Environmental Friendly Concrete

INTRODUCTION

The future of all construction materials lies in the conservation of the earth’s depleting resources. Sustainability and recycling of concrete waste are key to this construction ethos. 

Concrete is more of an environmentally friendly material than many perceive it to be. Its production involves relatively little energy. In buildings and structures, it generates no emissions, needs no toxic preservatives and is inherently resistant to fire. Concrete can also be recycled. Waste from both from demolition and the ready mixed plant can be used as an aggregate or even a sub-base for roads.

Self-compacting concrete, as mentioned above, eliminates the need for energy intensive compaction on site.

A new development in office buildings is the use of concrete’s thermal capacity – its ability to absorb, store and radiate heat. This helps to save energy by regulating air temperature and thus reducing or eliminating the need for air-conditioning.

After water, concrete is the most used material on earth. it’s no wonder, because it’s the most versatile building material in the world. It is used to construct the infrastructure, roads, bridges etc. on which Ireland’s economic success depends. We build towns and cities in concrete in the expectation that they will last for generations. It is used extensively on our farms where huge concrete tanks are built to retain millions of gallons of toxic animal slurry. ​

Concrete has amazing physical properties and can even survive extreme, hostile climatic conditions such as in the North Sea where it is used to construct oilrigs.

 Concrete home building materials, including concrete blocks have excellent environmental credentials. Firstly, they are among the most durable of building materials. Concrete blocks will not warp, rust or rot and require little or no maintenance. Steel and timber on the other hand, consume considerably more energy in their maintenance and often require the use of toxic paints and preservatives to extend their service life. Whereas, many materials which are perceived as environmentally friendly lose their structural strength after a short number of years, the concrete block used in the construction of your home is likely to get structurally stronger with age. Concrete’s extremely long service life means not having to return to the environment for more materials and energy to repeat the task.

 In many countries concrete is a locally produced material, concrete has another advantage over other building materials. On average concrete is manufactured within a 30 mile radius of the building site. 

 This means substantial energy savings compared to materials such as timber, which are often transported,from Brazil, Canada and Scandinavia where the removal of trees often has a negative environmental impact.​ 

CEMENT/ CONCRETE AND ENVIROMENT

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 Like glass and paper, for which recycling structures have been put in place, concrete is an ideal material for recycling. In Canada for example, concrete demolition waste is currently mined from existing waste dumps and re-used as a base for roads. The Forum for the Irish Construction Industry recently published an investigation on the potential to recycle construction and demolition waste. The report has set the agenda for the development and implementation of a voluntary construction industry program to meet the government’s objectives for the recovery of construction and demolition waste and its re-use in new projects. When implemented, this will mean that the cement and aggregates used in today’s home construction programs will be collected and reused to build the roads and infrastructure required by future generations.​​

Sustainable development involves meeting present needs without compromising the ability of future generations to meet their needs .Any cement & concrete industries will be expected by its stakeholders to develop progressive policies on environmental performance improves in unison with social & economic performance. The industries are strategically important for the bulk of construction i.e. housing, schools, hospitals ,commercial buildings ,industrial building ,water supplies ,railways ,roads & bridges .The commercial activity & employment associated with construction & the use of concrete have significant social & economic benefits , concrete sector sales in $billions & direct employment figure in thousands .

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The difference is ICF (insulating concrete forms), a building process well established in North America. Approximately 40,000 ICF homes have been built since the early 90’s. Currently about 100 distributors and manufacturers of ICF systems serve the Canadian market. For the custom homebuilder, ICF represents a real advantage. It’s fast to build, easy to manipulate, and requires a small number of skilled laborers – a real advantage in today’s market with the shortage of skilled framers.

Concrete and other cement-based products have formed the basis of Canada’s physical infrastructure and now touch virtually every aspect of daily life.

Since 1889, when Portland cement was first introduced in Canada, the industry has developed increasingly progressive materials, designs and construction methods.

But for all its sophistication, modern concrete retains the stone-like properties that have made it the foundation of all we build – durable, fire resistant and immune to rot and rust.

The Canadian cement and concrete industries employ some 22,000 people and generate annual sales of over $4 billion.

Cement is produced at 16 locations across Canada, cement-based products at more than 1,100 locations.

