THE DEVELOPMENT OF CONCRETE AS CONSTRUCTION MATERIALS
Author: Pichaya Techakijkriangkrai, University of Bristol, Bristol, U.K.
Personal Tutor: Dr. Theo Tryfonas, University of Bristol, Bristol, U.K.
ABSTRACT: This report contains information about the historical development, properties and usages of the concrete as the main materials used in construction nowadays. It is focused on three main properties which are strength, elasticity and durability. This It also includes the example of the usage of concrete, the road construction. It is hoped that this paper can be used and reviewed by other civil engineers.
KEYWORDS: concrete, strength, elasticity, durability, civil engineering.
1. INTRODUCTION
In the modern days, the most common materials used in construction is concrete as it is a versatile material with properties like high compressive strength relative to its tensile strength. Its unique adhesive and cohesive properties allow concrete to easily be molded into shaped. It is also water resistant and is low in price relatively to other materials. (J. M. Monteiro and Kumar Mehta, 1986, P 7-8)
Concrete is made by mixing water with aggregate and cement in a correct ratio. (A M Neville, 1987, P xii). Concrete are applied to the modern society as glue to the infrastructure. Civil Engineers use concrete to produce numerous amount of infrastructures ranges from roads, skyscrapers to dams.
The purpose of this essay is to explore the historical development, properties and the application of the concrete as a construction material in Civil Engineering.
2. HISTORICAL DEVELOPMENT
Concrete was first developed in 3000BC by Egyptians. They used the mortar made of calcined impure gypsum and lime to build pyramids.
Between 3000 BC and 470 AD, the Romans used the calcined limestone, brick, lime and water to produce a foremost concrete. They constructed a great masonry such as the Colosseum and the Pantheon. The volcanic ash is also added to the mixture to allow the concrete to set underwater. (Wikipedia)
In eighteenth century, the concrete industry advanced due to the demand for the lighthouse in England in order to prevent the loss of ships. The first lighthouse, Smearton, was built using a combination of the pozzolona cement and the limestone which contain high proportion of the clay giving it a hydraulic property. (A M Neville, 1987, P1)
In 1824, Joseph Aspdin, invented the ‘Portland Cement’ which is made by mixing clay and hard limestone in a furnace blast with carbon dioxide at a clinkering temperature until it clinkers. This Portland Cement is altered by Isaac Johnson in 1845 to mass produced the cement used today. (A M Neville, 1987, P2) In 1854, Williams Wilkinson, came up with an idea to reinforce steel into the concrete increasing the overall tensile strength.
In 1930, Yoshida has pioneered the Ultra high strength concrete which is the concrete that can withstand the earthquake wave. This improves the engineering industry as the thinnest concrete could improves the durability, improve impermeability against corrosion which translates to reduce maintenance and longer life span for the structure.
3. PROPERTIES
3.1 Mechanical Properties
3.1.1 Strength
Strength of the concrete is described by the maximum stress it can withstand before the failure. Failure varies with the investigations; compressive strength failure happens when internal structure could not carry load any longer while the tensile strength testing shows that failure exist as a fracture. (J. M. Monteiro and Kumar Mehta, 1986, P 50)
Concrete is a material with high compressive strength meaning that it usually reinforces with the steel to increase the tensile stressed in the particular area of the concrete to avoid failure. Compressive strength is widely used as the universal general index of the concrete. There are two main factors that can affect the strength of concrete. This is mainly to do with the void which present at the stage of hydration and the water/cement ratio. (A M Neville, 1987, P268) This is because both factors have an effect on the cement mortar matrix and the interfacial transition zone between matrix and the course aggregate. (J. M. Monteiro and Kumar Mehta, 1986, P 53).
Firstly, the porosity of the cement can alter the strength of the cement. However, this varies with the type of aggregates used. The relative strength of the plaster of paris concrete is inversely proportional to the percentage of the porosity of it. Thus, the relative strength of it is directly proportional to the log of the percentage of the porosity of it. The greater the proportion of the cement compared to water,
Secondly, the water-cement ratio. This allows the cement to hydrate to prevent cracked which happens when the water content is too low. It also prevents the ‘thermal cracking’ which occurs when concrete undergoes the cooling process. Despite the water-cement ratio, concrete is normally achieved within 28 days after mixing.
