Hi all,
At this website it says that the cementitious part of a stucco mix includes both the portland AND the lime:
"It is important to note that the term “cement” includes all cementitious materials, such as cement plus lime. So if 1 part cement is used with one-half part lime, that equals 1-1/2 parts cementitious materials, and that total is then multiplied by the sand number. For the finish coat, for instance, the range is 1-1/2 to 3 parts sand: 1-1/2 times 1-1/2 is 2-1/4 and 1-1/2 times 3 is 4-1/2. So if we have 1-1/2 total parts of cementitious materials, the sand parts would range from 2-1/4 to 4-1/2"
But, at this website, a finish coat stucco mix ratio is defined as having 1 part portland, 1 part lime, and 1.5 to 3 parts sand without any mention of the cementitious relationship between the portland and lime:
"Now the sand in the mixture is cut back so that the mud is creamy: 1 part portland cement; 1 part hydrated lime; and 1 1/2 to 3 parts sand. The key to putting on the top coat is that it must be kept moist to avoid cracking. In this process you can color the mixture but mix the dye with water and stir well first, then add it to the top coat bucket as you are stir it with the drill and wand. Wet the surface before applying the coat and then trowel on."
My question is: which one has it right?
Additional info:
Here's another link with detailed information on stucco application, and it seems to agree with the first paragraph quoted above. See page 16 of the document and note the table column heading labelled "Volume of aggregate per sum of cementitious materials"
At this website it says that the cementitious part of a stucco mix includes both the portland AND the lime:
"It is important to note that the term “cement” includes all cementitious materials, such as cement plus lime. So if 1 part cement is used with one-half part lime, that equals 1-1/2 parts cementitious materials, and that total is then multiplied by the sand number. For the finish coat, for instance, the range is 1-1/2 to 3 parts sand: 1-1/2 times 1-1/2 is 2-1/4 and 1-1/2 times 3 is 4-1/2. So if we have 1-1/2 total parts of cementitious materials, the sand parts would range from 2-1/4 to 4-1/2"
But, at this website, a finish coat stucco mix ratio is defined as having 1 part portland, 1 part lime, and 1.5 to 3 parts sand without any mention of the cementitious relationship between the portland and lime:
"Now the sand in the mixture is cut back so that the mud is creamy: 1 part portland cement; 1 part hydrated lime; and 1 1/2 to 3 parts sand. The key to putting on the top coat is that it must be kept moist to avoid cracking. In this process you can color the mixture but mix the dye with water and stir well first, then add it to the top coat bucket as you are stir it with the drill and wand. Wet the surface before applying the coat and then trowel on."
My question is: which one has it right?
Additional info:
Here's another link with detailed information on stucco application, and it seems to agree with the first paragraph quoted above. See page 16 of the document and note the table column heading labelled "Volume of aggregate per sum of cementitious materials"
