4.9 : セメントのタイプI

Consider a section of a busy highway that is damaged and requires urgent repair to minimize traffic disruption.

Such repair work uses rapid hardening cement, also known as Type III, as it develops its strength quickly.

While constructing large concrete sections, using cement with a high heat of hydration can lead to temperature differences within the concrete mass, leading to thermal cracks in the structure.

As a result, low-heat cement, also known as Type IV, is used as its heat development is the lowest.

Although less C3S, C3A, and lime content in low-heat cement results in lower initial strength; the strength after 90 days is comparable to other cement types.

Consider a concrete sewer pipe; the sulfate ions in sewage can interact with C3A present in the cement in the pipe to produce compounds with increased volume, leading to cracks in the pipe.

Higher exposure to sulfate attack can be resisted using sulfate-resisting cement, also known as Type V, which has less C3A, and for moderate exposure to sulfate ions, modified cement, also known as Type II, can be used.