What is the dosage ratio of high-efficiency water reducer in GRC?

The dosage of high-range water reducers in GRC ranges from 1.0% to 2.0% of the cementitious material mass, and must be adjusted according to the water reducer type, cementitious system, and construction process. Qinglong determines the optimal dosage through experimental optimization, achieving a water reduction rate of ≥30% while ensuring GRC workability and strength stability, meeting the needs of different production scenarios.

I. Core Dosage Range and Classification-Based Adaptation

The dosage must be precisely adjusted based on the water reducer type and GRC application. Ordinary high-range water reducers: naphthalene-based and aliphatic types, dosage 1.5%-2.0%, water reduction rate 25%-30%, suitable for ordinary GRC components; Qinglong uses naphthalene-based water reducers for ordinary GRC at a dosage of 1.8%. High-performance high-range water reducers: polycarboxylate-based, dosage 1.0%-1.5%, water reduction rate 30%-40%, suitable for high-strength, thin-walled GRC components; Qinglong uses polycarboxylate-based water reducers for double-curved and openwork GRC at a dosage of 1.2%. Retarding high-range water reducers: dosage 1.5%-2.0%, suitable for construction in high-temperature environments; used in Qinglong's summer production at a dosage of 1.8%, extending the initial setting time to over 4 hours. Early-strength high-range water reducers: dosage 1.2%-1.8%, suitable for projects with tight schedules; used in Qinglong's emergency projects at a dosage of 1.5%, reaching 80% of design strength at 7 days.

II. Key Factors Affecting Dosage Adjustment

The actual dosage must be dynamically optimized according to specific conditions. Cementitious system: low-alkali sulphoaluminate cement has good compatibility with polycarboxylate-based water reducers, so the lower dosage limit can be used; Portland cement requires an appropriately higher dosage—Qinglong's dosage for the low-alkali cement system is 0.3%-0.5% lower than that for the Portland cement system. Aggregate gradation: when the fine aggregate content is high, the dosage must be increased by 0.2%-0.3% to ensure flowability—when Qinglong's fine aggregate (0.15-0.3mm) content is 60%, the dosage is increased to 1.4%. Construction process: spray-up GRC requires higher flowability, with a dosage 0.1%-0.2% higher than cast GRC—Qinglong's sprayed GRC dosage is 0.15% higher than that of cast GRC. Ambient temperature: for every 10°C increase in temperature, the dosage increases by 0.1%-0.2%—Qinglong's summer dosage (above 35°C) is 0.3% higher than in winter.

III. Corporate Standards for Dosage Control and Experimental Optimization

Qinglong has established a strict dosage control process to ensure optimal performance. Experimental optimization process: before using a new water reducer or new cementitious system, 5 groups of trials at different dosages (0.8%, 1.2%, 1.5%, 1.8%, 2.0%) are conducted, measuring flowability and strength to determine the optimal dosage. Production control: an automated batching system is used with a dosage error of ≤±0.1%; Qinglong's batching system achieves a precision of ±0.05%. Performance verification: the optimal dosage must meet a spread of 650-750mm and a 28-day compressive strength of ≥60MPa; when Qinglong tested the polycarboxylate-based water reducer at a dosage of 1.2%, the spread was 700mm and strength reached 68MPa. Prohibitions: the dosage must not exceed 2.0%, otherwise excessive retardation and strength reduction will occur; Qinglong strictly prohibits overdosage and tests strength and setting time before shipment.