Posted: Tue Aug 01, 2006 1:35 pm
Hi All,
We are finally at the stage of pointing Indian stone and Granit sets patio and here are three questions:
1. Building Sand (soft sand) or Sharp Sand?
The first couple of wheelbarrows were mixed using 3 parts of building sand and one part of cement, as suggested on this site. I was then recommended to use sharp sand instead of building sand, because I was told, it will be stiffer once set and easier to work with. Now I have a dilemma, since I am mixing a colour additive it will be difficult to match the colour if I was to switch to sharp sand but on the other hand if the mix is not going to be stiff enough I will have to re-point very soon? Shall I stick with my building sand mixture?
2. PVA as an additive for pointing mix.
I was recommended to use PVA in the pointing mix, however when technical support of the PVA product I got from B&Q, was told that it should not be used for External Purposes, since it becomes liquid as soon as it has contact with water. They also told me that there are some builders who use PVA in a way it was not designed for and it works for some. Does anyone know if PVA has any benefits / drawbacks? What other products would you recommend to make the pointing mix flexible/stiff so it does not crack?
3. Use of colour for partial mix.
The pointing mix is done is a wheelbarrow: full bag of building sand + cup of powdery colouring agent + third of a cement bag + water… The weather is a bit unpredictable at the moment and mixing one wheelbarrow of pointing mix might mean that I will have to throw away some because I can’t point any further since it is raining… I was wondering if I could do with mixing smaller loads - say a bucket that will keep me going for a couple of hours and when it rains I can cover the pointed area with a plastic sheet etc.
The problem is that I was mixing in a wheelbarrow and my colouring agent measure is done using a cup, I wouldn’t like to guess the amount of colouring agent ratio to be mixed in a bucket. I was wondering if it would be possible to do a partial mix of sand and colouring agent, leave it in the wheelbarrow (for several days?) and three parts of that mixture can be taken and mixed with one part of cement for the small amount of a pointing mix. Does anyone know if it is safe to leave the sand/colouring agent mix for a while or will there be any reaction between the two?
Thank you in advance
Alex
We are finally at the stage of pointing Indian stone and Granit sets patio and here are three questions:
1. Building Sand (soft sand) or Sharp Sand?
The first couple of wheelbarrows were mixed using 3 parts of building sand and one part of cement, as suggested on this site. I was then recommended to use sharp sand instead of building sand, because I was told, it will be stiffer once set and easier to work with. Now I have a dilemma, since I am mixing a colour additive it will be difficult to match the colour if I was to switch to sharp sand but on the other hand if the mix is not going to be stiff enough I will have to re-point very soon? Shall I stick with my building sand mixture?
2. PVA as an additive for pointing mix.
I was recommended to use PVA in the pointing mix, however when technical support of the PVA product I got from B&Q, was told that it should not be used for External Purposes, since it becomes liquid as soon as it has contact with water. They also told me that there are some builders who use PVA in a way it was not designed for and it works for some. Does anyone know if PVA has any benefits / drawbacks? What other products would you recommend to make the pointing mix flexible/stiff so it does not crack?
3. Use of colour for partial mix.
The pointing mix is done is a wheelbarrow: full bag of building sand + cup of powdery colouring agent + third of a cement bag + water… The weather is a bit unpredictable at the moment and mixing one wheelbarrow of pointing mix might mean that I will have to throw away some because I can’t point any further since it is raining… I was wondering if I could do with mixing smaller loads - say a bucket that will keep me going for a couple of hours and when it rains I can cover the pointed area with a plastic sheet etc.
The problem is that I was mixing in a wheelbarrow and my colouring agent measure is done using a cup, I wouldn’t like to guess the amount of colouring agent ratio to be mixed in a bucket. I was wondering if it would be possible to do a partial mix of sand and colouring agent, leave it in the wheelbarrow (for several days?) and three parts of that mixture can be taken and mixed with one part of cement for the small amount of a pointing mix. Does anyone know if it is safe to leave the sand/colouring agent mix for a while or will there be any reaction between the two?
Thank you in advance
Alex