What are the benefits of lower water to cement ratios?

Choosing a lower water-to-cement ratio in concrete has significant benefits, particularly in terms of permeability and durability. When the amount of water in the mix is reduced, the resulting concrete tends to be denser and has fewer voids or pores, which contributes to lower permeability. This means that the concrete is less likely to absorb water and other harmful substances, reducing the risk of corrosion of reinforcing steel and enhancing the longevity of the concrete structure.

Additionally, less water in the mix allows the cement particles to bond more effectively, increasing the overall strength and durability of the concrete. This is crucial for septic tank applications, where the material must withstand soil and environmental pressures without degradation over time.

The other options, such as increased water absorption, faster setting times, and greater shrinkage potential, do not offer benefits that align with the objectives of using a lower water-to-cement ratio. Increased water absorption can lead to the weakening of structures, while faster setting times might not ensure proper curing leading to durability issues. Greater shrinkage potential is generally seen as a drawback, potentially leading to cracking. Thus, opting for a lower water-to-cement ratio primarily supports less permeability and enhanced durability, making it the beneficial choice.