ACI 305 nomograph for 3D concrete printing

ACI 305 calculates the rate of evaporation from concrete slabs. In 3D concrete printing, evaporation matters more, because no formwork exists to keep the moisture in. Use this tool to evaluate the printing conditions. It gives a measure of the risk of shrinkage and cracking.

How to use

Step 1Set the ambient temperature to match your environment.
Step 2Set the relative humidity to match your environment.
Step 3Set the expected or current printing temperature.
Step 4Set the air movement, or pick a preset.
Step 5Read the evaporation rate against the two thresholds: 0.240 kg/m²/h.

Printing conditions

Step 1Ambient temperature, °C °C
Step 2Relative humidity, % %
Step 3Printing temperature, °C °C
Step 4Air movement, km/h km/h

Advanced

3DCP working threshold, kg/m²/h kg/m²/h

The default is 0.25 kg/m²/h. ACI quotes that value for mixes that bleed little, and printing mortars bleed little. No field record yet fixes the value for printed layers. A site with its own evidence sets its own line. The ACI limit of 1.0 is fixed.

Evaporation rate

0.240 kg/m²/h Pass 0.010 below 3DCP working threshold

Set values

Ambient temperature 20 °C · Relative humidity 55 % · Surface temperature 20 °C · Air movement 8 km/h (Outdoor)

Verdict
Pass below 0.25
Shrinkage risk 0.25 to 1.0
High shrinkage risk 1.0 and above