I'm building an extension at the mo and have been reading books and bit's on the web about mortar mixs's's's. They all say different things with regards to the ratios of sand to cement. what is the right one to use? I'm adding in plasteciser.
I've just finished the brickwork on my extension, and found that a mix of 4:1 achieved the same colour as the existing mortar. You may find that if you make the mix too weak,(i.e. >5:1) the mortar can be raked out with your nails when dry, so try to go with the strongest mix possible, while still retaining the colour match to existing. Plasteciser does not have any effect on the mortar (ie strength etc..) It just makes the mortar more "buttery" so it is easier to work with when laying bricks.
the strength of the mix is dependent on the situation its used in. 1:3 is mainly used below ground whereas 1:6 is used for general bricklaying. Dont just go for the strongest one. The reason a weaker mix is used above ground is to allow for diffential movement with the mortar rather than the bricks cracking.
if you find you need a lighter coloured mix you can always use white cement then vary the shade of sand you need or even mortar pigments.But always gauge every mix you make so it can be reprodced for subsequent mixes
4:1 is the norm above ground, should be gauged, not by the shovel,or yoy will be closer to 8:1. And plasterciser does have an effect, read the packet for correct amount.