Broken slats

blonde10

Hi all,
Just wondering what's the life span of slats,neighbour had gang slats break last night,3 cows fell into the tank,lucky enough slurry was out,only about 3ft of ****e on the bottom,some job getting them out..slats are in since 2002,what is the life span of them..to me that's a bit soon to be replacing....what's yer thoughts...??

mahoney_j

blonde10 wrote: »

Hi all,
Just wondering what's the life span of slats,neighbour had gang slats break last night,3 cows fell into the tank,lucky enough slurry was out,only about 3ft of ****e on the bottom,some job getting them out..slats are in since 2002,what is the life span of them..to me that's a bit soon to be replacing....what's yer thoughts...??

Sounds a bit soon to be going I replaced slats on a tank that we’re put on 42 years ago last autumn ,90% we’re fine but some were in bad shape 10 ft 6 slats

patsy_mccabe

Do you know the length and make of the slats?

_Brian

We changed three bays of single slats 4 years ago.
They were in 40 years. Doubt the replacements will last as well.

Good loser

mahoney_j wrote: »

Sounds a bit soon to be going I replaced slats on a tank that we’re put on 42 years ago last autumn ,90% we’re fine but some were in bad shape 10 ft 6 slats

I replaced slats in 2017 that went in circa 1990. 10ft 6 in.



Were spalling pretty badly on top; chunks had come off top exposing rebar;
at least three bars fell into slurry below. When tank is low or empty it might be possible to look along length of tank underneath to check for rebar hanging down. When removed concrete was well split but none actually sagged.


Specs higher now as far as I know.

wrangler

Good loser wrote: »

I replaced slats in 2017 that went in circa 1990. 10ft 6 in.



Were spalling pretty badly on top; chunks had come off top exposing rebar;
at least three bars fell into slurry below. When tank is low or empty it might be possible to look along length of tank underneath to check for rebar hanging down. When removed concrete was well split but none actually sagged.


Specs higher now as far as I know.

I hear some guy's talking about using phone with a selfie stick to examine the under side of slats

patsy_mccabe

How about a Telescopic Inspection Mirror;

https://www.amazon.co.uk/Rolson-60515-Telescopic-Inspection-Mirror/dp/B008H06O46

grassroot1

Was there something about using a straight edge and spirit level to check if the slats are sagging?

patsy_mccabe

Photos of damaged slats at Ploughing 2018. Banagher slats had them on show.

Bleating Lamb

patsy_mccabe wrote: »

How about a Telescopic Inspection Mirror;

https://www.amazon.co.uk/Rolson-60515-Telescopic-Inspection-Mirror/dp/B008H06O46

Would rather chancing that device down between slats than an iPhone on a selfie stick!!

Aravo

Changed 4 bays of slats a few years back. Nearly 40 years old. Exactly like the banagher photograph. Some had even more chunks removed from underneath. No sagging. Slats were 12ft, they had one joint location at the centre like the banagher photograph. The newer ones have 2 joint locations. Say for 12ft, joint at 4ft, 4ft. And the newer ones were an inch deeper.

Farmer

Roughly how much are you looking at for a 12' gang slat nowadays or for a bay of 12' slats?

Muckit

Aravo wrote: »

Changed 4 bays of slats a few years back. Nearly 40 years old. Exactly like the banagher photograph. Some had even more chunks removed from underneath. No sagging. Slats were 12ft, they had one joint location at the centre like the banagher photograph. The newer ones have 2 joint locations. Say for 12ft, joint at 4ft, 4ft. And the newer ones were an inch deeper.

How did you cop in the end that they needed changing?

Reggie.

patsy_mccabe wrote: »

Photos of damaged slats at Ploughing 2018. Banagher slats had them on show.

Suppose they looked ok from the top

patsy_mccabe

Reggie. wrote: »

Suppose they looked ok from the top

Can't remember exactly, but I think they were ok, except for small cracks.

Anyone notice anything revealing in the full pic? It would explain why they fail.

Aravo

Muckit wrote:

How did you cop in the end that they needed changing?

A few were chipping at the top. We had replaced the end slats for manhole slats in 2007, so from this, had a good idea how the others were. Plus the others were taking weight not like the end ones. The grant was out to replace, so availed of it. Banagher came, measured up. All new ones fitted in a day. Good job.

If one has some double slats, I would remove one and have a look. If one needs to go, they all need to go. That banagher photo is a good overview of what happens.

Reggie.

patsy_mccabe wrote: »

Can't remember exactly, but I think they were ok, except for small cracks.

Anyone notice anything revealing in the full pic? It would explain why they fail.

Metal too close to the edge of the concrete

Say my name

Reggie. wrote: »

Metal too close to the edge of the concrete

It'd be no harm if that metal was galvanized before use too.
Or even bleedin painted.
It wouldn't stop rust travelling through the center of the steel but it would slow it down travelling between the concrete, steel edge.

patsy_mccabe

Reggie. wrote: »

Metal too close to the edge of the concrete

It's part of the problem. If you look at the under side of the central cross beam, it is perfect. So are the undersides of the ends. It's to do with stress. Concrete is very strong in compression but weak in tension. The underside of the slats is in tension load (simple bending) and so the rebar is required there to strengthen it. With the constant loading and unloading as cattle walk on it, all it takes is a small crack to form and the moisture gets in. It rusts the rebar, it expands and cracks it even more. The cross beam stiffens it that bit more and so no failure there.
I've read in the journal a few times that's it the slurry underneath that rots them, it's not. It's the stresses first. That leads to the rusting after. That's what's worrying about these longer slats. When you double the width of a gang slat, it has to be 4 times stronger to carry the same load on it. Time will tell if all these extra wide slats are a good idea.

From videos I've seen too, all these slats are dry cast. Does this weaken the final concrete? I'd imagine, it would. Wet poured concrete would be a lot better, but a much slower process.

grassroot1

Does anyone have pre-stressed slats in place how do they fair.
What life can you expect from slats?