ما قضايا القلوية التي يجب الانتباه لها عند استخدام أسمنت السلفوألومينات في GRC؟

The alkalinity of sulphoaluminate cement (pH 10.5-11.5) is significantly lower than that of Portland cement (pH 12.5-13.5), which is a double-edged sword for the long-term durability of GRC. On one hand, a low-alkalinity environment slows the corrosion of glass fibers; on the other hand, it may affect the degree of cement hydration and early strength development.

In the production of rapid-hardening GRC components for the Shenzhen Metro, Qinglong resolved this contradiction through a composite cementitious material system: sulphoaluminate cement (60%) was blended with Portland cement (20%) and silica fume (20%), keeping the system's pH within the ideal range of 11.8-12.2. This mix achieved a 4-hour compressive strength of 15 MPa, and after a 360-day accelerated aging test, fiber strength retention was 82%. The project also added a lithium salt setting accelerator (0.02%-0.05%), which ensured the setting times required for construction (initial set ≥25 min, final set ≤40 min) while avoiding incomplete hydration caused by excessively low alkalinity.

Alkalinity Control Technology

Blending Portland cement adjusts the pH to 11.5-12.5. Active admixtures are added to consume free Ca(OH)₂. Acidic setting regulators are used to control the rate of alkalinity increase. A real-time pH monitoring system has been established.

Coordinated Strength Development Measures

Composite activators promote hydration in a low-alkalinity environment. The curing regime is optimized (temperature 30-40°C, humidity ≥95%). Nano crystal nuclei are added to accelerate the formation of hydration products. Steam curing is used to enhance early strength.

Fiber Protection Strategies

High-zirconia fibers (ZrO₂ ≥18%) are selected. Alkali-resistant coatings are applied to fiber surfaces. Local alkalinity around fibers is controlled. The fiber-matrix interface structure is optimized.

Durability Assurance System

Accelerated aging tests verify long-term performance. An alkalinity-strength-durability relationship model has been established. An alkalinity warning threshold is set (pH ≤11.0). The performance of in-service components is tested regularly.

The application of sulphoaluminate cement requires systematic technical support. Through extensive experiments, Qinglong GRC has mastered comprehensive alkalinity control technology.