Mortar pointing probem ?

[remus]

Hi
After what seems a lifetime, well about 12 months, building walls filling the area with 12�- 20� of hardcore installing drains etc. I have finally started to lay the patio.
I am using Marshall Saxon 450 *450 buff slabs on a 10 to 1 semi dry mix. With a fall of 1 in 60
I have so far laid about 90sqm and have pointed part of this, using 4 to 1 wet mix.
This was done across two dry days. The problem is after it has rained the slabs, which have not been pointed, dry out within a few minutes. But where the pointed slabs are the mortar seems to soak up the water which then soaks into the slab picture framing it.
The first area I pointed does dry out after some sun. But the second days pointing area, which is next to the first takes a good few days before the slabs dry out. The mix was the same each day. The joints have hardened but they seem to suck up the rainwater.
Not having had a patio before is this only to be expected.
Just want to check if there is a problem before I waste any more time pointing.



Regards Kevin.

[lutonlagerlout]

this is bound to happen to some extent mate,on the unpointed slabs the mortar runs between the joints,whereas on the pointed ones the mortar is partially permeable
BTW what mortar mix did you use?
at least theres no puddles
cheers tony
a picture would be handy as well

[remus]

Thanks for the reply Tony.
We have just had one of those rare days in Kent. It has rained more on than off all day ! So the photo will have to wait for the slabs to dry a little.
The mortar mix was 1 bucket of BC Mastercrete to 4 buckets of soft sand. mixed in a mixer with a little water added. It was then placed in the joints following instructions on http://www.pavingexpert.com/point04.htm.
I think I may have found then answer ? I did say that the mortar had hardened but today in between the showers I tried the screwdriver test and found that on the second area of pointing I could with a bit of pressure push the screwdriver down to the subbase.
The pointing was done in the morning and we did have some rain over night. Do you think that the rain would have washed the cement out after that time.

Kevin.

[lutonlagerlout]

i dont know why but i prefer knocking up pointing mix by hand with a shovel and spot board
the mixer makes it to runny for me
seems very odd but i wouldnt push a screwdriver into any mortar for at least 72 hours,it takes a while to go really hard
send us a pic mate
cheers tony

[remus]

So the rain has stopped today and slabs dried out. Here are some pics then first shows first lot of pointing you will see the joint and slabs are dry.


second pic is off slabs 20 ft away that were pionted next day.You will see that the pointing is sand coloured and soaks up the rain.


Third pic to show part of the patio from the wet end. right of the red line is the area pointed so far.


You said but i wouldnt push a screwdriver into any mortar for at least 72 hours
The pointing was done about 10 days ago.

Kevin

[lutonlagerlout]

oh dear,problem with mortar is it has to be knocked up consistent,
after 10 days i would say the mix must have been inconsistent or too weak,does the fall go towards the damp looking patch??
is water laying there at all??
tell us more
tony ???

[lutonlagerlout]

btw why are there red and yellow bricks adjacent to each other in the wall??
just curious
tony

[remus]

Well we will put it down to a strange bag of cement then. What is the best method of getting the mortar back out again then. Also do I need to take it all out to the full depth of the slabs they are about 32mm.
Yes the damp area is at the lowest end of the patio, but I think the answer is the mortar since the wet slabs start at the point where I started the second mix.
The pic shows part of two extentions and the old house between. This will all be covered up when we have the whole house rendered .Also the rain had been driving against the end of the wall making the colour change.

[bobhughes]

You will have to loosen it with something - (trusty screwdriver?). Whe I was lifting some blocks on my drive I found it useful to suck the stuff out with my vacumn cleaner (One of those with a bin and a very powerful suck).