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Admixtures Testing

One of the major aspects of cement chemistry that concern concrete suppliers and users is the influence of chemical admixtures on concrete. A wide variety of chemical admixtures have been introduced to the concrete industry over the last three decades, and engineers are increasingly concerned about the impacts of these admixtures on cement and concrete performance.

Many researches dealing with admixtures have been conducted and have showed the various effects of admixtures on concrete. For example, air-entraining admixtures are widely used where concrete will be subject to repeated freeze-thaw cycles. Air-entraining agents have no considerable effect on the rate of hydration of cement or on the chemical composition of hydration products. However, an increase in cement fineness or a decrease in cement alkali content generally increases the amount of an admixture required for a given air content. Water reducers or retarders interferes with cement compounds and affect their hydration. For example, Lignosulfonate-based admixtures affect the hydration of C3A, which controls the setting and early hydration of cement. C3S and C4AF hydration is also affected by water reducers.

Researches also showed that the cement alkali and C3A contents are among the basic compounds affected by the admixtures and must be analyzed to achieve the desired mix. Also, retarders are more effective with cement of low alkali and low C3A content, and water reducers seem to improve the compressive strength of concrete containing cements of low alkali content more than that of the concrete containing cements of high alkali content.

TQP can serve you identifying your admixture, studying its effect on concrete and analyzing its physical and chemical properties to check its compliance with the set Materials Safety data sheet.


Admixture Tests

Admixtures Test Method Description Date
Calcium Nitrite content of admixture Vogel Calcium nitrite is one of the common types of corrosion inhibiting admixtures. Corrosion inhibiting admixtures increase the passivation state of reinforcement in concrete structures. This can inhibit the corrosion process over extended periods when passivation provided by the alkali of the cement is lost as a result of chloride ingress or carbonation. Jan. 2017
Chloride content of admixture BS EN 480-10 Chloride, the non-desired ion in admixture, and accordingly in concrete, could be determined potentiometrically. Water-soluble chlorides, in combination with oxygen and moisture, can cause corrosion of embedded metals in concrete. Admixtures having % of chloride higher than the specified values shall be rejected. (usually <1000ppm as per BS 480-10, or not above manufacturer stated value) Jan. 2017
Density of foaming agent Pycnometer Foaming Agents used in making preformed foam for cellular concrete shall satisfy the requirements stated in ASTM C869 Jan. 2017
Foam concrete mix design-in situ ASTM C260, ACI 211.1 Foaming Agents used in making preformed foam for cellular concrete shall satisfy the requirements stated in ASTM C869 Jan. 2017
pH of admixture ASTM-E70 Electrometric measurement of pH values of admixtures with the glass electrode is one of the main process control variables in the admixture industry. pH of concrete admixture is almost alkaline; its acidic value could be an indication of its rancidity or expiry. Jan. 2017
pH of foaming agent ASTM E70 Foaming Agents used in making preformed foam for cellular concrete shall satisfy the requirements stated in ASTM C869 Feb. 2017
pH, specific gravity and solids content of admixture ASTM C494 These are the routine analyses of admixtures usually conducted to control its quality. However, the practical way to evaluate the effectiveness of admixtures is to make trial mixes and check its impact on the Rheology of the concrete, its setting time and strength performance over time. Feb. 2017
Residue by Oven Drying of foaming agent ASTM C 233 Foaming Agents used in making preformed foam for cellular concrete shall satisfy the requirements stated in ASTM C869 Feb. 2017
Sodium Gluconate content in admixture TQP Sodium Gluconate is commonly used as ingredient in superplasticizers and it is usually tested for its purity and content in admixture. Feb. 2017
Soluble chloride content of foaming agent BS 5075 p1 Foaming Agents used in making preformed foam for cellular concrete shall satisfy the requirements stated in ASTM C869 March 2017
Sulfate content of admixture TQP Sulfate is commonly available in admixture at remarkable percentages (usually 5 to 20%) the determination of its concentration reflect the quality of the raw materials of the admixture. Sulfate is tested gravimetrically. March 2017

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  • Home
  • Testing
    • Admixtures
    • Water
    • Aggregates
    • Soil
    • Concrete
    • Cement
    • Bitumen
    • Coatings
    • Tiles
    • Plastics
    • Training
    • Various
  • Consultancy
  • About Us
  • Contact Us