An Experimental Study On The Effectiveness Of Using Admixtures In Concrete Compared To Traditional Mix Materials; Ultimately Impacting Workability And Compressive Strength

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Contextual Background

Concrete admixtures enhance the performance of concrete by increasing workability or reducing the water content, accelerating or diminishing the hardening time, strengthening and improving resistance to chemical attacks and different weather conditions (Jamal, 2017).

There are many types of admixtures; some of them are as follows; Water reducing admixtures, retarding admixtures, accelerating admixtures, pozzolanic admixtures and various others (Anupoju, 2019). This project studies the effectiveness of admixtures being used in concrete rather than the traditional mix, which will ultimately impact the workability and strength of structures.

Research Aim

An investigation on the use of concrete admixtures and their impact on concrete strength and workability in the construction industry.

Research Objectives

1. Study the damages associated with concrete on structures without admixtures due to its slow setting nature.
2. Study of admixtures and their uses in the construction industry. O hydration process and chemical reaction between admixtures and cement. O improving the rate of hardening without compromising the concrete strength.
3. Experimental investigation and analysis of mix designs with and without admixtures testing compressive strength and workability.
4. Evaluate the feasibility of admixtures in the modern-day construction industry

Problem Statement

This research will focus on the effectiveness of using admixture in concrete compared to traditional mixes by experimenting with different mixes and studying the impact of their effectiveness in terms of strength and workability.

Traditional concrete consists of water, air, cement and a mixture of gravel, sand and stone (Faris, 2016). Adding the right quantity of these materials will result in the concrete having higher strength. Adding the right proportions of these materials can be tricky and have lower strength than admixture cement.

If too much cement paste is added, then it will be easier to pour but will crack more easily. Consequently, rough and porous concrete will form as a result of a low cement past (Darling, 2019). Studies in the past merely focused on testing the traditional cement mixtures without finding alternate ways to improve the durability of cement altogether.

Additionally, the limited number of studies focusing on admixture contemplate upon it from a theoretical perspective without articulating the results with any subjective or primary findings. Thus, the following study intends to fill in the literature above the gap.

Rationale and Significance

Admixtures allow for the concrete to have different properties than the traditional mix and can be used in emergencies if any problems arise during construction. The use of traditional mix in concrete can create certain problems, which would result in having low strength of the structure being built.

One problem can be; having trapped air bubbles in a traditional concrete mix. This happens because stiff cement paste does not allow the air to escape, and fine sand and aggregates trap the air bubbles within, resulting in a weak concrete structure (CCI, 2019).

The significance of this is experimental study is that it would allow future engineering researchers to have an idea of the impact of effectiveness in using admixtures in concrete rather than traditional mix.

Admixtures are used in construction because it allows to change the properties of concrete and enable it to have increased workability, time of initial setting is accelerated or retarded, improve pump ability and reduce segregation. It is also used to achieve desired effects more economically because different effects cannot be produced using the traditional mix (Mishra, 2019).

Literature Review

Since different types of admixtures are used to improve the properties of concrete for construction, they allow the manufacture and construction of special concrete which has high fluidity and high strength and can be used underwater and can also be sprayed on different materials.

Using admixtures, it became possible to create an ultra-high-strength concrete with a compressive strength value of more than 150 MPa and manufacture a self-compacting concrete that does not require compaction (Plank et al., 2015).

High-strength concrete has been researched since the 1980s, and due to this research, it made possible the development of Reactive Powder Concrete (RPC). The components of RPC include active components such as ground granulated blast furnace, silica fumes and cement.

These components replace the traditional coarse aggregates and allow to have a compressive strength greater than 200 MPa. Nonetheless, with rapid development in the construction industry, the compressive quality of concrete also developed, allowing the manufacturing of Ultra-High Performance Concrete (UHPC) and Ultra-High Performance Fibre Reinforced Concrete (UHPFRC) (Yu, Spiesz and Brouwers, 2015).

 

Methodology

To determine the consistency of the concrete mix, a concrete slump or slump cone test is used either in laboratories or at construction sites. This test is carried out in batches to ensure a uniformness of concrete during construction.

This test is carried out per the given procedures in ASTM C143 in the US, IS; 1199-1959 India and EN 12350-2 in Europe (Mishra, 2019). Some of the factors that affect concrete slump tests are; chemical admixtures, properties of materials used, air content, temperature, and others (Mishra, 2019).

Gantt chart

References

Anupoju, S. (2019). 15 Types of Admixtures Used in Concrete. [online] The Constructor. Available at: https://theconstructor.org/concrete/types-concrete-admixtures/5558/ [Accessed 28 Oct. 2019].

CCI (2019). 6 problems with concrete countertop mix designs and how to prevent them – Concrete Countertop Institute. [online] Concrete Countertop Institute. Available at: https://concretecountertopinstitute.com/free-training/6-problems-with-concrete-countertop-mix-designs-and-how-to-prevent-them/ [Accessed 28 Oct. 2019].

Darling, D. (2019). Everything You Need to Know About Concrete Strength | Cor-Tuf. [online] Cor Tuf. Available at: https://cor-tuf.com/everything-you-need-to-know-about-concrete-strength/ [Accessed 28 Oct. 2019].

Faris, D. (2016). It’s Everywhere, but What Exactly Is Concrete?. [online] ZME Science. Available at: https://www.zmescience.com/research/materials/its-everywhere-but-what-exactly-is-concrete/ [Accessed 28 Oct. 2019].

Jamal, H. (2017). Types of Admixtures of Concrete & Cement | Chemical, Mineral. [online] Aboutcivil.org. Available at: https://www.aboutcivil.org/concrete-technology-admixtures.html [Accessed 28 Oct. 2019].

Mishra, G. (2019). Concrete Admixtures (Additives)- Types, Selection, Properties, Uses. [online] The Constructor. Available at: https://theconstructor.org/concrete/concrete-admixtures-types-and-uses/409/ [Accessed 28 Oct. 2019].

Mishra, G. (2019). Concrete Slump Test for Workability -Procedure and Results. [online] The Constructor. Available at: https://theconstructor.org/concrete/concrete-slump-test/1558/ [Accessed 28 Oct. 2019].

Plank, J. et al., (2015). Chemical admixtures — Chemistry, applications and their impact on concrete microstructure and durability. Cement and Concrete Research, 78, 81–99. doi:10.1016/j.cemconres.2015.05.016

Yu, R., Spiesz, P., & Brouwers, H. J. H. (2015). Developing an eco-friendly Ultra-High Performance Concrete (UHPC) with efficient cement and mineral admixtures uses. Cement and Concrete Composites, 55, 383–394. doi:10.1016/j.cemconcomp.2014.09.024