Sika Sikadur-52 LP

Sikadur-52 LP is TRSC's default specification for structural epoxy injection of dormant concrete cracks where the engineering intent is to restore monolithic structural action. The product earns its specification slot for two reasons: it is genuinely structural-grade (cured tensile strength exceeds the concrete substrate, producing concrete-failure bond mode in pull-off testing), and its low viscosity (~290 mPa.s) permits penetration into cracks as fine as 0.2 mm width, which covers the great majority of structural crack widths encountered in remediation work. The most common specification pitfalls TRSC encounters in the field are: (1) crack activity classification — Sikadur-52 LP is appropriate only for dormant cracks; active cracks (those subject to ongoing thermal, shrinkage or live-load movement) will fracture the cured resin within months of injection, returning the crack to its uninjected condition; the engineering judgement on dormancy requires monitoring over a period (typically 4-12 weeks of crack-monitor data) before the injection specification is issued; (2) crack moisture — Sikadur-52 LP is not moisture-tolerant; cracks that are wet, weeping or carrying surface efflorescence will not bond to the resin and the injection will fail; cracks must be dried (compressed air, heat, or ambient drying period) before the resin is introduced; (3) injection technique — the resin must be introduced under pressure from one end of the crack, with the next port opened only when resin appears at it, working progressively along the crack length; field installations that pump simultaneously into multiple ports trap air pockets that compromise the structural restoration; TRSC specifications include the injection sequence as a witness hold point, with the contractor required to demonstrate the technique on the first crack. Site QA includes batch numbers, ambient and substrate temperature recording at the start of each injection, photographic record of port locations and the injection sequence, and post-injection core sampling at agreed frequency to verify resin penetration through the crack depth. The product was used on Q1 Tower post-cyclone structural restoration where impact-damage cracks in concrete elements required structural injection as part of the make-safe and full-restoration sequence.