How Do Admixtures Improve GRC Performance? Which Admixtures Are Prohibited?

Admixtures are a key component in enhancing GRC performance, and their scientific use can significantly improve the workability, mechanical properties, and durability of GRC. Based on 28 years of mix design experience, Qinglong Group has systematically summarized the improving effects of admixtures on GRC performance and clearly defined the scope of prohibited admixtures, providing a guarantee for the quality of GRC products.

High-range water reducers are among the most commonly used admixtures in GRC, whose main function is to lower the water-binder ratio and increase material density. Qinglong Group's test data show that, while maintaining the same flowability, adding a high-range water reducer can reduce the water-binder ratio from 0.4 to below 0.3, thereby increasing the compressive strength of GRC by more than 20% and improving its impermeability by an order of magnitude. In the translucent UHPC project at Shanghai Century Plaza, optimizing the type and dosage of the water reducer achieved a unity of high flowability and high strength.

Polymer emulsion admixtures have a significant effect on improving the toughness and bonding properties of GRC. Qinglong Group typically adds an appropriate amount of acrylate emulsion to its GRC formulations. This polymer forms a continuous film within the cement matrix, effectively improving the material's flexibility and impact resistance. Test data show that GRC containing polymer emulsion can achieve an increase in ultimate tensile strain of more than 50% and a 2-3 fold increase in flexural toughness. This is especially important for exterior wall panels that need to resist wind-induced vibration and thermal stress.

Regarding prohibited admixtures, Qinglong Group explicitly stipulates that admixtures containing chlorides are strictly forbidden in GRC. Although early-strength agents such as calcium chloride can increase early strength, they introduce chloride ions and aggravate the risk of steel reinforcement corrosion. In addition, admixtures that undergo adverse chemical reactions with cement hydration products must also be avoided; for example, certain sulfate-based admixtures may cause volume instability. In the Algeria Hotel project, we ensured the long-term stability of GRC components in high-temperature, high-humidity environments through rigorous admixture screening.

Qinglong Group also pays particular attention to the compatibility between admixtures and cement. Before new projects commence, the technical team conducts systematic compatibility tests to ensure that admixtures will not cause abnormal workability of the mix or degraded performance. Through this scientific and rigorous approach, Qinglong Group tailors the optimal admixture solution for each project, ensuring that GRC products deliver their best performance.