美国爱荷华大学代写论文:混凝土

Keywords:美国爱荷华大学代写论文

混凝土的工作性是新拌混凝土最重要的特性。可加工性可定义为（泰勒，1994），混凝土的性能决定了混凝土的放置、压实和完成的能力。压实是特别重要的，因为它消除空气空隙从混凝土混合。空气空隙对混凝土的强度非常不利。工作性主要受含水率影响。总规模也有影响。较小的聚集体具有较高的比表面积和体积比，需要更多的水来润湿表面。 凝聚力是新混凝土的另一个重要特征。凝聚力（泰勒，1994）可以被定义为新的混凝土抵御离析的能力，虽然一个有凝聚力的组合也将更容易完成，一个相对苛刻的混合。凝聚力是一个具体的混合是由更细的部分沙子和水泥。 新拌混凝土的养护是一个非常重要的步骤，是决定混凝土强度和质量的决定性因素。养护是混凝土的水化过程，一般需要一周左右。它是水饱和混凝土在这个阶段重要的温度也很重要。在5°C以下，混凝土会结冰，混凝土中水的膨胀会给混凝土带来灾难性的破坏。在30°C以上，水会迅速蒸发，导致混凝土结构的凝胶结构降低。

美国爱荷华大学代写论文:混凝土

Workability of concrete is the most important characteristic of fresh concrete. Workability may be defined as (Taylor, 1994) that property of the concrete which determines its ability to be placed, compacted and finished. Compaction is particularly important as it removes air voids from the concrete mix. The air voids are very detrimental to the strength of the concrete. Workability is mostly influenced by water content. The aggregate size also has an impact. Smaller aggregates have higher surface area to volume ratio and need more water to wet the surface.
Cohesion is another important characteristic of fresh concrete. Cohesion (Taylor, 1994) may be defined as the ability of the fresh concrete to resist segregation, though a cohesive mix will also be easier finish that a relatively harsh mix. The cohesion is a concrete mix is provided by the finer fractions of sand and the cement.
Curing of the fresh concrete is a very important step and is determinant in the strength and quality of concrete. Curing is the hydration process on the concrete and can generally take around a week. It is important to saturate the concrete with water during this stage and the temperature is also important. Below 5°c, the concrete will freeze and the expansion of the water in the concrete will be catastrophic to the strength. Above 30°c, the water will evaporate quickly and leads to an inferior gel structure of the concrete mix.

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