How can a concrete hydration heat inhibitor effectively control the early hydration heat release rate without significantly delaying strength development?
Publish Time: 2026-02-12
In large-volume concrete projects, if the large amount of heat released by the cement hydration reaction cannot be dissipated in time, it will lead to a sharp rise in internal temperature, while the surface dissipates heat faster, forming a significant internal and external temperature difference, which in turn induces temperature stress and early thermal shrinkage cracks. Traditional solutions often rely on retarders, admixtures, or cooling water pipes, but these often come with problems such as delayed strength development, extended construction periods, or increased costs. A hydration heat inhibitor has emerged to address this issue—it does not simply delay setting, but rather, based on a deep understanding of the hydration kinetics of silicate cement, precisely controls the hydration heat release process, effectively reducing peak temperatures while essentially preserving early and even later strength.1. Targeting the initial hydration of C3A and C3SIn cement clinker, tricalcium aluminate and tricalcium silicate are the main sources of early heat release, especially C3A, which reacts rapidly within minutes of adding water, forming the initial heat release peak; C3S dominates the main heat release stage within 12–48 hours. A novel hydration heat inhibitor, through molecular design, allows its active component to preferentially adsorb onto the surface of C3A and C3S particles, forming a reversible, non-dense complex film. This film does not completely block hydration, but rather moderately slows down the rate of ion dissolution and hydration product nucleation, thus "flattening" the first peak of the exothermic curve and shifting the main exothermic peak backward by 6–12 hours. This regulation is not a complete inhibition, but rather allows the hydration reaction to proceed more uniformly and continuously, avoiding concentrated bursts of heat.2. Maintaining Total Hydration and Ensuring Normal Strength DevelopmentThe key breakthrough lies in the "phased" and "self-dissociating" characteristics of this inhibitor. As the pH of the hydration environment changes or hydration products accumulate, the inhibitory film gradually dissociates or is covered by newly formed C-S-H gel within 24–72 hours, and the hydration reaction then recovers to a near-normal rate. Therefore, although the early strength may be slightly reduced, the strength at 3 days, 7 days, and 28 days is almost unaffected, and may even be slightly improved due to more complete hydration. This is fundamentally different from traditional retarders, which cause overall hydration delay and long-term strength lag. The hydration heat inhibitor does not reduce the final degree of hydration; it merely optimizes the heat release sequence.3. Synergistic effect with mineral admixtures to achieve "dual temperature control"In practical applications, hydration heat inhibitors are often used in combination with mineral admixtures such as fly ash and slag powder. The admixtures themselves have "micro-aggregate filling" and "secondary hydration" effects, which can further reduce the total heat of hydration; while the inhibitor precisely controls the initial peak heat release of cement. The synergy of the two avoids the problem of insufficient early strength caused by relying solely on high admixture dosages and enhances the temperature control effect. For example, in the concrete of a large hydropower station dam, using 15% fly ash + 0.3% hydration heat inhibitor resulted in a 12°C lower maximum internal temperature rise compared to the benchmark mix, while the 3-day strength still met the demolding requirements.4. Does not affect workability and durability, adaptable to modern construction needsThese inhibitors are mostly in liquid form, exhibiting good compatibility with polycarboxylate superplasticizers and not causing bleeding, segregation, or abnormal setting. Their molecular structure does not contain harmful components such as chloride ions or alkali metals, posing no risk of steel reinforcement corrosion. Furthermore, by reducing temperature cracking, they actually improve the impermeability and long-term durability of concrete. In high-temperature construction during summer or in the pouring of ultra-thick foundation slabs, it provides engineers with a new approach to "internal temperature control," effectively preventing early cracking without the need for complex cooling systems.In summary, the new concrete hydration heat inhibitor achieves a technological breakthrough of "reducing heat without reducing strength" through precise intervention at the molecular level. It is not simply "applying the brakes," but rather equipping cement hydration with an "intelligent speed regulator," making the heat release process more stable and controllable. This innovation not only improves the structural safety of large-volume concrete but also provides strong support for green, efficient, and intelligent construction.
