The correct mixing sequence and homogenity of mix is important if consistent, repeatable test results are to be obtained. Mixers should be powerful enough to ensure that the motor’s speed is not affected by the mix constituents and designed to ensure that the mixer action and blade does not break down individual sand particles and preferably provide automatic mixing cycles.
In the USA, ASTM C109 and C190 are the definitive methods for determining compressive and tensile strength. The BS 4550 method using either 70.7 mm or 100 mm cubes has been retained in the UK only for comparative purposes. EN196-1 is now the definitive
method.
