Imagine a construction project where stones, sand, and masonry are magically transformed into a solid structure. This transformation is made possible by a fascinating process known as cementitious materials, a combination of physical and chemical reactions. These materials, classified into two categories based on their chemical composition, play a crucial role in construction.
Inorganic cementitious materials commonly used in various mortars can be divided into air-hardening cementitious materials and hydraulic cementitious materials according to their hardening conditions. Air-hardening cementitious materials can only harden in the air, that is, under dry conditions, and can only maintain or continue to develop their strength in the air, such as gypsum and lime. These materials are generally only suitable for use on the ground or in dry environments, not in humid environments, let alone water. Hydraulic cementitious materials can harden better in the air and water, maintaining and continuing to develop their strength, such as various series of cement, which are suitable for above-ground, underground, or underwater projects.
The organic cementitious materials commonly used in various mortars can be divided into natural organic cementitious materials (asphalt) and organic synthetic cementitious materials (synthetic polymers) according to their sources.
Asphalt cementitious materials are mainly used to prepare asphalt floor mortar. They are moisture-proof, waterproof, corrosion-resistant, elastic, tough, and highly strong. Synthetic polymers such as epoxy and unsaturated polyester can be formulated into resin cement and mortar for anti-corrosion floor projects.
Cement is a powdery hydraulic cementitious material mixed with water to form a plastic slurry. It can bind sand, stone, and other appropriate materials. It hardens in the air, humid environment, and water to maintain and increase strength. Cement occupies a prominent and essential position among cementitious materials and is among the most important materials in construction projects.
There are many varieties of cement. According to the names of the leading hydraulic minerals, cement can be divided into several series, such as Portland cement, aluminate cement, sulfoaluminate cement, and so on. The main technical characteristics of cement indicated in its naming can be divided into several subcategories, such as rapid hardening, the heat of hydration, high-temperature resistance, sulfate corrosion resistance, and expansion. Among them, rapid hardening can be further divided into rapid hardening, and There are two categories of ultra-fast hardness:
(1)The heat of hydration can be divided into medium heat and low heat.
(2)The sulfate corrosion resistance can be divided into medium and high sulfate corrosion resistance.
(3)The expansion property can be divided into expansion and self-expansion.
Portland cement series
1. Classification and performance requirements of Portland cement
Portland cement in general cement, ordinary Portland cement (i.e., ordinary cement), slag Portland cement (slag cement), pozzolanic Portland cement (pozzolana cement), fly ash Portland cement (powder Six wide varieties, including coal ash cement), and composite Portland cement, are common varieties in the Portland cement series. Among them, the first five types of cement are commonly used in construction projects and are called the “five major types of cement” in construction projects.
Any hydraulic cementitious material made of Portland cement clinker, 0-5% limestone or granulated blast furnace slag and an appropriate amount of gypsum is called Portland cement (commonly known as Portland cement abroad). Portland cement is divided into two types. The one without admixture is called Type I Portland cement, codenamed P·I. When Portland cement is ground, no more than 5% of limestone or granulated blast furnace slag is added by cement mass. The mixed material is called Type II Portland cement, codenamed P·Ⅱ.
Any hydraulic cementitious material made of Portland cement clinker, 6% to 15% mixed materials, and an appropriate amount of gypsum is called ordinary Portland cement (ordinary cement for short), codenamed P·O. The maximum mixing amount shall not exceed 15% when mixing active materials. It is allowed to use kiln dust that does not exceed 5% of the cement quality or inactive mixed materials that do not exceed 10% of the cement quality. The maximum mixing amount shall not exceed 15% when mixing inactive materials. The amount shall not exceed 10% of the cement quality.
The hydraulic cementitious material made by grinding Portland cement clinker, granulated blast furnace slag and the appropriate amount of gypsum is called slag Portland cement (referred to as slag cement), codenamed P·S.
The cement medium-granulated blast furnace slag dosage is 20% to 70% based on mass fraction. Limestone, kiln dust, fly ash, and pozzolanic mixed materials can be used to replace slag. The replacement quantity shall be at most 8% of the cement mass, and the replaced cement granulated blast furnace slag shall be at least 20%.
Any hydraulic cementitious material made of Portland cement clinker, pozzolanic mixed materials, and an appropriate amount of gypsum ground is called pozzolanic Portland cement, referred to as pozzolanic cement, codenamed P·P. The content of pozzolanic mixed materials in cement is 20% to 50% based on mass fraction.
The hydraulic cementitious material made by grinding Portland cement clinker, fly ash and the appropriate amount of gypsum is called fly ash Portland cement (referred to as fly ash cement), codenamed P·F. The amount of fly ash in cement is 20% to 40% based on mass fraction.
Any hydraulic cementitious material made of Portland cement clinker, two or more specified mixed materials, and an appropriate amount of gypsum is called composite Portland cement (referred to as composite cement), codenamed P·C. The total amount of mixed materials in cement should be more significant than 15% but not more than 50% in terms of mass fraction. Using no more than 8% of kiln dust in cement is allowed to replace part of the mixed materials; when adding slag, the amount of mixed materials must not be repeated with that of slag Portland cement.