The Fig.1 shows the relative gain of strength with time of concretes with different water-cement ratios, made with Portland cement.
The Fig.2 shows that the greater the water-cement ratio, the lower the compressive strength.
The higher water-cement ratio the lower the compressive strength because the
Both water-cement ratio and the porosity affect the volume of the concrete
3.1.2 Elasticity
Elasticity of the concrete defines its stiffness. The stress-strain graph shows that concrete is not an elastic material. This is because the concrete behaviour which can be shown in the Fig.3.
Fig.3 Shows the stress-strain behavior of concrete under uniaxial compression.
Elasticity of the concrete is divided into four main regions. (1) Below 30 percent of the ultimate load, concrete exhibits an elastic behavior at the lower end while the interfacial zone remains stable. (2) Around 50 percent of its ultimate stress, the concrete begins to have longer cracks because greater strain is applied. (3) About 50 to 60 percent onwards, the cracked can easily be present at the higher end of the ultimate load. (4) At about 75 percent of the ultimate stress, the load reached its critical point and there are spontaneous growth of the crack. Thus, we have to look at the stress and strain graph to decide whether concrete is suitable for the construction of certain infrastructure. (J. M. Monteiro and Kumar Mehta, 1986, P 88-89)
The elastic modulus of the hardened paste is about 10-30 GPa and aggregates about 45 to 85 GPa. The concrete composite is then in the range of 30 to 50 GPa. (Wikipedia). The Poisson’s ration of the concrete is about 0.2 which does not have an effect on the concrete properties such as the water-cement ratio and the curing age ratio.
3.1.3 Durability
Durability of the concrete is the ability to resist corrosion, chemical attack and abrasion. Concrete is durable and it is suitable as
4. APPLICATION TO THE DAILY LIFE
The concrete is used in the construction of many infrastructures. One of its function is to be used in the asphalt road construction. The concrete mixture consists of the aggregates, chemicals and a small amount of water (about 0.35 to 0.4 water-cement ratio). As a result, a concrete has a strength up to 35MPa, void content of 15-35%. It is good as the porous structure allows the water to flow through below the road. Moreover, it is water resistant which support the pavement as well as the storage the the drainage of water surface. Moreover, it is durable and can withstand heavy loads. Surfaces made of actual Portland cement can be divided into several categories based on the type of joint method to prevent cracking of the road surfaces. In comparison to other types of concrete, the road made of cement is more durable than asphalt ones. However, the concrete road is more expensive and
5. CONCLUSION
Concrete is a versatile material which is mainly used in the construction due to its high compressive strength. Despite the low tensile and flexural strength. Therefore, Civil engineers often chose this as a materials when they are choosing to construct an infrastructure ranges from small like to the large structure like the stability
References
Concretenetwork.com. (2017). History of Concrete – Concrete and Cement History Timeline – The Concrete Network. [online] Available at: https://www.concretenetwork.com/concrete-history/ [Accessed 6 Nov. 2017].
En.wikipedia.org. (2017). Concrete. [online] Available at: https://en.wikipedia.org/wiki/Concrete [Accessed 6 Nov. 2017].
Mehta, P. and Monteiro, P. (2006). Concrete. 3rd ed. New York, NY [u.a.]: McGraw-Hill Education, p.(7,8,50,53).
Understanding-cement.com. (2017). History of cement. [online] Available at: https://www.understanding-cement.com/history.html# [Accessed 6 Nov. 2017].
http://www.hcia.gr/en/cement-concrete/uses-concrete/paron_skurodema_odopoiia/ accessed 18/11/17
http://www.rsc.org/images/Construction_tcm18-114530.pdf accessed 18/11/17
http://www.cement.org/learn/concrete-technology/concrete-design-production/ultra-high-performance-concrete https://en.wikipedia.org/wiki/Properties_of_concrete
http://www.hcia.gr/en/cement-concrete/uses-concrete/paron_skurodema_odopoiia/
Fig. 1 is taken from the book
Fig. 2 is taken from the book
Fig. 3 is taken from the book called Concrete Microstructure, Properties, and Materials by P. Kumar Mehta and Paulo J.M. Monteiro p 88