Sulfate Resistance of Alkali Activated Cements

2016 ◽  
Vol 865 ◽  
pp. 95-106 ◽  
Author(s):  
Pavlo Kryvenko ◽  
Sergii Guzii ◽  
Oleksandr Kovalchuk ◽  
Volodymyr Kyrychok
Keyword(s):  
Corrosion Resistance ◽  
Fly Ash ◽  
Protective Coatings ◽  
Resistance Coefficient ◽  
Cement Stone ◽  
Concrete Durability ◽  
Sulfate Resistance ◽  
Repair Materials ◽  
High Sulfate ◽  
Alkali Activated

One of the most important questions of concrete durability is increasing of corrosion resistance of cement stone and materials on his basis. Perspective way of solving such problems is using of alkali activated binders.Two cement systems were investigated to obtain different materials for different application - geocement system for repair materials and protective coatings and fly ash alkali activated hybrid cement for corrosion resistant common cements and concretes.It was studied sulfate resistance of fly ash alkali activated cements after 3 years of storing in aggressive environments like 5 and 10 % solutions of sodium sulfate, 2 and 4 % solutions of magnesium sulfate and sea salt solution. It was shown that fly ash containing cements are characterized by high corrosion resistance (coefficient of corrosion resistance after 3 years of storing in aggressive environment is in the ranges 0.8...1.0) comparing with clinker cements (0.45...0.88). Shown, that high sulfate resistance of cements under study in time is caused by graduate structure development and crystallization of new formations with compacting structure of material that effect on service properties of materials.High corrosion resistance of geocement compositions (coefficient of corrosion resistance 0.9-1.05) in sulfate environment is possible because of formation of faujasite, chabasite, mordenite and nozean phases in the structure of materials. Optimal composition of geocement compositions were developed according mathematical planning of experiments and tested.

Research on Sulfate Attack Resistance of Concrete with Sulfate Corrosion-Resistance Admixture

2011 ◽  
Vol 71-78 ◽  
pp. 3562-3565
Author(s):  
Ben Ju Yang ◽  
Qiu Yi Li ◽  
Song Gao ◽  
Tao Li
Keyword(s):  
Corrosion Resistance ◽  
Fly Ash ◽  
Resistance Coefficient ◽  
Sulfate Attack ◽  
Sulfate Resistance ◽  
Fly Ash Concrete ◽  
Slag Powder ◽  
Performance Requirements ◽  
Invention Patent

A concrete sulfate corrosion-resistance admixture is developed with anhydrous calcium sulfo aluminate (C-S-A), super fine slag powder (P800) and anhydrite (CaSO4) in this paper. Scope of prescription is optimized according to performance requirements of JC/T1011-2006. This sulfate corrosion-resistance admixture has declared Chinese national invention patent (201010256189.2)[1]. Corrosion resistance coefficient is tested after sulfate corrosion-resistance admixture is adjoined into fly ash concrete. The results reveal that sulfate resistance of the concrete is obviously improved by addition of sulfate corrosion-resistance admixture, and the its anti sulfate erosion grade is KS150.

Sulfate Resistance of Concrete under Restrained Condition

2011 ◽  
Vol 280 ◽  
pp. 67-70
Author(s):  
Zhong Hua Li ◽  
Shu Rong Feng ◽  
Chao Su
Keyword(s):  
Corrosion Resistance ◽  
Fly Ash ◽  
Concrete Cracking ◽  
Surface Cracking ◽  
Sulfate Resistance ◽  
Restrained Condition ◽  
Drying And Wetting Cycles

Cracking due to shrinkage and restraint can accelerate corrosion of concrete resulted from harmful environment. Sulfate resistance of concrete under restrained condition was researched during drying and wetting cycles. The results showed that restraint can lead to controlled concrete cracking as result of shrinkage. It decreased sulfate corrosion resistance of concrete compared with free concrete. Due to 30% slag and 20% fly ash was added, surface cracking was avoided but scaling mass still higher than free concrete after drying and wetting cycles.

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.

scholarly journals RILEM TC 247-DTA round robin test: sulfate resistance, alkali-silica reaction and freeze–thaw resistance of alkali-activated concretes

2020 ◽  
Vol 53 (6) ◽  
Author(s):  
Frank Winnefeld ◽  
Gregor J. G. Gluth ◽  
Susan A. Bernal ◽  
Maria C. Bignozzi ◽  
Lorenza Carabba ◽  
...  
Keyword(s):  
Fly Ash ◽  
Round Robin ◽  
High Reactivity ◽  
Rilem Technical Committee ◽  
Alkali Silica Reaction ◽  
Experimental Conditions ◽  
Freeze Thaw ◽  
Sulfate Resistance ◽  
Durability Testing ◽  
Alkali Activated

AbstractThe RILEM technical committee TC 247-DTA ‘Durability Testing of Alkali-Activated Materials’ conducted a round robin testing programme to determine the validity of various durability testing methods, originally developed for Portland cement based-concretes, for the assessment of the durability of alkali-activated concretes. The outcomes of the round robin tests evaluating sulfate resistance, alkali-silica reaction (ASR) and freeze–thaw resistance are presented in this contribution. Five different alkali-activated concretes, based on ground granulated blast furnace slag, fly ash, or metakaolin were investigated. The extent of sulfate damage to concretes based on slag or fly ash seems to be limited when exposed to an Na2SO4 solution. The mixture based on metakaolin showed an excessive, very early expansion, followed by a dimensionally stable period, which cannot be explained at present. In the slag-based concretes, MgSO4 caused more expansion and visual damage than Na2SO4; however, the expansion limits defined in the respective standards were not exceeded. Both the ASTM C1293 and RILEM AAR-3.1 test methods for the determination of ASR expansion appear to give essentially reliable identification of expansion caused by highly reactive aggregates. Alkali-activated materials in combination with an unreactive or potentially expansive aggregate were in no case seen to cause larger expansions; only the aggregates of known very high reactivity were seen to be problematic. The results of freeze–thaw testing (with/without deicing salts) of alkali-activated concretes suggest an important influence of the curing conditions and experimental conditions on the test outcomes, which need to be understood before the tests can be reliably applied and interpreted.

