Watertight Expansion Joints and Construction Sealants by EMSEAL

Silicone Adhesion to EMSEAL Epoxy

Report on adhesion tests of silicones to EMSEAL 820 epoxy for use as “injected sealant bands” and corner beads

BACKGROUND:

The installation of various of EMSEAL’s impregnated, precompressed foam sealant systems (DSM, SJS, Emshield, Horizontal Colorseal, DSM-FP, SJS-FP, SJS-FP-FR, etc.) requires the product be installed into an EMSEAL-supplied wet epoxy adhesive and then before the epoxy cures, a band of silicone be injected between the factory cured bellows and substrate.

Because the area receiving the injected silicone sealant band has been coated with epoxy, the effective performance of the “system” would require a strong bond between the silicone and the epoxy after both components have cured.

Extensive tests were run to determine the performance of various silicones as sealant bands with particular reference to:

  1. their adhesion to EMSEAL 820 epoxy (which is used to adhere the foam to joint faces)
  2. the effect (if any) on adhesion of different elapsed cure times of the epoxy prior to application of the silicone.

TEST METHOD:

20mm wide x 5mm high strips of the different sealants, separated by 10mm wide x 5mm high strips of form tape, were applied across a 150mm wide slab of fully cured concrete after first coating each strip of concrete with EMSEAL 820 epoxy.

Five groups of strips were set up, each group consisting of the various silicone sealants offered by EMSEAL as components of its product systems.

Each group of the 820 epoxy coatings on the concrete were allowed to cure for the following lengths of time before application of the silicone sealant:

(Group1) 0.5 hour
(Group 2) 1 hour
(Group3) 2 hours
(Group4) 4 hours
(Group5) 24 hours

To ensure sufficient tensile strength in the sealant strips for an upward pull (peel) test, a strip of fine wire mesh was embedded in each strip of sealant. This wire mesh was applied over an initial layer of sealant in such a way that the mesh did not interfere with or block the adhesion of the sealant to the epoxy “substrate”.

Adhesion was tested by hand pull and assessed on a “failure”, “good”, or  “excellent” basis.

SUMMARY OF TEST RESULTS:

All silicone sealants currently offered by EMSEAL as components of its various sealant system products showed “excellent” adhesion to 820 regardless of epoxy “substrate” cure time.

CONCLUSION:

The manner and methods by which EMSEAL requires the field injection of a silicone sealant band beside various of its product systems that are installed into a wet epoxy applied to the substrate faces, produces an excellent bond when installed at any of the epoxy-cure-state time intervals tested.