Repair & Renovation Guide 139 SOLUTION completely remove the substrate and reinstall a new cement screed for filling or slope creation, by either using the fiber-reinforced cement mortar D-6 (p. 237) or a traditional jobsite mortar mix, fortified by adding the acrylic emulsion additive for mortars D-20 (p. 233) or DUROMAX (p. 251) and polypropylene fibers DUROFIBRE (p. 248). • Create expansion joints, as and where needed, as described in PROBLEM - SOLUTION 6.4. • Waterproof the new substrate with the cementitious brushable waterproofer D-1 (p. 231), fortified by adding the acrylic emulsion additive for mortars D-20 (p. 233), or with D-1 FLEX (p. 231) in 2-3 crosswise coats. • Install the selected lining elements by using a high-quality adhesive (class C2TE S1 or C2TE S2) and grout, as described in PROBLEM - SOLUTION 6.1. NOTE: The mechanical strength and stability of the substrate must always be checked before proceeding with any lining installation. The general rule is to avoid installing lining elements directly over substrates of low mechanical strength, such as EPS lightweight concrete and lightweight mortar mix. 6.6 Marble detachments POSSIBLE CAUSES • Humidity - frost. The absorbency of the grout allows for humidity in the air to penetrate and become moisture and water. If the temperature drops at low levels, the water becomes ice, resulting in its swelling which can lead to marble detachment(s). • Absence of expansion joint. • Installation mortar/adhesive with low adhesive strength. • The grouting was probably done with white cement, resulting in hairline cracks. The moisture, and possibly frost (exterior applications), results in swelling therefore detachment occurs. SOLUTION • Remove the detached marble pieces and clean them from any adhesive/mortar residues. Remove the existing adhesive/mortar from the substrate by mechanical means (hand or power tools), clean from dust, and rinse with plenty of water. • Wet the surface and then reinstall the marble with the marble and granite adhesive D-23 (p. 234). • Grout with the ULTRAFINE VITREOUS CEMENTITIOUS GROUT (p. 275), by adding into the mixing water ACRYLIC EMULSION (p. 274) or D-20 (p. 233), at a mixing ratio of 1: 2 with water, or grout with the two-component epoxy-based grout DUROPOXY (p. 251). • For installations on large exterior surfaces, create an expansion joint at the junction of the vertical (skirting) with the horizontal (floor) surface and then prime it with PRIMER-PU (p. 263). Seal the new joint with the high adhesion polyurethane elastomeric sealant DUROFLEX-PU (p. 249). NOTE: If the detached marble is located on the exterior facade of a building and at a height of more than 2.5 meters from the ground, then according to most local and national building codes, the marble slab, in addition to being installed on the substrate with the appropriate adhesive, must also have mechanical support with special clips or another form of fastener. In this case, it is recommended to consult a specialist or an engineer.
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