Study on Corrosion Resistance Coefficient Assessment Method for Sulfate Resistance of Cementitious Material

2012 ◽  
Vol 174-177 ◽  
pp. 624-630
Author(s):  
Kun Peng Gu ◽  
Cheng Qi Wang
Keyword(s):  
Corrosion Resistance ◽  
Portland Cement ◽  
Resistance Coefficient ◽  
Assessment Method ◽  
Cementitious Material ◽  
Mineral Admixture ◽  
Corrosion Mechanism ◽  
Experimental Conditions ◽  
Sulfate Resistance ◽  
Coefficient Method

By means of testing corrosion resistance coefficient of different cementitious material under the sulfate corrosion experimental conditions, sulfate resistance of cementitious material and assessment method are studied. The results show that 90d is proper corroded age for assessment sulfate resistance of cementitious material by corrosion resistance coefficient method, and the assessment method is put forwarded. Sulfate resistance of cementitious material can be divided into five classes according to corrosion resistance coefficient assessment method as follows: “very low”, “low”, “moderate”, “high” and “very high”. The sulfate resistance of Portland cement is better than ordinary Portland cement, and both of them are low. Mineral admixture with proper content can improve sulfate resistance of cementitious materia largely, but do not always available to all content. Sulfate corrosion mechanism of different kinds of cementitious material is analyzed.

scholarly journals Steel Corrosion Behavior in Light Weight Fly-Ash Based Alkali Activated Mortars

2021 ◽  
Vol 11 (4) ◽  
pp. 1908
Author(s):  
Giulia Masi
Keyword(s):  
Corrosion Resistance ◽  
Fly Ash ◽  
Pore Solution ◽  
Tap Water ◽  
Steel Corrosion ◽  
Steel Structures ◽  
Solution Chemistry ◽  
Light Weight ◽  
Steel Corrosion Resistance ◽  
Alkali Activated

Alkali activated materials as possible sustainable alternative to cementitious binders showed competitive performances in terms of mechanical and durability properties and high temperature stability. For this reason, light weight fly-ash based mortars have already been optimized as passive fire protective coating for steel structures. However, a lack of information about the durability of these innovative systems in terms of steel corrosion resistance is still present. Thus, this study aims at investigating the durability of steel coated with a 20-mm thick light weight mortar layer in a neutral environment (tap water) and in presence of chloride-containing solution (0.2 M NaCl). In addition, the influence of pore solution chemistry and pH was discussed through electrochemical testing in leachate pore solution and NaOH aqueous solutions at different concentrations. It was found that almost complete protection ability of light weight mortar was obtained when coated steel is exposed to neutral solution for 60 days, while in presence of chlorides, steel is more susceptible to corrosion already after 40 days of exposure. In addition, the developed open porosity of the light weight mortars, it was found that pH and the chemistry of the pore solution in contact with steel strongly influenced the steel corrosion resistance.

Mechanical Performances and Corrosion Resistance of Reinforced Fly Ash Geopolymer Mortars

2014 ◽  
Vol 92 ◽  
pp. 50-55 ◽  
Author(s):  
Maria Elia Natali ◽  
Stefania Manzi ◽  
Lorenza Carabba ◽  
Cristina Chiavari ◽  
Maria Chiara Bignozzi ◽  
...  
Keyword(s):  
Corrosion Resistance ◽  
Fly Ash ◽  
Corrosion Behaviour ◽  
Waste Recycling ◽  
Molar Ratio ◽  
Molar Ratios ◽  
Mechanical Performances ◽  
Mechanical And Microstructural Properties ◽  
Alkali Activated Binders ◽  
Alkali Activated

The growing focus on issues related to the control of CO2 emissions, energy conservation and waste recycling pushes the construction industry to tackle the challenge of sustainable development. The production of ordinary Portland cement (OPC), main product of the sector, is one of the most polluting in terms of CO2 emissions, thus finding alternative binder is becoming an urgent matter. Geopolymers are largely investigated for this purpose, but studies concerning the durability of reinforced conglomerates prepared with alkali activated binders are only few. The present work aims at investigating the durability performances of steel reinforced geopolymer mortar samples based on carbon fly ash in comparison with OPC mortar. The effect of different Na2O/SiO2 molar ratios in the geopolymer mixes is evaluated in terms of mechanical and microstructural properties as well as corrosion resistance in a chloride rich environment. The obtained results show that under the same severe environmental conditions more limited chloride amounts penetrate in reinforced fly-ash geopolymers where a better corrosion behaviour is also detected up to a week of exposure for samples with a nominal Na2O/SiO2 molar ratio equal to 0.12 and 0.14. Instead, the corrosion resistance is quite similar to that of reinforced OPC mortar when a period of three months is considered.

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