A type of mixed cement is Portland Pozzolana Cement (PPC). To create the desired pozzolana cement, there are two approaches to produce or blend this cement. The cement particles in Portland Pozzolana Cement are spherical and have a greater fineness value.
Manufacturing
The first technique involves grinding pozzolanic ingredients, gypsum, and ordinary Portland cement clinker in precise ratios. The grinding of pozzolanic, gypsum, and Ordinary Portland cement clinker components while separating and combining them in predetermined ratios is another way.
Pozzolanic material makes up 15–35 percent of it, followed by gypsum at 4% and clinker at the remaining 9–10%.
Concrete moves more easily and has greater fineness because of its spherical shape, which allows for better pore filling. Natural or synthetic materials make up the pozzolanic materials. The primary volcanic-derived materials are the natural pozzolana materials. In addition, synthetic elements including fly ash, burned clays, and shales are used.
This form of cement is increasingly in demand for usage in a variety of construction projects, including multistory tall structures, bridges, dams, and commercial and industrial buildings.
Properties
Calcined clay, often known as fly ash, is one of the primary components used in the production of PPC cement. Fly ash is a waste product produced in thermal power plants when powdered coal is used as fuel. Following that, this material is gathered in electrostatic precipitators. Fly ash and pulverised ash are both referred to as pulverised fuel ash in the United Kingdom, therefore they are interchangeable.
The product, which is also known as calcium silicate, also produces vast amounts of calcium hydroxide, a substance that is largely useless in terms of strength and durability. It is simply a waste of material that could have been used to make cementitious, but it greatly enhances the performance of concrete.
Portland Pozzolana Cement (PPC) has a longer setting time than regular portland cement. It also has a lower initial strength but a much higher ultimate strength. Its initial setting time is half an hour and its final setting time is roughly ten hours.
As is common knowledge, PPC cement takes longer to harden; following initial construction, its compressive strength is 13 MPa after 3 days, 22 MPa after 7 days, and 33 MPa after 22 days. For PPC cement, drying shrinkage shouldn’t be greater than 0.15 percent. For PPC cement, fineness shouldn’t be less than 300 m2/kg.
Although PPC’s end strength is equal to that of OPC cement after 28 days, its initial strength is less.
The forceful attacks of hazardous compounds like carbonate and acid alkalies that are dissolved in water, as well as the prevention of unfavourable climatic circumstances, are two significant characteristics of PPC cement.
Applications
Where OPC is used, PPC cement is used instead, unless a high early strength is a unique necessity. An extended curing period is preferred since PPC use necessitates moisture for continued pozzolanic activity. The following circumstances call for the employment of PPC particularly well for mass concrete dams, bridges, subterranean canals, and other hydraulic structures.
Additionally, marine buildings employ it. PPC increases the density and impermeability of the concrete. Construction of hydraulic structures, marine works, and mass concreting may all be done with confidence using it.