Concrete is a composite construction material composed primarily of aggregate, cement, and water. There are many formulations, which provide varied properties. The aggregate is generally a coarse gravel or crushed rocks such as limestone, or granite, along with a fine aggregate such as sand. The cement, commonly Portland cement, and other cementitious materials such as fly ash and slag cement, serve as a binder for the aggregate. Various chemical admixtures are also added to achieve varied properties. Water is then mixed with this dry composite, which enables it to be shaped (typically poured) and then solidified and hardened into rock-hard strength through a chemical process called hydration. The water reacts with the cement, which bonds the other components together, eventually creating a robust stone-like material. Concrete has relatively high compressive strength, but much lower tensile strength. For this reason it is usually reinforced with materials that are strong in tension (often steel). Concrete can be damaged by many processes, such as the freezing of trapped water.
混凝土是一种复合建筑材料主要由骨料，水泥，水。有许多配方，提供多种多样的性质。骨料一般粗砾石或碎石岩如石灰石，花岗岩，随着细集料砂等。常见的水泥，波特兰水泥等胶凝材料，如粉煤灰、矿渣水泥，作为粘结剂的骨料。各种化学外加剂也将实现不同特性。水混合干燥的复合，使其形成（通常是投入）和固化和硬化成岩石硬实力通过化学过程称为水合。水与水泥，债券的其他部分一起，最终建立一个强大的石头等材料。混凝土具有较高的抗压强度，但较低的抗拉强度。出于这个原因，它通常是钢筋材料强拉（通常是钢）。具体可以破坏许多过程，如冻结被困水。
Workabilityis the ability of a fresh (plastic) concrete mix to fill the form\/mold properly with the desired work (vibration) and without reducing the concrete's quality. Workability depends on water content, aggregate (shape and size distribution), cementitious content and age (level of hydration) and can be modified by adding chemical admixtures, like superplasticizer. Raising the water content or adding chemical admixtures increases concrete workability. Excessive water leads to increased bleeding (surface water) and\/or segregation of aggregates (when the cement and aggregates start to separate), with the resulting concrete having reduced quality. The use of an aggregate with an undesirable gradation can result in a very harsh mix design with a very low slump, which cannot be readily made more workable by addition of reasonable amounts of water. workabilityis能力的新鲜（塑料）混凝土配合填写表格\ /模具适当所需的工作（振动）和不降低混凝土的质量。性取决于水含量，骨料（形状和大小分布），水泥含量和年龄（水合程度），可以修改添加化学外加剂，如高效减水剂。提高水含量或添加化学外加剂提高混凝土的和易性。过度用水导致出血增加（地表水）和\ /或隔离的总量（当水泥和集料开始分开），由此产生的混凝土具有降低质量。使用的骨料级配不良可能会导致一个非常严厉的设计具有非常低的衰退，不能轻易更加可行的合理数量的增加。
The presence of a pronounced yield point followed by large plastic strains is somewhat unique to steel,
存在明显的屈服点和大的塑性应变是有些独特的钢
