Cement, no doubt, is the most essential component of almost all constructional materials. It is applied in nearly all stages of all construction processes. From the stabilization of the soil for foundation formation at the sub-structure level (below the ground) level to erecting the super-structure (above ground level), Cement is applied in quite ample quantity all the way. It's ability to bind aggregates together to produce either mortal or concrete makes it an indispensable material in construction. As a matter of fact, whomever claimed that cements hold buildings in place is not far from truth. Our present method of construction is, in fact, based upon our reliance on the amazing and non-disputable binding ability of cement, especially of our modern day cement.

True as it is, cement has always find its use in constructional operations even in remote times - as far back as the twelveth century - though its earliest occurrence was claimed to been abouttwelve million years ago as a deposits. Well, you do not need to ponder if the form of cement found at that time is the same we make use of today- let me help you on that. Yes. However, the earliest known form of binder utilised by the early Roman and Macedonian builders is not the same as we have today. In fact, in construction, the term "binder" would best describe the essential material that our present day cement has come to prove as the most effective; materials that have the ability to glue or bind other materials, and in this case Sand. Binders would come in so many forms and compositions.

The earlier builders would actually utilize Lime (Calcium Oxide) as their choice binder for their structures. In fact, this material is a suitable choice for these builder that when mixed with powder formed from crushed volcanic tuff (a type of volcanic rock formed from the volcanic ash discharged during volcanic eruption), it would produce a mixture that can set (harden) under water. This, of course, would later enable them to use it for the construction of harbors and canals.

Lime found general acceptance as a choice binder until about the 16th century when another form of binder found its way to the construction scene. Tabby, such is the name of the new binder, was made entirely from oyster shells and water. Its production, quite labor-intensive, however proved to be worth it at the time of its adoption. It was produced from oyster shells crushed and burnt into quicklime which is then hydrated (slaked) and then mixed with sand, water and more shells. The resulting product is either poured in a mold to form bricks, which are used for construction, or utilized like present day concrete.

All this binding materials, however, have a common fault. They take longer time to set (to harden). This doesn't seem to pose a significant problem at first. But you know, as it's always with human, our "Oliver-Twist's" tendencies began to set it. We seem to demand more from binders. And our "Oliver Twist" personality emerged in the person of John Smeaton. Mr. Smeaton was an engineer and was in charge of the construction of the Eddystone Lighthouse, now referred to as The Smeaton's Tower. The light house was to occur in the English channel, a water body that seperates the southern England from northern France.

Here, he had a problem. The problem is with the setting time of the binders in existence at that time. These binders would take so much time to set that the coming high tides, occasional of the english water, wouldn't have a hard time sweeping a whole day's work along with it. This is quite a problem, one he was ready to conquer. Thus, he began to experiment with various forms of possible binding materials. Well, let your guess be as good as mine, he eventually stumbled upon one which actually paved way to the binder (cement) we have come to be very much familiar with this present day.

John Smeaton, while mixing different limestones with additives such as pozzolans (i.e clay), discovered that the setting ability of these samples are directly related to the clay content oof the limestone. What this simply mean is that they lime mixture tends to dry faster as their clay content increases. The basis of the production process of the commonly used present-day cement, portland cement. Portland cement is manufactured from the mixture of limestone, clay (or other pozzolanic materials) and several other additives.

Enough of the history, let's fast-forward to the discussion of the day and what exactly is meant by Bio Cement. No doubt, the production and usage of our present day Portland Cement pose dangers and threats to our environment, with the majority of the dangers emerging from the emission of Carbon (IV) Oxide into atmosphere during the heating of limestone in the production stage. It is said that this stage alone produces about 10% of the man-made global emission of this greenhouse gas, Carbon (IV) oxide. It is estimated that over 900kg of Carbon (IV) Oxide discharged for every 1000kg of Portland Cement produced. In addition to the release of Carbon (IV) Oxide, Heavy metals such as thalium, mercury, cadmium, and traces of metal sulfides, zinc blende and galena are also emitted into the atmosphere. Endangering lives, both humans’, plants’ and animals’, as a result. Apparently, cement, though an essential ingredient of concrete, is anot an eco-friendly constructional material.

It is estimated that 4100 million metric tonnes were produced globally, as at 2017 - quite a staggering amount of cement that is. This literally means that about 3690 million metric tonnes of Carbon (IV) Oxide was released into the atmosphere in 2017 from the production of cement alone. You will reckon that this is bad. Bad for every one. Its production, however, never ceases. And with a staggering rise in construction as at January 2018, cement production is expected to be on the increase.

So, What is this exposition all about?

Having established how much damage the production and use of cement of cement are causing to the environment, yet how much indispensable they are to the development of the modern world, it is quite essential that an alternative to this essential element of concrete be sort for. This, as a matter of fact, is the spirit behind this write up.
Well, first off, I am very glad to inform you about a bio-cement.

You heard right. Bio-Cement.

Bio-Cement

No doubt, technological development is on the rise daily. I really doubt if a regular tech user like myself can really keep with its development rate. It is daily on the rise and its impact is being felt in every aspect of the industries. Sustainable engineering necessitate technology development relating to construction materials, their production and manner of use. The proof of the participation of micro-organisms in the carbonate precipitation has guided researchers into probing the possibility of developing a bio-tech process into the production of cement and other construction material.

Microbial Induced Carbonation Procipitation (MICP) is the introduction of ureolytic bacteria.the precipitation process. A process whereby atmospheric Carbon (IV) Oxide combines with water at the time of rainfall to produce Carbonic Acid which impusively disassociate into hydrogen ions and bicarbonate. Dissolved Carbonate combines with dissolved Calcium to produce Calcium Carbonate. The Calcium Carbonate later crystallises into Calcite and Aragonite which are the core components of Limestone, a raw material for the production of cement. All these happen in the presence of the bacterial.

What results from the above process is called Bio-Cement.

The following, however, are the advantages of Bio-Cements over Ordinary Cements.

1. Bio-cement requires a shorter time and lower temperature for production than ordinary cement needs.
2. In-situ (or on-site) raw material of bio-cement are produced at very low temperature and energy, and emits lower carbon (IV) oxide and no hazardous environmental unlike Lime stone quarrying activity employed for the production of ordinary cement.
3. The compressive strength of mortal produced with Bio-Cement is increased by 38%.
4. Bio-Cements have the ability to remediate cracks in concrete structures and regain its original strength within a period of 28days (self-healing)
5. Microbial cells used for the production of bio-cements can be produced using industrial by-products such as corn sheep liquor and lactose mother liquor.
6. Concrete structure’s life are increased while the bricks durability an strength are increased too.

Conclusion

No doubt, cement remain one of the essential ingredient of concrete, a useful material in the construction industry. The production and use of cement releases harmful gasses into the atmosphere and also uses more energy particularly during production. Bio-Cement is the production of cement using a microbial induced process. This process reduces the need for energy for production and the emission of harmful gasses during production, and yet producing a more stronger product (concrete) than normal cement would. In addition, it has a self-healing ability. This means that a crack surfacing in a concrete made with bio-cement will seal up itself and retains its original strength, all In 28days. Bio-cement, definitely, is a necessity for future construction particularly for sustainable engineering and for environmental consideration.

I hope you learn one or two things today. Thank you once more for dropping by, and stay tuned for more of modern civil practices.