the cement stone should be ensured

The Effect of Thiourea Additive to Elimination of the Iron Dissolved in Flux Solution of Hot Dip Galvanizing Process

2012 ◽  
Vol 538-541 ◽  
pp. 186-189
Author(s):  
Kyung Man Moon ◽  
Min Seok Oh ◽  
Jong Pil Won ◽  
Myung Hoon Lee ◽  
Yun Hae Kim
Keyword(s):  
Structural Steel ◽  
Current Density ◽  
Manufacturing Process ◽  
Iron Ion ◽  
Applied Current ◽  
Optimum Amount ◽  
Applied Current Density ◽  
Dissolved Iron ◽  
Effect Of Additives ◽  
The Cost

Hot dip galvanizing is being widely used to the numerous constructional steels such as a guard rail of high way, various types of structural steel for manufacturing ship and for some other fields etc.. Recently, the cost of zinc is getting higher and higher, thus, a proper manufacturing process should be developed possibly to reduce the cost of production. one of hot dip galvanizing process, that is, flux solution immersion process is very important to control more effective coating. However, flux solution is deteriorated with increasing its using time because dissolved iron from structural steel due to continuous flux treatment was increasingly increased, which is resulted in coating badness and increment of dross. In this study, the effect of additives to elimination of iron dissolved in flux solution was investigated with four types of inner solution, that is, solution of inner barrel was filled with seawater, NaOH, NH4Cl, including parameters of amounts of thiourea(0.2,0.4 ,0.6 and 0.8g) and electrolysis experiment was carried out with applied current density at 20mA/cm2. The best effect for elimination of iron from flux solution is considered that inner barrel with separator should be filled with solution different from original flux solution which contained in iron ion, that is, its inner solution should be composed with seawater added with additives such as thiourea(0.4g), NaOH(0.2 g) and NH4Cl(10g). In particular, we can see that the optimum amount of thiourea to extract effectively iron from flux solution is 0.4g.

scholarly journals Mechanochemical activation of batch during fabrication of highly-porous cordierite materials based on natural oxide compounds

2006 ◽  
Vol 38 (3) ◽  
pp. 203-210 ◽  
Author(s):  
V.N. Antsiferov ◽  
S.E. Porozova ◽  
V.I. Karmanov
Keyword(s):  
Phase Composition ◽  
Infrared Spectroscopy ◽  
Mechanochemical Activation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Effect Of Additives ◽  
Composition Variation ◽  
Natural Oxide ◽  
Highly Porous ◽  
Porous Cordierite

Using X-ray diffraction analysis and infrared spectroscopy techniques, the effect of additives on phase composition variation during mechanochemical activation of a kaolin-containing cordierite batch was investigated. It was shown that introduction of Trilon B permits fixing of the start of cordierite synthesis already during batch activation. It was established that mechanochemical activation of a cordierite batch doped with Trilon B results in an increase of the strength of cordierite samples prepared by polymer matrix duplication.

scholarly journals CHANGES IN THE STRUCTURAL AND PHASE COMPOSITION OF CEMENT CONCRETE DURING MICROBIOLOGICAL CORROSION

2021 ◽  
Vol 6 (11) ◽  
pp. 106-113
Author(s):  
K. Strokin ◽  
D. Novikov ◽  
V. Konovalova ◽  
N. Kasiyanenko
Keyword(s):  
Compressive Strength ◽  
Phase Composition ◽  
Portland Cement ◽  
Cement Stone ◽  
Cement Concrete ◽  
Microbiological Corrosion ◽  
Crystalline Phases ◽  
X Ray ◽  
Calcium Hydrosilicates ◽  
Black Mold

The article considers the change in the structural and phase composition of cement stone made of Portland cement of the CEM I 42.5 N brand in the process of bacterial and fungal corrosion during 6 months when humidified. The X-ray images of cement stone show peaks that characterize the non-hydrated components of Portland cement alite, belite, tricalcium aluminate, four-calcium aluminoferrite and gypsum. By the method of X-ray phase analysis, it is found that during microbiological corrosion, the content of all phases of cement stone decreases. The aspergillus niger van Tieghem fungi have a stronger effect on the structural and phase composition of cement stone. Fungal microorganisms destroy the crystalline phases and absorb amorphous phases – calcium hydrosilicates C-S-H (I) and C-S-H (II) and tobermorite. When bacteria Bacillus subtilis affects the cement stone, the content of the calcite phase increases, which is a product of corrosion, while the action of black mold reduces the intensity of CaCO3 peaks. A decrease in the content of low-base calcium hydrosilicates and ettringite, as well as other crystalline phases, leads to a decrease in the compressive strength of the cement stone. During 6 months of microbiological corrosion of cement concrete under conditions of constant wetting, the compressive strength decreases by about 35 %.

Effect of Cement Paste Preparation Procedure and Cement Stone Age on its Phase Composition

2021 ◽  
Vol 887 ◽  
pp. 473-479
Author(s):  
I.N. Maksimova ◽  
N.I. Makridin ◽  
Anna V. Dergunova ◽  
Yu.V. Babenkova
Keyword(s):  
Phase Composition ◽  
Cement Paste ◽  
Cement Stone ◽  
Building Structures ◽  
Analysis Method ◽  
Optimal Sequence ◽  
Concrete Mixtures ◽  
Concrete Building ◽  
The Given ◽  
Mixing Water

Self-levelling and self-consolidating concrete mixtures formed with the use of superplasticizers are worthwhile for the manufacture of reinforced concrete structures. It is important to evenly distribute not only the mixing water in the system, but also the dissociated plasticizer ions for cement dispersed compositions with plasticizing additives. It is established that the optimal sequence of loading and mixing of the components of a cement composition is not only a promising direction for intensifying the manufacture of concrete building structures, but also a tool for improving the mechanical properties of cement brick and concrete made on its basis, as well as for increasing its durability and reliability. When superplasticizers are introduced into the pre-ground cement paste, the rheological properties of the compositions are improved, as well as the structure of the hardened composites. The given article is devoted to the study of the effect of the procedural factor and the duration of mixing of highly concentrated cement compositions with the addition of a superplasticizer based on naphthalene sulfonic acid (SP C-3) on the phase composition of hardened composites during various periods of hydration. Experimental results were obtained using the X-ray phase analysis method. Tested are 15 series of samples of cement stone with W/C ratio range between 0,18 and 0,27 and SP C-3 between 0 and 1.0 % by cement weight. Comparing the phase composition of cement stone after 28 days of hardening with that of 4,5 years, it was found that at first the C3SH2 phase, particularly enriched with calcium oxide, is formed, which decays over time and disappears in the 4,5-year hardening amples.

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