混凝土是由水泥、水和砂、石按适当比例配合、拌制成混合物,经过一定时间硬化而制成的。其中砂、石起骨架作用,称为骨料;水泥与水形成水泥浆,水泥浆包裹在骨料表面并填充空隙。在硬化前,水泥浆起润滑作用,使新拌的混凝土具有一定流动性,便于施工。水泥浆硬化后,将骨料胶合成一个坚实的整体,使混凝土产生一定的强度。混凝土强度的高低主要与水泥标号、水泥用量和水灰比有关。当用同一种水泥(品种和标 Concrete is made of cement, water, sand, and stone in appropriate proportions, mixed into a mixture and hardened after a certain period of time. Among them, sand and stone play the role of skeleton, which is called aggregate; cement and water form a cement slurry, and the cement slurry is wrapped on the surface of the aggregate and fills the gap. Before the hardening, the cement slurry acts as a lubricant, which gives the fresh concrete a certain fluidity and facilitates construction. After the cement is hardened, the aggregates are glued together into a solid body that gives concrete a certain strength. The strength of concrete is mainly related to the cement number, cement content and water-cement ratio. When using the same cement (variety and standard