Laminated Ferrocement

LFC

LFC Tests on panels

6-13-2011 by Abe Connally, [1]

Panel 1 - 1 layer 3/8" hardware cloth, 36.5" X 20.75" - 757 si, 5.26 sf

• 5/16" - 3/8" thick
• Cured for 3 days
• 17lbs, 3.23 lbs/sf

Panel 2 - 2 layers 3/8" hardware cloth, 36.5" X 20.375" - 744 si, 5.17 sf

• 3/8" - 7/16" thick
• Cured for 3 days
• 22lbs, 4.25 lbs/sf

Tests - panels were placed on bricks, spaced 14" apart. Weight was placed in center of panel, between brick supports.

• Test 1 - 1 gallon water @ 8lbs on 2.25 si, 3.55 psi
• Test 2 - 1 gallon water @ 8lbs on 1.5 si, 5.33 psi
• Test 3 - human @ 173 lbs on 46 si, 3.76 psi

Results

• Test 1, panel 1 - troweled side up - no visible sag or cracks
• Test 1, panel 2 - troweled side up - no visible sag or cracks
• Test 2, panel 1 - troweled side up - no visible sag or cracks
• Test 2, panel 2 - troweled side up - no visible sag or cracks
• Test 3, panel 1 - troweled side down - visible sag but no cracks
• Test 3, panel 2 - troweled side down - slight visible sag but no cracks
• Test 3, panel 1 - troweled side up - extreme sag and panel snapped along brick support
• Test 3, panel 2 - troweled side up - visible sag but no cracks

Troweled side has 1/8" less concrete on mesh

Conclusions

Both panels survived psi ratings for tank design (3.44 psi), however because troweled side has less concrete, it is a weaker side of panel in compression. Suggest using formed side as inside of tank, so that the troweled side will be in greater tension (more mesh, less concrete). Panel 2 with 2 layers of mesh seem to be stronger in all tests.

I think these would do just fine as roof tiles or panels, especially if shaped to take advantage of concrete's compression strength. For a water tank, although they survived the psi required for an 8ft tall tank, I think more testing is required.

More Information

• LFC Panel Water Tank
• LFC Channel Roof