What is the effect of reducing the water/cement ratio in concrete?

Reducing the water/cement ratio in concrete has a significant impact on the strength of the hardened concrete. A lower water/cement ratio leads to a denser microstructure in the concrete matrix. This is because less water means that there is less space for voids or pores in the hardened concrete, resulting in increased overall density. As a consequence, the bond between the cement paste and aggregates improves, enhancing the mechanical properties of the concrete, including its compressive strength.

Moreover, the hydration process of the cement is more efficient with a reduced water content, leading to a greater development of strength over time. High strength concrete typically utilizes lower water/cement ratios to achieve desired performance characteristics, making it crucial in structural applications where strength is a primary consideration.

While the other options touch on aspects of concrete properties, they do not directly reflect the primary advantage of a lower water/cement ratio, particularly in terms of enhancing strength.