What Is The Research In Engineering And Technology ISSN? - A Guide To Concrete Manufacturing And Testing

Raw materials for the manufacturing of concrete

What Is The Research In Engineering And Technology ISSN?

Concrete refers to a toughened material usually made by merging a chemically inert collection (gravel, crushed stones or sand), a binder usually synthetic or natural cement, water, and chemical additives. Most individuals use the term ‘cement' to refer to concrete the term, in fact, it denotes different constituents; Cement usually comprises an extensive different types of fine crushed dusts which toughen the moment they are mixed with water (Amato, 2013). As the concrete hardens up, it obtains a stone-like uniformity which makes it the best construction material for the construction of bridges, roads, sewage systems, waterways, airports, factories, railroad, bulk transit systems, buildings among other structures.

The concrete is usually made up of cement, fine mineral aggregate, course mineral aggregate, in the ratio of 1:2:4. Even though these ratios are habitually diverse depending on flexibility and strength in order achieve desired use of the concrete. Additionally, concrete encompasses a varied variety of chemicals that instill the desired features for the particular use. The Portland cement used is made up of a mixture of a calcareous material mostly aluminum, silica and limestone usually found as shale or clay (Wang, Yang, et al. 2012).

Concrete contains in small amount magnesium and iron oxide. Aggregates comprise 75% of the of the concrete in volume. The aggregates usually improve the flow and the formation of cement paste at the same improves structural performance of concrete. The fine grade is made of constituent part of up to 20mm in size, while the course grade aggregates include particles from 20mm.In the massive construction, aggregate particles sizes can be more than 38millimeters.

The aggregates can also be grouped depending on the rocks which are made up of granite, basalt, and flint among others. Another type of aggregates which are used to make concrete is known as pozzolana, a siliceous and aluminous that forms the calcium silicate hydrates which are the foundation of the cement.

The process of manufacturing concrete is simple. Firstly, the preparation of Portland cement is done. Afterwards, the other constituents of concrete such as aggregates, admixtures any necessary fibers together with water are mixed to create concrete. Then the concrete is dispatched to the site and positioned, compressed and treated (Aïtcin, 2011).

 Silica, limestone and alumina which are the basic constituents of Portland cement are dried on the ground and converted into fine powder, then mixed with set amounts, warmed and heated again to very high temperatures which sets ablaze all the contaminants without necessary blending the ingredients. Thereafter, the mix is burned in a huge rotary (kiln) at a temperature of 2550 degree Fahrenheit. At this temperature, the materials to some extent fuse into the substance usually referred to as clinker. A up-to-date kiln can also produce as much as 6200 tons of clinker per day.

Manufacturing process of concrete

The obtained clinker is cooled and then ground to a fine powder in a ball mill or a tube. Ball mill refers to a strong rotating drum that is full with steel balls of various sizes which grid and crush the clinker. Then Gypsum is supplemented to it during the process of grinding. The last component comprises of quite a number of compounds: calcium silicate, tricalcium silicate, tetra calcium aluminoferrite and tricalcium aluminate (Baeza et al. 2014).

The prepared Portland cement blended with other constituents: admixtures, aggregates, water and fiber. The aggregates are added or pre-blended at the ready-mix concrete plant under ordinary working conditions. Mixing process applies stirring or rotation to cover the superficial of aggregate with cement cream and mix the other components evenly. A range of continuous or batch blenders are applied. Fibers can be added if preferred through a variety of ways such as premixing, direct spraying, impregnating or hand laying up (Li et al. 2011). The silica emission is usually used as a dispersing or densifying agent. The figure below shows the overall concrete manufacturing .

Once the concrete has been transported to the site, it must be placed and compressed. The two operations are done almost at the same time. The placing need to be performed so that the separation of several ingredients is evaded and the filled compaction which is aimed at removing all the air bubbles (Pillar, Woolman and Corp 2010). Whether buggies or chutes are used during this operation, the position is the most important aspect to in achieving this aims. The rates of compaction and placing should be equal to each other, that is achieved by use of external vibrators. Interior vibrator usually uses a poker which houses a motor-driven shaft. The moment the poker is injected into the concrete, regulated vibrations usually arises to compress the concrete to the required levels. The exterior vibrators are usually used for thin in-situ or precast sections having a thickness or shape inappropriate for the internal vibrators. these kind of vibrators have strictly clambered to the formwork.

Once the concrete has been placed on site, the concrete must be cured to ensure that it does not harden quickly before it is finished. The strength of concrete is usually affected by the amount of moisture available during the drying procedure. As the cement hardens, the concrete contracts. If site restrictions stop the concrete from shrinking the tensile stress will be crated, and thus waning the concrete (Kuma, Srikanth and Rao 2012).

