Ductile iron pipes are widely used in water pipelines due to their high strength, toughness, and excellent durability. To prevent internal corrosion and ensure water quality, they are typically lined with cement mortar (CML). The type of cement used in these linings is crucial, depending on the application environment and performance requirements.
European standard EN 197-1:2011 is the foundational standard for defining and classifying common cements. Portland cement, sulfur-resistant cement, high-alumina cement are commonly used for ductile iron pipe linings. Their key differences lie in their mineral composition, which directly impacts the lining’s ultimate performance. The following details the differences between the three most common cement types:
Portland cement: Any hydraulic binder made from a mixture of calcium silicate-based Portland cement clinker, less than 5% limestone or granulated blast furnace slag, and an appropriate amount of gypsum, is collectively referred to as Portland cement, and internationally as Portland cement.
Portland cement’s characteristics include rapid setting and hardening, high early strength, high heat of hydration, good frost resistance, poor corrosion resistance, low shrinkage during drying, and strong wear resistance. It is suitable for high-strength concrete projects and low-temperature environments, but is not suitable for large-volume concrete or high-temperature, corrosive environments.
Sulfate-Resistant Cement: Sulfate-resistant Portland cement is classified into two categories based on its resistance to sulfate attack: medium-sulfate-resistant Portland cement and high-sulfate-resistant Portland cement. Medium-sulfate-resistant Portland cement is a hydraulic cementing material that is resistant to attack by moderate concentrations of sulfate ions, made by grinding Portland cement clinker with an appropriate composition and adding an appropriate amount of gypsum. This cement is referred to as P·MSR. High-sulfate-resistant Portland cement is a hydraulic cementing material that is resistant to attack by higher concentrations of sulfate ions, made by grinding Portland cement clinker with an appropriate composition and adding an appropriate amount of gypsum. This cement is referred to as P·HSR.
Features of Sulfate-Resistant Cement: Sulfate-resistant cement is a specialty cement designed to resist sulfate attack. It is made from Portland cement clinker with an appropriate amount of gypsum added. Depending on its sulfate resistance, it is suitable for projects exposed to long-term sulfate exposure, such as harbors, water conservancy projects, and underground structures, as well as locations exposed to sulfate-corrosive media, such as chemical plants and sewage treatment plants.
High-alumina cement: High-alumina cement is a hydraulic binder made from calcined and ground clinker primarily composed of calcium aluminate and containing approximately 50% alumina. It is also known as refractory cement or aluminate cement. Its chemical composition primarily consists of aluminum oxide Al₂O₃ and calcium oxide CaO, with small amounts of other oxides such as SiO₂ and Fe₂O₃. The aluminum oxide content is typically over 50%, significantly higher than that of ordinary cement. This high aluminum content gives it a range of remarkable properties.
High-alumina cement’s outstanding properties
- Early Strength: The most notable characteristic of high-alumina cement is its extremely rapid strength development. Within 24 hours of pouring, it can reach over 80% of its final strength. This property makes it ideal for time-sensitive projects such as those requiring rapid demoulding, emergency repairs, and winter construction.
- High-Temperature Resistance: The hydration products of high-alumina cement are relatively stable at high temperatures. When heated, it undergoes a solid-phase reaction, forming new ceramic-like minerals that maintain a certain strength. It is often used as a binder in refractory castables and in the linings of industrial furnaces, and can withstand extremely high ambient temperatures.
- Corrosion Resistance: It is more resistant to chemical attack by sulfates, weak acids, and other chemicals than ordinary Portland cement. This is because its hydration products do not produce calcium hydroxide and calcium aluminate hydrates, which are susceptible to sulfate attack. This makes it valuable for applications in corrosive environments, such as chemical environments, sewers, and marine engineering.
Post time: Sep-17-2025
