Courtesy of the global warming issues – the concerns over the anthropogenic carbon emission on global climate have enhanced rapidly. At the same time, the IPCC report specifically focuses on limiting the temperature to 1.5-degree Celsius. It is no secret that cement production produces tons of kiln dust – contributing to the environment-generated hazards. However, what is notable is – the production of white portland cement (used specifically for architectural purposes) accounts for somewhere around 5% of anthropogenic carbon emissions.
Surprised? Well, a study made by the University of Bath states that – cement has comparatively lower embodied energy per pound in comparison to other building materials. Therefore – when you talk of portland cement – it is a rather ‘environment-friendly’ material in regard to its counterparts.
The history of Portland Cement
For the uninitiated – portland cement – is definitely, one of the best inventions required in the modern nature-friendly world. Both – invented and patented by Joseph Aspdin and James Parker back in 1824 – were curated simply by – concocting clay with the powdered form of limestone and heating it over a furnace. After the heating process, a clinker was formed where – upto 3% of gypsum was added, and the mixture was grounded.
So why the name Portland? Well – after it was created – the hue it obtained was quite similar to the limestone quarried near the Portland channel (known as Portland stone). Hence – the name – portland cement. At a later stage – Aspdin’s son – William, started producing it commercially and therefore is referred to as – the initial modern producer of portland cement.
Speaking of the white portland type that seems to be ‘in demand currently’ – it is a specific type that is used for decorative purposes (its milk-white shade winning points).
However – have you thought as to why this form of cement has garnered such immense popularity vis-a-vis its counterparts? Apart from the fact that it is available in almost five types – one must also note its triad of qualities that includes – adhesiveness, hydraulic nature, and its noise-insulation benefit.
So, what is it composed of? The next section will provide you with the answers -
Chemical Composition of Portland Cement
Speaking in pure chemical terminology – the portland cement is composed of – calcium silicate (both the double and triple chemical value of the component), tetra-calcium alumino-ferrite, and tricalcium aluminate. Apart from these primary components, there are traces of magnesia, other elements(iron and alumina), alkalies, and uncompounded lime.
Manufacturing of Portland Cement
As you already know that the manufacturing procedure of portland cement (the basic remains the same – the changes happen to post the basic procedure according to the varieties) is divided into certain stages. To understand briefly – once the raw materials are obtained, they are classified and homogenized. Next is the clinkerization process, which results in the cooling and further milling. Quite confused? Scroll down to comprehend in a better manner -
Generally speaking – cement is prepared by both the dry and the wet procedure. Though most of the manufacturers prefer the dry format, the details of which will be elaborated on below in the article – it is time to get a brief idea about the wet process.
In the wet process – it so happens that the raw materials that are there are grounded in water and then fed into the kiln. In this case – the fuel consumption is comparatively more, and so are the environmental effects – the handful of reasons for makers to use the dry procedure.
As far as the dry process is concerned -
#Step 1 – The Crushing and Grinding aspect
Given that clay and limestone are the primary materials used – keep them between 5-10mm, and while they are crushed and later joined together – the size should not be more than 0.5mm (fine form).
#Step 2 – The proportion of raw material
To create what is called the raw feed – the proportions of the concerned raw materials are taken as per notification.
#Step 3 – Heating of the raw feed
The raw feed that has been obtained from the second step is put into a conveyor and heated up to 1400-1500 degree Celsius to create the concoction – ‘clinker’. Note this well – the size of these granules is within 1-3 cm in diameter.
#Step 4 – Formation of the clinker
As you can see, a red-hued mixture has been discharged from the kiln – it is officially called ‘clinker’, and after cooling, further procedure is carried out.
#Final Step – Adding the gypsum
When the cement clinker is ground – a quantity of (around 3-5% as per requirement) gypsum is added to that to ensure that while combining the mix with water, the settling features of concrete gets controlled. After that – it is mixed with plaster to create the currently famed – Portland Cement.
#Now that you have a fair idea regarding the manufacturing procedure of portland cement – how about getting a bit concerned about the variations available in the portland type? For starters
The white portland type is specifically curated to be used for architectural purposes where there is a requirement for white concrete, and it is the restricted usage of ferrite (reason for the grey color of the cement) is why the color is milk-white.
The hydration portland cement of the low-heat type is developed at a comparatively slower strength rate than its counterparts.
The sulfate-resisting portland type is particularly curated to ensure the sulfate content (which causes cracks in the concrete) has restricted access to this form of cement.
Finally, the rapid-hardening portland type ensures that the fine particles into which this has been grounded rapidly react with water compared to the other varieties of portland cement.
The portland cement variety has been one of the recent invaluable inventions that has revolutionized the construction industry. The dominance it has garnered due to its strength and hydraulic properties is in addition to its improved technical quality. Clearly, here is a block of cement that commits to caring.
Optimistically – this article has helped you comprehend some specific details regarding the portland type and its extended white portland cement. In that case, make a well-informed decision, keep the health and social concerns in mind, and choose one for the construction process.