GT-H90 is a high performance cementitious grout specially developed for precise installation of bridge bearings, pot bearings, spherical bearings, and other structural supports. It is a factory produced dry mix composed of high strength cement, high quality aggregates, efficient admixtures, and optimized micro expansion components. When mixed with water at the recommended ratio, it exhibits ultra high strength, micro expansion, self leveling, and very early strength. This product is mainly used for accurate grouting of pot rubber bearings, spherical steel bearings, and laminated rubber bearings in highway and railway bridges; installation of seismic isolation and damping bearings; pressure grouting of heavy equipment bases under large dynamic and static loads; installation of steel structure bearings in large span spatial structures and stadiums; and bearing installation for precast box girders and T girders on casting beds. It is a critical material ensuring the safety of bridges and large buildings. Its outstanding properties include final compressive strength over 90 MPa, high elastic modulus, rapid early strength development (24h at least 50 MPa), initial fluidity 320-350 mm, 30 min retention at least 300 mm, stable micro expansion (3h vertical expansion 0.15% to 0.30%, 24h to 3h difference 0.05 to 0.15), no shrinkage in any direction, excellent freeze thaw resistance (F50 mass loss ≤2%), impermeability at least P20, oil resistance, good fatigue performance, and strong bond to concrete. Technical parameters: max aggregate size ≤2.5 mm, initial set at least 180 min, final set ≤10 h, 28d bond to steel at least 8.0 MPa, zero bleeding, chloride ion <0.05%, meeting GB/T50448- 2015. For construction, substrate must be cleaned, roughened, and wetted 24 hours prior; formwork should be 5 cm above base plate and sealed. Mix with 13-14% water, add powder gradually, stir to uniform slurry; pour continuously from one side until overflow, tap formwork for venting but do not vibrate. Cure with plastic or wet cover for at least 7 days; protect from loading before strength gain. Suitable temperature 5-35°C; use within 30 minutes; discard set material.