Product Name: Portland Pozzolana Cement Manufacturing Plant
Capacity: 500 – 10000 TPD
Equipment: cement crusher, cyclone preheater, rotary kiln, decomposing furnace, cooler, cement mill, auxiliary equipment, etc.
Cement Manufacturing Plant Features
- CE certificate, high quality guaranteed;
- Low energy consumption and low resource waste rate;
- High production efficiency, maximum capacity can reach 10000 t/d;
- Advanced automatic control system, very convenient to manage your production;
- Low maintenance cost, cost performance is high;
What is Portland Pozzolana Cement?
Portland pozzolana cement (PPC) is a type of eco-friendly cement which is mainly made of ordinary portland cement clinkers and pozzolanic materials (such as fly ash, calcined clay, etc.). Generally, the constituent of pozzolanic materials in Portland pozzolana cement is 10% ~ 25% by mass percentage.
Fly ash is the main ash discharged from the combustion of coal-fired boilers in thermal power plants. It is a kind of mixture of pozzolanic ash with high dispersion. It can react with Ca (OH) 2 in the presence of water to produce calcium silicate, calcium aluminate, and other compounds with hydraulic cementitious properties.
Because using fly ash to make cement can save production costs and avoid polluting the environment, Portland pozzolana cement is becoming more and more popular around the globe.
Portland Pozzolana Cement Manufacturing Process
Just like the manufacturing process of ordinary portland cement (OPC), the portland pozzolana cement manufacturing process includes five main steps: raw material treatment, preheating and pre-homogenization, calcining and burning, cement clinker grinding, and packaging and storage.
In these five steps, the key to make Portland pozzolana cement different from ordinary cement is the fourth step, the cement clinker grinding step. In most PPC manufacturing processes, pozzolanic ashes are added to the cement clinker in the cement grinding step.
There are two ways to manufacture Portland pozzolana cement: 1) Grinding ordinary Portland clinker along with pozzolanic materials and additional gypsum or calcium sulfate; 2) Grinding OPC clinker and pozzolanic materials separately and then mix them together with gypsum. The 1st way is most used in our portland pozzolana manufacturing cement plants.
OPC Clinker and Water react together and Produce C – S – H that gives strength on compaction and drying while making concrete and also liberate lime (Calcium hydroxide).
However, in case of PPC, this free lime is also utilized by making reaction with reactive silica available in fly ash to produce additional C – S – H giving more cement strength value and leading to pore refinement and denser concrete matrix and also leaving no free lime. This action also reduces the liberation of CO2 by decreasing Heat of Hydration process which will ultimately make the environment more green and eco-friendly as compared to OPC.
Portland Pozzolana Cement Features
1. Slow setting and hardening, low early strength and high later strength. The reason is that the clinker content of PPC is small, and the secondary hydration reaction (i.e. the hydration of active mixture) is slow, so the early strength of PPC is low. In the later stage, due to the continuous secondary hydration reaction and the continuous hydration of cement clinker, the hydration products in PPC increases, and its strength can exceed that of OPC of the same grade.
2. Sensitive to temperature and humidity and suitable for high temperature curing. The hydration of PPC at low temperature is slowed down obviously. Curing at high temperature can accelerate the hydration process of PPC, and does not affect the development of strength at the later stage of normal temperature.
3. Good corrosion resistance, which makes it suitable for constructions in erosive environments with sulfates, magnesium, soft water, etc., such as seaports and docks. The corrosion resistance of hydrated and hardened PPC comes from its low proportion of calcium hydroxide and calcium aluminate hydrate.
4. Less hydration heat release; less clinker content in PPC also leads to less hydration heat release, especially in the early stage. Slow heat release rate and less heat release make PPC suitable for mass concrete engineering.
5. Good water retention and low permeability. There are a lot of tiny pores in the mixture of pozzolanic ash, which give PPC the characteristic of good water retention. And the hydrated calcium silicate gel formed after hydration makes the structure of PPC cement paste compact, so the permeability of PPC is low.
According to these features, we could make a conclusion that Portland Pozzolana Cement is suited for the following construction:
- Mass concrete projects;
- Structures with corrosion resistance requirements like marine structures, sewage works, etc;
- Construction under aggressive conditions.
It is not suited for the following construction:
- Projects in dry environments;
- Projects require abrasion resistance;
- Projects require high early strength, such as winter construction, cast-in-place concrete projects, etc.