While a mixture of cement and water (grout) forms the basis of concrete, it cannot directly replace it for construction purposes due to several inherent limitations.
Shrinkage: Grout undergoes significantly higher shrinkage compared to concrete with the same mass. This substantial volume reduction can lead to cracking, compromising the structural integrity and durability of the element.
Creep: The creep effect, which is the gradual deformation of material under constant load, is much more pronounced in grout than in concrete. This excessive creep can lead to long-term structural issues, including excessive deflections and potential instability.
Heat of Hydration: The chemical reaction between cement and water (hydration) generates a significant amount of heat. In grout, this heat of hydration is even higher than in normal concrete due to the absence of aggregates, which typically act as a heat sink. This elevated temperature can cause thermal cracking, further weakening the structure.
Therefore, while grout has its applications in specific scenarios like grouting of post-tensioning ducts or filling voids, it cannot be used as a substitute for concrete in structural elements. Concrete, with its carefully balanced proportions of cement, water, and aggregates, offers superior performance in terms of shrinkage, creep, and thermal stability, making it the preferred choice for most construction applications.