The mini-heatwave
that settled upon many parts of the UK in June provided a welcome reminder that
hot, sunny weather wasn’t necessarily the preserve of our compatriots across the
continent.
Sweltering temperatures, however pleasant they might be for camels or
ice cream vendors, do not make ideal building conditions, particularly when it
comes to concreting.
For
concrete to be placed and finished correctly, it needs to remain workable. In
hot weather, moisture is drawn from the mixture more quickly, which can lead to
it setting too rapidly for the user’s requirements. For instance, a 300mm-thick
slab requires two loads of concrete to fill a mould.
Timings
are tight, and it’s not unknown for the first load to set before the second load
is even delivered – particularly during hot weather. It only takes the second
delivery load to be delayed by traffic, for example, for the process to fail.
Fresh cement that’s poured onto an already-set and compacted base can lead to
cold joints and unevenness.
Fresh
loads of cement should knit together to form one homogenous mass. For this to
happen – concrete generates its own heat, so climatic conditions are only part
of the hydration issue – it helps if the setting process is decelerated. Here’s
where the availability of a product range such as Sikatard is such a huge
benefit.
Sikatard
is an admixture in liquid form developed for the control of cement hydration. It
coats the cement particles to prevent infusion and slow the drying-out process.
This ensures the concrete mix is stabilised and prevents its setting for hours
or even days. Sikatard, which conforms to the requirements of BS EN 934-2 Table
8, can also be used in steel reinforced concrete construction without
restriction. Its stabilising properties ensure the distribution of stresses
throughout the reinforcement encapsulated in the concrete isn’t
compromised.
Sika
PilePak is another product proven to eliminate moisture escape from concrete.
Its use during cast in situ concrete piling projects eases steel reinforcement
fitting. Sika PilePak acts as a thickening agent which helps retain moisture
within the concrete’s cement paste. It’s added to the concrete during batching
then delivered to site.
Dry or
gravel-based ground absorbs water from cement like a sponge, making steel
reinforcement insertion incredibly difficult, which could affect the concrete,
and ultimately, the infrastructure’s stability. Sika PilePak ensures consistency
and workability of the concrete over a prolonged period of time, helping avoid
any concrete problems at any one pile position.
With the
government announcing a total of 250,000 new homes are needed annually to keep
pace with demand, speed is key to developers helping fulfil this requirement
without compromise to safety or quality. Thankfully, in Sika PilePak and the
Sikatard range, the industry has the products with which to build a stable base
to help meet our future housing needs – however hot the
weather.
