AS 1141.34 pdf download

AS 1141.34 pdf download.Methods for sampling and testing aggregates
2  Principle
The test relies on the reaction of humus material with a sodium hydroxide solution to produce a dark colour in the liquid the intensity of which is approximately proportionate with the mass content of humus in the fine aggregate. Based on 1917 research, fine aggregate with humus contents that have a resultant solution colour lighter than, or equal to, the Standard colour are expected to have no detrimental effects when used in concrete or mortar products. A darker coloured solution may be the result of humus content and/or reactions from other contaminents and may require further investigation to determine the extent of possible effects to concrete or mortar properties.
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 min. (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. Or, as an alternative to Item (d), either: (i) Compare the colour of the supernatant liquid, viewed through the thickness of the glass bottle with the colour of a standardized glass sheet. (i) Compare the colour of the supernatant liquid, viewed through the thickness of the glass bottle with the colour of a standardized glass sheet. In this case the standardized glass plate shall be compared to the reference solution in a bottle with a light path that allows the viewed colour of the solution to match the colour of the glass plate. Once this is determined, the test solution shall be contained in a bottle with the same length light path; or 2 AS 1141.34:2018 © Standards Australia Limited 2018 (ii) Test the supernatant liquid in a colour comparator designed specifically for this test. In either of these alternatives, the medium used for the standardized colour shall be compared with the tannic acid colour solution on an annual basis and the currency of this comparison shall be verified before each test. NOTE  European Standard EN 1744‑1:2009 provides details of suitable standardized plates and colour comparators.