Hello. Please can anyone advise on a prob we have at the moment:
My husband has laid a driveway for someone, he followed all rules and regs, and after laying the crazy paving used a mix of 4:1 to fill in the gaps between the slabs ( sorry I'm not very well informed on the proper terms...)He then hose piped it down, but its been almost 3 days now and the sand/cement mix is just as it was-it hasnt gone hard at all! He has been told he needs to remove all the sand/cement and re-do it all. Is this correct or is there a way around it? He's having a bit of a nervous breakdown :p about it all so I though I'd try and help by checking the Web, and came across this great site! Do hope someone can give him some help, he almost broke his back doing it the first time, and the thought of doing it all again....o dear.
Kind regards.
Help please! - Cement wont go hard!!
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dick turpin
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- Location: epping essex
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steve r
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Sounds as though he has washed all the cement from the joints, leaving just sand.
He will need to remove it and start again.
Have a look at this page pointing and jointing and easy on the water best to use a watering can fitted with a fine rose.
He will need to remove it and start again.
Have a look at this page pointing and jointing and easy on the water best to use a watering can fitted with a fine rose.
Steve Rogers
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Tony McC
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Steve is proabably right - if you use copious quantities of water to wash off, you do run the risk of washing out the cement from the top few millimetres of the mortar in the joints. When using a wet grout or slurry, we try to use a stronger-than-normal mix, say 3:1 instead of 4:1, and we use as little water as poss when it comes to washing off.
I'd also check the cement used: was it fresh? The most common cause of unset mortar/concrete when DIYers are involved is that they used some cement they've had in the shed for a couple of years. Although it is still a powder (just!), it will have 'perished' and lost its ability to set hard (I won't bore you with the chemistry) - it just sets enough to bind the sand but not to resist abrasion or trafficking.
With contractors, the most common cause of proeblems with unset mortars/concrete is sugar-contamination. Just a teaspoon of sugar is enough to prevent proper setting (curing) of a barrowful or mortar or concrete. It only need someone to lob in a half-cup of excessively sweetened tea to bollix a whole mix!
I'd also check the cement used: was it fresh? The most common cause of unset mortar/concrete when DIYers are involved is that they used some cement they've had in the shed for a couple of years. Although it is still a powder (just!), it will have 'perished' and lost its ability to set hard (I won't bore you with the chemistry) - it just sets enough to bind the sand but not to resist abrasion or trafficking.
With contractors, the most common cause of proeblems with unset mortars/concrete is sugar-contamination. Just a teaspoon of sugar is enough to prevent proper setting (curing) of a barrowful or mortar or concrete. It only need someone to lob in a half-cup of excessively sweetened tea to bollix a whole mix!
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