correlation between chemical composition and alkali attack
Alkali–silica reactionWikipedia
Anhydrous and hydrated silica surface with siloxane and silanol groups along with surface bound water molecules. The surface of solid silica in contact with water is covered by siloxane bonds (≡Si–O–Si≡) and silanol groups (≡Si–OH) sensitive to an alkaline attack by OH−
Get Price
USAInhibitors for alkali-glass reactions in
A glass reinforced cement composition containing a scavenger material as an inhibitor to prevent or greatly reduce attack and degradation of the glass reinforcement by the alkali content of the inorganic alkaline cement binder. The scavenger is a finely divided alkali-reactive material which contains silica as the major constituent thereof and which has a reactivity with the alkali content of
Get Price
Influence of composition and structure on the thermal
Experimental data from literature on the thermal quenching of the Eu 2 5d–4f emission in the M x Si y N z (M = alkali alkaline earth or rare earth) nitridosilicates have been collected and evaluated. No clear correlation was observed between the activation energy for thermal quenching and the Stokes shift suggesting that non-radiative relaxation via a thermally excited cross-over from the
Get Price
COMPRESSIVE STRENGTH AND DURABILITY OF CEMENT
The resistance of concrete to chemical attack has improved with increase relationship between Ca (OH) 2 content and gypsum formation. Ettringite formation laboratory and contained in their composition alkali wastes of oil and cellulose paper industries (type SM-S CM-B SM-O).
Get Price
(PDF) Correlation of Reaction Products and Expansion
Malvar and Lenke24 among which the latter showed the However there was no clear correlation reported between strong positive effects of SiO2 and Al2O3 as well as the negative the exact chemical composition of the gels and their swelling effect of CaO in ASR expansion. nature.
Get Price
(PDF) Mechanism of damage for the alkali–silica reaction
IntroductionThe chemical reaction between certain forms of silica present in aggregates and the alkali hydroxides and the portlandite of the hydrated cement paste better known as the alkali -silica reaction (ASR) may cause damage in concrete structures.ASR has been widely studied and its mechanisms have been described using different models 1 -3 .
Get Price
ASTM InternationalJournal of Cement Concrete and
Evaluation of the Potential of Densified Silica Fume to Cause Alkali-Silica Reaction in Cementitious Matrices Using a Modified ASTM C 1260 Test Procedure. Chemical and Petrographic Analyses and ASTM Test Procedures for the Study of Delayed Ettringite Formation. Development of Performance Tests for Sulfate Attack on Cementitious Systems
Get Price
Glass Viscosity Calculation
The prediction confidence interval largely depends on the glass composition of interest the composition uncertainty and the viscosity level. The mixed-alkali effect for the viscosity is shown to be caused mainly not by alkali-alkali but by non-linear alkali-silica interactions. Download viscosity calculator including correlation matrices 1.7
Get Price
Sulfate attack of cement matrix containing inorganic
This paper presents an experimental study on the durability of mortar specimens incorporating inorganic alkali-free accelerator (AFA) exposed to external sulfate attack. Visual examination compressive strength expansion and density of mortar specimens with or without AFA were monitored up to 360 days of exposure. Additionally in order to identify the products formed by sulfate attack
Get Price
Correlation between chemical composition and alkali attack
Nov 01 2017 · To further understand the relation between chemical composition and alkali attack resistance the microstructure photographs of all specimens at their edge after alkali exposure are shown in Fig. 7. Chemical reactions phenomena due to the attack of alkali vapor was clearly observed in reference specimen.
Get Price
Composition Decomposition and Combustion Reactions
A combustion reaction occurs when a reactant combines with oxygen many times from the atmosphere to produce oxides of all other elements as products any nitrogen in the reactant is converted to elemental nitrogen N 2.Many reactants called fuels contain mostly carbon and hydrogen atoms reacting with oxygen to produce CO 2 and H 2 O. For example the balanced chemical equation for the
Get PriceSulfate attack of cement matrix containing inorganic
This paper presents an experimental study on the durability of mortar specimens incorporating inorganic alkali-free accelerator (AFA) exposed to external sulfate attack. Visual examination compressive strength expansion and density of mortar specimens with or without AFA were monitored up to 360 days of exposure. Additionally in order to identify the products formed by sulfate attack
Get Price
Physical and Chemical Relationships in Accelerated
Feb 23 2021 · Alkali-activated cements prepared from aluminosilicate powders such as blast furnace slag and fly ash are rapidly attracting attention as alternatives to cement because they can significantly reduce CO 2 emissions compared to conventional cement concrete. In this study we investigated the relationship between the physical and chemical changes by accelerated carbonation conditions of alkali
Get Price
National Cooperative Highway Research Program RESULTS
The analysis showed a very high negative correlation of sulfate attack with C 4 AF and Fe 2 O 3. Also a strong correla-tion was noted between C 3 A/C 4 AF ratio and 6-month expansion. A much weaker correlation was observed for both total equivalent alkali and alumina contents. Cracking Tendency A correlation between the chemical and physical char-
Get Price
Glass Viscosity Calculation
The prediction confidence interval largely depends on the glass composition of interest the composition uncertainty and the viscosity level. The mixed-alkali effect for the viscosity is shown to be caused mainly not by alkali-alkali but by non-linear alkali-silica interactions. Download viscosity calculator including correlation matrices 1.7
Get Price
Introductory Chapter Properties and Applications of
Jan 11 2018 · The chemical interaction and mechanical interlocking between the hydraulic binder and the additives. Effect of hydraulic binder composition that is calcium alumina sulfate alkali and silica ration. Effect of curing temperature as it increases ultimate strength is reduced.