Preparation of Portland cement

Site/ Laboratory testing techniques to verify the quality and conformance

Both laboratory and site tests on concrete are very significant to assess the consistency, durability and mechanical strength of the concrete. The tests are related to the concrete both in the hardened and fresh state. The durability of concrete and the methodology on how the tests were to be carried out are specified respectively, in varicose standards, specifications, test procedures and in other approved documents (Bungey and Grantham 2014).

To carry out the tests on fresh concrete is to establish some essential properties to ensure proper application of the concrete on sites, such as workability, consistency, density and air content of the fresh concrete. The tests which are carried out on the fresh concrete ensure proper fluidity without the separation of the various constituents' materials and to establish parameters which are premonitory on the quality of the same after hardening concrete (Bartos, 2013).

The tests which are carried out on the hardened concrete are aimed at the behavior the concrete will have on the service condition, for instance when the concrete is to perform the function they were designed for. The tests on the hardened concrete are divided into physical and mechanical tests by taking into account the general properties that are required for the concrete (Kovler and Roussel 2011).

Both the physical and mechanical tests are aimed at determining the structural characteristics of the materials that are used and at the same time to analyze the structural behavior of the concrete. The table below shows the tests carried out on hardened concrete.

There are many factors which contribute to the degradation of concrete such as corrosion of the reinforcement which might be induced by the chlorides and carbonation; thawing/action of freezing and the chemical attack. The mentioned factors can also contribute to the deterioration of the durability and capacity of structures. The durability testing usually establishes the characteristics of the materials and structures. Durability determines the characteristics of the material and the structure which might cause malfunctioning in the long term. The table below shows the tests carried out for durability (Pleau and Pigeon 2014).

The use of concrete in the construction of commercial projects has many advantages and disadvantages as discussed below.

• The ingredients of concrete are readily available in most areas.
• Unlike other building materials concrete is free from flaws and defects.
• Concrete can be manufactured with varied strength or other qualities depending on the use.
• Concrete has a very high durability
• With the use of solid work, the concrete can be cast into any shape.
• The casting of concrete can be done in the working place which makes it very economical
• Concrete has very low maintenance costs. Concrete has the ability to withstand high temperatures
• Concrete is usually resistant to water and wind. With that, it can be used for the construction of the commercial project in storm-prone areas (Pacheco and Jalali 2011).

Even though concrete has many advantages when used in construction there are many setbacks also associated with the use of concrete some of them include;

Concrete is usually less ductile

The weight of concrete is very high compared to its strength.

The constituents of concrete can contain soluble salts which may cause efflorescence

Compared to other construction materials, the tensile strength of concrete is very low (Thorpe and Zhuge 2010).

evaluating the use of proper references and citations for the report/presentation

It is very essential to cite the sources used in the report or the presentation because;

• The proper referencing and citation shows the reader that there was proper research which was done by listing all the sources that were used to obtain the data
• Proper referencing and citation make the researchers be responsible scholars by giving credit to other scholars and researchers and at the same time acknowledge their ideas.
• Referencing and in-text citation helps to reduce the plagiarism by quoting directly where the data was obtained from.
• Proper referencing and citation help the reader to track down the sources that were used by the use of footnotes and reference list or bibliography (Lewis, 2015).

References

Aïtcin, P.C., 2011. High performance concrete. CRC press.

Baeza-Brotons, F., Garcés, P., Payá, J. and Saval, J.M., 2014. Portland cement systems with the addition of sewage sludge ash. Application in concretes for the manufacture of blocks. Journal of Cleaner Production, 82, pp.112-124.

Bartos, P., 2013. Fresh concrete: properties and tests (Vol. 38). Elsevier.

Bungey, J.H. and Grantham, M.G., 2014. Testing of concrete in structures. Crc Press.

Kovler, K. and Roussel, N., 2011. Properties of fresh and hardened concrete. Cement and Concrete Research, 41(7), pp.775-792.

Kumar, M.J., Srikanth, M. and Rao, K.J., 2012. Strength characteristics of self-curing concrete. International Journal of Research in Engineering and Technology ISSN, pp.2319-1163.

Lewis, S., 2015. Qualitative inquiry and research design: Choosing among five approaches. Health promotion practice, 16(4), pp.473-475.

Li, W., Xiao, J., Sun, Z., Kawashima, S. and Shah, S.P., 2012. Interfacial transition zones in recycled aggregate concrete with different mixing approaches. Construction and Building Materials, 35, pp.1045-1055.

Pacheco-Torgal, F. and Jalali, S., 2011. Nanotechnology: advantages and drawbacks in the field of construction and building materials. Construction and Building Materials, 25(2), pp.582-590

Pleau, R. and Pigeon, M., 2014. Durability of concrete in cold climates. CRC Press.

Pillar, D.R., and Woolman, W.M., Oshkosh Corp, 2010. Concrete placement vehicle