Solid content test of chemical admixture

Dry Material (Solid) Content Test of Chemical Admixtures

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Solid Content Test of Admixture

Chemical admixtures have become an essential component of modern concrete, particularly when high workability is required without increasing the water content. Depending on the product, admixtures are supplied either as liquids or as powders. Solid content of admixture impacts its properties. Measuirng solid content helps in following ways.

  • Verifies the quality and consistency of the admixture supplied by the manufacturer.
  • Helps achieve uniform concrete performance across different batches.
  • Prevents variations in workability, setting time, and compressive strength caused by incorrect admixture dosing.

Test Summary

This test determines the percentage of dry solids present in a chemical admixture. A measured quantity of the admixture is mixed with oven-dried sand inside a wide-mouth glass bottle and heated in an electric oven under controlled conditions. After drying, the remaining solid residue is measured by weighing the bottle before and after the test.

Reference: IS 9103:2018

Apparatus Required

  • Wide-mouth glass bottle (approximately 60 mm in diameter and 30 mm in height) fitted with a glass stopper
  • Desiccator
  • Pipette
  • Electric drying oven
  • Electronic weighing balance with an accuracy of 0.001 g

Test Procedure

Step 1

Take a clean wide-mouth glass bottle and place approximately 25 to 30 g of completely dry sand inside it. Fit the bottle with its glass stopper and keep it in an electric oven maintained at 105 ± 2°C for 17 ± ¼ hours. If the sand has already been dried previously, the drying period may be shortened accordingly.

Step 2

After drying, continue heating until the bottle and sand attain a constant mass. Remove the bottle from the oven, immediately transfer it to a desiccator, and allow it to cool to room temperature. Weigh the bottle, sand, and stopper together to the nearest 0.001 g, and record the reading.

Step 3

Remove the stopper and use a pipette to carefully add 4 mL of the liquid chemical admixture onto the dry sand. Ensure that the admixture is spread uniformly over the entire sand surface.

Step 4

Replace the stopper securely and place the bottle back into the electric oven. Dry the sample at 105 ± 2°C for 17 ± ¼ hours.

Step 5

After the drying period is complete, remove the bottle from the oven and place it inside a desiccator until it cools to room temperature. Weigh the bottle along with the dried sample and stopper to the nearest 0.001 g.

Step 6

Return the bottle with the stopper to the oven and continue drying for an additional one hour. Remove, cool in the desiccator, and weigh again. Repeat this drying and weighing cycle until two consecutive measurements show no significant change, indicating that a constant mass has been achieved.

Step 7

For non-liquid (powder) admixtures, place approximately 3 g of the sample directly into the glass bottle. Close the bottle with the stopper and dry it in the electric oven at 105 ± 2°C for 17 ± ¼ hours. Thereafter, follow the same cooling, weighing, and repeated drying procedure until a constant mass is obtained. Record all observations in the appropriate observation table.

Observations and Calculations

During the test, record the mass of the bottle assembly before adding the admixture and after the drying process. The difference between these measured values is used to determine the dry material (solid) content of the chemical admixture. All weight measurements should be recorded to an accuracy of 0.001 g.

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