What is the role of aggregate in the compressive strength of concrete?

The role of aggregate in the compressive strength of concrete is fundamental, as it provides bulk and structural integrity to the concrete mix. Aggregates are used to fill the voids between cement particles, creating a solid matrix once the concrete cures. This solid framework not only supports loads but also contributes significantly to the overall strength and stability of the concrete. Without the inclusion of suitable aggregates, the concrete would be less dense and more susceptible to cracking under stress.

Additionally, the size, shape, and quality of the aggregates can influence the compressive strength of the concrete. Well-graded aggregates provide better packing and reduce the void content, leading to a denser and stronger concrete. The structural integrity provided by the aggregates allows the concrete to perform effectively under various loads and environmental conditions.

Other options present alternative viewpoints, but they do not accurately capture the primary contribution of aggregates to concrete strength. For instance, increasing the water-cement ratio is often detrimental to compressive strength, lowering the weight addresses density but does not directly relate to compressive strength, and enhancing chemical reactions is more associated with the hydration process of cement, not with the role of aggregate itself.