Concrete Precast Elements: Early strength and durability

Precast concrete is done by casting concrete in a reusable mould and then curing it in a controlled environment. The part is then transported to the construction site and fitted into place.

The concrete hardening process is a time-consuming step, generally carried out with the application of heat or steam curing – both highly energy-consumptive. The SikaRapid® technology aims to improve this process. Besides enhancing the early strength and durability of the concrete, it reduces to half the steam curing time.

50% less steam curing

Two alternative concrete mixes for the same application (W/C ratio of 0.42) were evaluated. The evaluation took into account that for the mix containing SikaRapid®-1, 50% less steam curing time is needed. The LCA is from cradle-to-gate, which includes all life cycle stages from raw material extraction and logistics to manufacturing and packaging. The inputs necessary for the steam curing are also included.

Input Water, Cumulative Energy Demand and Global Warming Potential

Results and Conclusions: To assess the gains from using SikaRapid in precast concrete elements, the Input Water, Cumulative Energy Demand (CED) and Global Warming Potential (GWP) for both concrete systems are shown below.

The Input Water shows the consumption of water for the concrete production. The GWP measures the potential contribution to Climate Change, focusing on emissions of greenhouse gases (for example CO₂, CH₄). CED is the total amount of primary energy from renewable and non-renewable resources.

Sika Rapid: The net gain of water input for the mix with SikaRapid-1 is 0.06 m3
yes
Net gain of input water

The net gain of water input for the mix with SikaRapid®-1 is 0.06 m3 due to the reduction to half of the steam curing. This is equivalent to saving 60 one liter bottles of water per cubic meter of concrete.

yes
Global Warming Potential (GWP)

In terms of GWP, it 'costs' 2 kg CO₂ to produce the SikaRapid®-1 amount, but the overall net gains are tenfold that value (21 kg CO₂) for each cubic meter of concrete.

 

Cumulative Energy Demand (CED): overall net gains are 440 MJ.
yes
Cumulative Energy Demand (CED)

In terms of CED, it 'costs' 54 MJ to produce SikaRapid®-1 amount, but the overall net gains are 440 MJ, which is equivalent to saving 10 liters of oil per cubic meter of concrete (Costs vs. Savings factor of 1:8).