Reference Colours Glasses

The test is carried out particularly to detect whether natural sands used in concrete and mortar production contain plant-derived organic substances. Since the organic content may adversely affect the cement hydration process, the test result can directly determine the suitability of the material for concrete mixtures. This test is defined in TS EN 1744-1 and ASTM C40 standards. During the test, a fine aggregate sample is mixed with a 3% sodium hydroxide (NaOH) solution and allowed to stand for a specified period. The colour of the resulting solution is compared with the standard colours on the Reference Colour Scale. If the obtained colour is darker than the reference colour, the sample is considered to contain organic matter. The reference Colour Scale consists of stable colours prepared within durable plexiglass tubes. The colour scale includes 7 different colours.