Engineered Concrete for LNG Application

As part of a "Design of Experiments" class, my team was assigned to work with a civil engineering research group on producing a low-thermal conductivity concrete suitable for LNG tank walls through experimentation. The current LNG tank walls are made of concrete layers separated by a thick layer of Perlite (an insulator with a thermal conductivity of 0.03W/m.K). The research team is considering removing the perlite layer and producing a new concrete mixture with low thermal conductivity which would:  

■Lead to 10 - 15 % cost savings

■Shorten construction time from 36 to 24 months

Therefore, my team started experimenting with mixing concrete with insulating materials and testing them to meet the following objectives:

■Thermal conductivity of 0.03 W/m.K

■Compressive Strength of 34.5 MPa - Standard specified strength for concrete for refrigerated liquefied gases

The experiments involved casting and curing different concrete mixtures, embedding thermocouples in them during casting then cooling them in a cryogenic chamber and logging the data through NI DAQ and LabView. The data was then interpreted to calculate the thermal conductivity and the concrete samples were tested on a universal testing machine (compression). The different compositions were mixed & matched according to their performance until a key mixture was identified.



The best mixture the team produced during the assigned experiment period had a thermal conductivity of 0.3 W/m.k at a compressive strength of 15 MPa. This composition included Gabbro as the coarse aggregate (for strength) and wood dust, corafoam and fly ash as fine aggregates (insulating) in addition to water and cement in the following ratios:

Cement - 20%

Water - 15%

Gabbro - 15%

Corafoam - 30%

Dustwood - 10%

Ash  - 10%

© 2019 by Moustafa Raslan. All rights reserved.