Water content for mortar

[Ingenuir]

Hi everybody,

I am trying to mix cement:lime:sand mortar in the lab for research purpose. However, I am not sure about the amount of water required to achieve good strength and sufficient workability for cement:lime:sand mortar. For cement:sand mortar, the water/cement ratio is normally being 0.45-0.65 or so. Will the water/cement ratio change when we add lime? should we proportion water for the combined cement+lime content.

I am mixing a 1:2:9 cement:lime:sand mortar and have worked out the following material weights in accordance with ASTM C270-06.

Portland cement: 131 grams (density = 94 lbs/ft3) Hydrated lime: 111 grams (density = 40 lbs/ft3) Sand: 1000 grams (density = 80 lbs/ft3)

Can you please comment on the mix design. Obviously, it is quite a weak mortar mix - ASTM type 'O'.

If we work out the amount of water with a 0.485 (ASTM standard) w/c ratio, the amount of water comes out to:

water = 0.485 (131) = 64 grams

or with a water/lime + cement ratio of 0.485:

water = 117 grams

I thank you in anticipation of your promt response.

With best regards,

Hamid

[tbasc]

Check Brick Industry Association (BIA) web site. The Tech Notes section has good info. TB

[Glenn]

Or make it simple, ie the kiss method. Keep adding water out of a measured container until you get a 2" or your choice of slump, see how much water you used and use that proportion for the larger mix. Why make it so complicated?

[tmurf.1]

cement lime and sand are normally measured in cubic units as opposed to weight. The water should be added untill you have the stiffist workable consistantsy. The most common ratio for cement, lime and sand is 1:1:6. You should mix the dry ingrediants first then add water slowly while mixing.