Cast Concrete Manhole Problem

[screamer]

i had to put in a manhole, so i bought a 5t manhole cover that had a plastic outer edge.

i made a form and fixed the plastic outer part to it, then cast the concrete, i also added some colouring to match the paviours.


now the problem is that the concrete is wearing away quite quick, seems to be soft.

how is this not as robust as the precast concrete you get?

canny mind the mix i used for it.

 

[Nige F]

Wasnae strong enough Precast- I think has fine aggregate and a strong mix, and sometimes reinforcing.

 

[screamer]

Wasnae strong enough Precast- I think has fine aggregate and a strong mix, and sometimes reinforcing.

cheers, thats what i was thinking

looks like i'll have to do it again.......sometime

 

[r896neo]

Of course there are always differences but often well mixed and tamped hand mixed concrete is stronger!

Did you perhaps pour it when it was too cold or put too much colouriser in it as concrete or mortar can be badly weakened by large amounts.

 

[screamer]

Of course there are always differences but often well mixed and tamped hand mixed concrete is stronger!

Did you perhaps pour it when it was too cold or put too much colouriser in it as concrete or mortar can be badly weakened by large amounts.

it was poured about april a few years ago, kept inside untill it was dry.

not sure if i should've put in some waterproofer, or could that also make it weak?

i put in enough colouring for it to lighten down, and TBH, the colour has came out a near match to the paviours

 

[Chukka63]

what mix did you use ???

 

[screamer]

what mix did you use ???

can'y remember


but funnily enough, i met a brickie i used to work with years ago and he mentione that the precast stuff could be as strong as 2-1 and the powder colouring does have an effect on it.


cheers lads, looks like i'll maybe get it right this next time

 

[Nige F]

I did wonder about the colouring .Thanks to your brickie M8