AS 1141.34:2018 pdf free.Methods for sampling and testing aggregates Method 34: Organic impurities other than sugar.
7 Reagents
All reagents shall be of analytical grade. The following reagents are required:
(a) Sodium hydroxide.
(b) Tannic acid.
(c) Ethanol.
(d) Distilled or deionized water.
8 Test portion
By coning and quartering or using sample dividers, take a test portion of approximately 100 g from a laboratory sample obtained in accordance with the procedures of AS 1141.3.1. The test portion shall be used in the condition in which it was received.
9 Solutions required
The following solutions are required:
(a) Sodium hydroxide solution — A solution of 30 g of sodium hydroxide in 970 mL of distilled or deionized water.
(b) Reference colour solution — Two grams of tannic acid shall be dissolved in 10 mL of ethanol (ethyl alcohol), and the solution diluted to 100 mL with distilled water, then 2.5 mL of the resultant solution shall be added to 97.5 mL of the 3 % sodium hydroxide solution. The mixture shall be shaken vigorously and then allowed to stand in subdued light for 1 h before use. The reference colour solution shall be used within 2 h of its preparation [see Clause 10(c)].
10 Test procedure
The test procedure shall be as follows:
(a) Pour about 50 mL of 3 % sodium hydroxide solution into a 250 mL measuring cylinder or similar calibrated clear vessel. Add the fine aggregate to the 125 mL mark and adjust the sodium hydroxide level to the 200 mL mark with more solution (after removal of bubbles by shaking).
(b) Vigorously shake the mixture for not less than 30 s, taking care to ensure that all the fine aggregates are thoroughly wetted by the sodium hydroxide solution and that any lumps are dispersed. After shaking, allow the mixture to stand for 24 h ± 15 mm.
(c) At the end of the 24 h standing period, place 100 mL of reference colour solution in a rectangular clear glass bottle, and transfer 100 mL of the supernatant liquid from the test to a similar bottle.
(d) Compare the colour of the test solution to the colour of the reference when both are viewed in similar light conditions and the light paths through the solutions to the viewer are of the same length and angle.AS 1141.34 pdf download.