Shrinkage Reducing Admixture

Shrinkage Reducing Admixture are special chemical additives used in concrete to minimize the extent of shrinkage that occurs as the concrete hardens and dries. Shrinkage can cause cracking, reduce durability, and compromise the structural integrity of concrete structures. SRA is an innovative liquid chemical admixture that is specifically formulated to reduce drying shrinkage. Compared to normal concretes, It provides enhanced performance through a significant reduction in shrinkage strain and a reduced number of harmful cracks.

Benefits:

• Significantly reduce plastic shrinkage cracks during the initial setting phase.
• Minimize drying shrinkage over time.
• Improve durability by preventing crack formation.

Usage:

• Usually added during batching or mixing.
• Proper dosage is key to achieving desired Shrinkage Reducing Admixture.

Additional Notes:

• Shrinkage-compensating concrete can also be used, which incorporates expansive cement to counteract shrinkage strains.

SRA is suitable for various concrete types, designed to enhance crack resistance, volume stability, and durability. In ordinary concrete, it effectively reduces crack formation; in high-performance concrete, it further improves volume stability and durability; SR-100P for self-leveling mortar, it reduces plastic shrinkage and enhances self-leveling performance; in exposed concrete, it helps minimize surface cracking and improves surface quality.

The advent of shrinkage reducers offers a novel solution to this challenge. As an admixture that effectively reduces the self-shrinkage and drying shrinkage rates of concrete and mortar, shrinkage reducers overcome the limitations of traditional crack prevention methods, providing an effective means to prevent shrinkage cracking in concrete. Reduction agents primarily minimize concrete shrinkage by lowering the surface tension of the pore solution within the concrete, demonstrating particularly pronounced inhibitory effects on early-stage shrinkage in dry environments. Compared to expansive agents, reduction agents offer more flexible application conditions in engineering projects. To fully leverage their role in reducing shrinkage cracking in concrete, reduction agents must meet a series of stringent requirements, including maintaining surface activity and stability within highly alkaline solutions.

Shrinkage reducers primarily reduce shrinkage through physical mechanisms, with their components predominantly consisting of organic compounds. In contrast, expansive agents rely on chemical expansion and are typically inorganic compounds. It is precisely due to these differing mechanisms of action that shrinkage reducers demonstrate superior crack resistance compared to expansive agents.

Shrinkage reducers decrease the surface tension of capillary solutions within concrete, thereby reducing capillary forces. This effectively minimizes drying shrinkage and autogenous shrinkage in concrete, operating purely through physical mechanisms. In contrast, expansive agents rely on chemical reactions with cement hydration products, primarily forming crystalline expansive products like calcium aluminate hydrate (CAH), which generate expansive forces to counteract concrete shrinkage. This process requires substantial water participation. However, under poor curing conditions—such as insufficient moisture—the crack-resistant efficacy of expansive agents becomes limited. Conversely, shrinkage reducers demonstrate more pronounced shrinkage-reducing effects in dry environments.