Magical Mortar Mix

Magical Mortar Mix for Flagstone and Paving Brick:

"The hydrated lime you read about is a dry fluffy powder made by adding a very specific amount of water to regular lime and mixing the two in large mechanical mixing machines. The small amount of water activates the calcium oxide in the lime but does not turn it into a paste or putty. Mortars that contained traditional lime were often subject to popping, pitting or disintegration if they were not carefully proportioned and mixed. Hydrated lime takes the guesswork out of mixing mortar and as such is very user-friendly. You can purchase hydrated lime at full-service building supply business that sell cement, mortar, plaster and other basic building materials.

Hydrated lime is not a necessary mortar ingredient. You can make mortar with just Portland cement, sand and water. The mortar that I used to permanently attach my brick and stone to my patios did not contain any hydrated lime. But adding hydrated lime to the mortar mix can be beneficial. The plasticity or workability of the mix is better. When hydrated lime is added to the mix, the sand and the cement do not separate. The final mortar is also more waterproof. Shrinkage cracking can often be eliminated or minimized when hydrated lime is added to the mixture. Replacing 10 to 15% of the total volume of cement with hydrated lime usually produces optimum results. Keep in mind that the Portland cement is the glue that holds the flagstone and brick to the concrete patio. Years ago many recipes I looked at suggested a ratio of three parts sand to one part cement for cement mortars. I altered that recipe and always mixed my ingredients 3 parts sand to 1.5 parts cement. After surviving 25 years of brutal winter freezing temperatures, my patios look like they day they were finished. I am convinced that my recipe is one that will work for you as well. If you decide to use the hydrated lime, you can use this recipe for the mortar: 3 five gallon buckets of dry sand, 6.38 gallons of Portland cement and 1.12 gallons of hydrated lime. Blend these ingredients together well before adding any water to the mix. Add water slowly until you get a mixture that resembles regular bricklayers mortar. Only mix as much mortar as you can use in one or two hours. Do not add water to the mortar if it starts to get stiff.