Get Price(PDF) Mechanism of damage for the alkali–silica reaction
IntroductionThe chemical reaction between certain forms of silica present in aggregates and the alkali hydroxides and the portlandite of the hydrated cement paste better known as the alkali -silica reaction (ASR) may cause damage in concrete structures.ASR has been widely studied and its mechanisms have been described using different models 1 -3 .
Get Price
ASTM InternationalJournal of Cement Concrete and
Evaluation of the Potential of Densified Silica Fume to Cause Alkali-Silica Reaction in Cementitious Matrices Using a Modified ASTM C 1260 Test Procedure. Chemical and Petrographic Analyses and ASTM Test Procedures for the Study of Delayed Ettringite Formation. Development of Performance Tests for Sulfate Attack on Cementitious Systems
Get Price
Composition–solubility–structure relationships in calcium
The interplay between the solubility structure and chemical composition of calcium (alkali) aluminosilicate hydrate (C-(N K-)A-S-H) equilibrated at 50 °C is investigated in this paper. The tobermorite-like C-(N K-)A-S-H products are more crystalline in the presence of alkalis and generally have larger basa
Get Price
Effects of Sodium Ions on Synthesized Alkali Silica
The alkali-silica reaction (ASR) leading to serious structural degradation is the chemical reaction between reactive silica presenting in aggregates and hydroxyl ions from cement paste or pore solution. Although the chemical mechanism of ASR attack has been well studied for years the mechanism of micro scale ASR gel
Get Price
Composition–solubility–structure relationships in calcium
The interplay between the solubility structure and chemical composition of calcium (alkali) aluminosilicate hydrate (C-(N K-)A-S-H) equilibrated at 50 °C is investigated in this paper. The tobermorite-like C-(N K-)A-S-H products are more crystalline in the presence of alkalis and generally have larger basa
Get Price
National Cooperative Highway Research Program RESULTS
The analysis showed a very high negative correlation of sulfate attack with C 4 AF and Fe 2 O 3. Also a strong correla-tion was noted between C 3 A/C 4 AF ratio and 6-month expansion. A much weaker correlation was observed for both total equivalent alkali and alumina contents. Cracking Tendency A correlation between the chemical and physical char-
Get PriceThe Durability of Alkali-Activated Materials in Comparison
Alkali-activated materials (AAMs) also known as geopolymers are manufactured by chemical reactions between an alkaline activator and reactive aluminosilicate materials 2–4 . The reaction process polymerization mechanism and products of AAMs have been extensively studied 5–19 .
Get PriceRelationship between Phase Occurrence Chemical
May 22 2019 · A preferential corrosion attack of εn was found while the binary δ phase (Al3Pd2) remained free of corrosion. A de-alloying of Al from εn and formation of intermittent interpenetrating channel networks occurred in both alloys. The corrosion behavior of εn is discussed in terms of its chemical composition and crystal structure.
Get Price
DurabilityPortland Cement Association
Durability is the ability to last a long time without significant deterioration. A durable material helps the environment by conserving resources and reducing wastes and the environmental impacts of repair and replacement. The production of replacement building materials depletes natural resources and can produce air and water pollution.
Get Price
Structural Characterization of Lignin and Its Degradation
Lignin is highly branched phenolic polymer and accounts 15–30 by weight of lignocellulosic biomass (LCBM). The acceptable molecular structure of lignin is composed with three main constituents linked by different linkages. However the structure of lignin varies significantly according to the type of LCBM and the composition of lignin strongly depends on the degradation process.
Get Price
Effects of Sodium Ions on Synthesized Alkali Silica
The alkali-silica reaction (ASR) leading to serious structural degradation is the chemical reaction between reactive silica presenting in aggregates and hydroxyl ions from cement paste or pore solution. Although the chemical mechanism of ASR attack has been well studied for years the mechanism of micro scale ASR gel
Get Price
Cement ChemistryThe Concrete Portal
Composition of pore solution. The evolution of pore solution composition for a typical cement (0.6 equivalent Na 2 O 3 SO 3 0.5 w/c) is shown in Figure 3. By 1 week the only ions remaining in appreciable concentration are Na K and OH-.
Get PriceCOMPRESSIVE STRENGTH AND DURABILITY OF CEMENT
The resistance of concrete to chemical attack has improved with increase relationship between Ca (OH) 2 content and gypsum formation. Ettringite formation laboratory and contained in their composition alkali wastes of oil and cellulose paper industries (type SM-S CM-B SM-O).
Get Price
