Concrete Footings - Is there a problem ?

[self builder 123]

Hi

I have had a contractor install concrete footings for decking.

He used a 5:1 ballast to cement mix ( Rugby Premium Cement ).

I happened to notice that the Use By date on the cement had expired 11 days before he used it ? Is this a potential problem with the strength of the concrete or is the date connected with the date the reducing agent ( to avoid an alllergic reaction ) inside the cement expires ?

The footings have been in for 6 days - no frost during this time.

Today I was back filing around the footings and happened to knock a small lump of concrete off one of them.

I was surprised as the footings are hard - you can stand on them no issue.

When I looked at the small piece I noticed that it was damp inside and had a strong smell of wet cement ?

Is this normal - is the concrete simply still curing.

All the footings are below ground - no clay in the soil.

They have been in for 6 days - would it help in curing if I wet them or is it tool late now as the surface has cured ?

I look forward to hearing from anyone who is kindly enough to help

Cheers

 

[RonnyRaygun]

11 days is probably no issue, especially if there are were no lumps of solid cement in the bags.

Also, it's only footings for decking so the loads are going to be nominal. The most important thing is that the load is spread to prevent settlement. Even a weak mix will do this.

Concrete continues to get stronger for months. You can usually start to build on it after 24 hours, 28 day strength is usually specified in the construction industry for concrete, but it will continue to cure for months after that.

The bit you knocked off sounds pretty normal to me for six day old concrete.

 

[ConcreteDrBill]

The shelf life of cement is definitely related to mimimising the risk of allergic reactions (i.e the effective life of the reducing agent that converts soluble chromium (allergen) into insoluble chromium (safe).

As Ronny Raygun says, if the cement in the bag has not gone hard or lumpy it will still perform as expected