SCHOOL OF ARCHITECTURE, BUILDING AND DESIGNBACHELOR OF QUANTITY SURVEYING (HONOURS)

Research on Building Material - CONCRETE

Kevin Lee Hee Xian 0315192

Jake Sia Chyi Sern 0314396

Melvin Lim Wei Jien 0315772

Voon Sze Lun 0315032

Table of Content

Introduction

Concrete Degradation and Defects:

2.1 Deformation of the surface

2.2 Cracking of the surface

2.3 Disintegration of the surface

2.4 Other defects

Environmental Impact of Concrete:

3.1 Carbon dioxide emissions and climate change

3.2 Raw material used

3.3 Water wastage

3.4 Water pollution

3.5 Energy

3.6 Health concern

Conclusion

Reference

Introduction

There are many concrete defects that usually occur during construction. These defects

are broken down into four groups based on observation: deformation of the surface,

cracking of the surface, disintegration of the surface and other defects.

DEFORMATION OF THE SURFACE

Deformation of concrete surface can occur in 3 different ways:

Curling

Causes: moisture in the concrete.

Location: edges and corners.

Warping

Causes: temperature change in the concrete.

Location: edges and corners.

Blistering

Causes: delamination of surface mortar

Location: at the surface of the concrete where mortar is laid.

CRACKING OF THE SURFACE

Cracking of the surface of concrete can occur in many ways. A few of which are most

common are these 4 different cracks:

Plastic Shrinkage

Cracks that are parallel to the concrete slab.

Causes: shrinkage of the concrete that take place when the concrete is still fresh

Crazing

Cracks that seem like random fissures

Causes: rapid evaporation of moisture from the concrete surface

Map-cracking

Random fissures however bigger than crazing

Causes: alkali-silica reaction in the concrete.

Structural failure cracking

Has no specific crack

Causes: change in elevation.

DISINTEGRATION OF THE SURFACE

Disintegration comes in 3 different type of distress:

Dusting

Causes: saturation of carbon dioxide during finishing making a weak layer of cement on

the surface of concrete.

Ravelling or Spalling

Causes: dislocation of pieces of concrete at the joint edges.

Flaking

Causes: blistering which is the breaking of pieces from the surface of the concrete.

OTHER DEFECTS

These defects are caused by the mortar not filling the spaces between the aggregate

particles.

Bugholes

Small voids in the surface of vertical concrete placements.

Honeycombing

Large voids in the surface of vertical concrete placements.

Environmental Impacts of Concrete

1. Carbon dioxide emissions and climate change - The cement industry is one of two primary industrial producers of carbon dioxide,

creating up to 5% of worldwide man-made emissions of this gas, of which 50% is from the chemical process and 40% from burning fuel.

- Cement manufacture contributes greenhouse gases both directly through the production of carbon dioxide when calcium carbonate is thermally decomposed, producing lime and carbon dioxide, and also through the use of energy, particularly from the combustion of fossil fuels.

2. Raw material used - Concrete is made from raw material such as limestone, marl and chalk. These are the

most common sources of calcium in the cement. All these raw materials comes from mining, and mining will affect the echo system as lots of deforestation, water catchment, water natural flow is disturbed.

3. Water wastage - Few billion tons of water has wasted just because of the making of concrete, as

because water is one of the main sources in making concrete.

4. Water Pollution - Another environmental issue with cement and concrete production is water pollution. - At the batch plant, wash water from equipment cleaning is often discharged into

setting ponds where the solids can settled out.- Some returned concrete also gets put into settling ponds to wash off and recover the

aggregate.

5. Energy - Energy consumption is the biggest environmental concern with cement

and concrete production. Cement production is one of the most energy intensive of all industrial manufacturing process.

- Including direct fuel use for mining and transporting raw materials, cement production takes about 1,758 kWh for every ton of cement.

6. Health concerns - The presence of some substances in concrete, including useful and unwanted

additives, can cause health concerns.- Working with wet concrete requires a number of precautions, primarily to protect the

skin from the high alkalinity that can cause chemical burn.

Conclusion

Although concrete is vital and important for construction especially in a developing country like ours, in order to help reduce or stop the environmental impacts of concrete, we should also try to reduce the amount of concrete usage by using alternative types of concrete such as fly ash.

Refrences

1. Cement.org.Evaluating Concrete DefectsIn-text: (Cement.org, 2014)Bibliography: Cement.org. (2014). Evaluating Concrete Defects. [online] Retrieved from: http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-design-production/evaluating-concrete-defects [Accessed: 13 Apr 2014].

2. Babor B. Plian D. Judele L. (2009) Environmental Impacts of Concrete. [online] Retreived from: http://www.ce.tuiasi.ro/~bipcons/Archive/161.pdf [ Accessed: 20 Apr 2014]

3. Yahoo (2012) How does concrete affect our environment? [online] Retrieved from: https://malaysia.answers.yahoo.com/question/index?qid=20120701010738AA6Fl9t [Accessed: 20 Apr 2014]

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