The Canadian cement industry has earned an excellent reputation for innovation, product quality, environmental performance and research.

Economics dictate that cement and concrete facilities be located near raw materials and markets.

As a consequence, the investment and jobs associated with facilities are intimately connected to the growth and stability of communities in which they operate.

As active members of the community, the cement industry takes pride in its commitment to responsible corporate citizenship on all operational matters, including safety and environmental performance.

Concrete is the most widely used constructional material in world .In Canada it is used about 10 Kg. per person per day .

Stone –like material is produced from some of the world‘s most abundant resources as its key ingredient, cement. Concrete‘s appeal also lies in its physical properties durability. Visual appeal & design flexibility. It is practically inert, contains no toxic components & gives off no emissions. Concrete would not burn & offers acoustic resistance .It can take on virtually any color, texture or shape imaginable.

The production of cement is energy intensive ,its end product is concrete ,usually contains only 9-13% cement . In fact concrete ‘s other major components aggregates & water make its production energy efficient because they are naturally occurring ,low energy materials .

Figure 1 ,shows the energy intensity required to produce some constructional materials in Canada (1975-1983).It was derived from Environmental Auditing  for Building Construction(4) by R.J. Cole & Rousseau, UBC, school of Architecture , the energy intensity is defined as the energy used to produce a unit quantity of material & the embodied energy of a component, assembly or structure as the amount of energy to produce & install the constituent materials & components of building. The energy intensity of concrete   is among the lowest of commonly used building materials, also concrete displays an enviably low life cycle cost due to its long life, low maintenance requirements & low embodied energy.

Due to many research, reports & studies on the effect of the concrete on environments, many parameters have been improved which makes concrete more friendly to the environments as shown in Table (1).

Table (1) Parameters per kilo-ton of concrete :( Dr. Les Parrott, 2002 derives it from a report on the progress of the UK Cement & Concrete industry towards Sustainability) (7)

The above table shows that there was a reduction of fossil energy in 2001 & a decrease in electrical energy consumption and the lower thirteen rows of above table show key indicators of the environmental impact of concrete .There has been an average improvement ,over this basket of indicators ,of 17% from 1994 to2001 ;the main improvement has been in emissions to air .Using the same set of indicators 40% and 8% of the environmental effects of concrete in 2001 were attributable to Portland cement & reinforcing steel manufacture, respectively.

CONCRETE IN LIFE

Concrete was chosen by the City of Coquitlam as a pavement that would hold up against the heavy weight vehicle usage of Pine tree Way, And due to increasing of  Traffic volumes have been increasing steadily over the past several years and are now in the range where twinning is an appropriate measure for increasing highway service levels. It is recognized that the twinning of this section of highway 101 will improve its safety performance and help the Nova Scotia Government in its goal to make its roads safer. Concrete shows   many social, economic, environmental, & technical advantages in buildings,agriculture, housing & transportation applications.

The Canadian cement and concrete industries employ some 22,000 (1) people and  in Uk employ some 27000(6) people i.e. around 5% to7% of  the country  workforce , and consequently generated annual sales of many billions, that improve the social life of many families in the society .

In the past twenty years , energy consumption per ton of product has been reduced nearly 25% for environmental & economic reasons ,the industry continues to seek improvements by replacing outdate equipment with new more efficient technology-current research suggests that the introduction of low cost catalysts could reduce fuel requirements & increase production by as much as twenty percent, although Figure (1) above shows that  in concrete production the energy intensity per unit weight is the minimum among many constructional materials.

Computers have helped cement manufacturers to improve the consistency & quality of cement; they also enable ready- mix plants to batch concrete mixes more accurately so that a ton of concrete can go farther today than it did in the past.

Although concrete is considered a friend to the environment & safe materials ( Refer to the MSDS, material safety data sheet attached at the end of this assay), they industry has explored several ways to reduce , reuse & recycle ,which they call it the three “R”s application;

Reduce;

The partial replacement of Portland cement in concrete by fly ash or slag ,by products of coal firedelectrical generating  plants & the steel industry respectively , is now an accepted practice .Work on these supplementary cementing materials .and the design of appropriate mixes has produced good results .Waste derived fuels such as spent solvents ,used oils tires & other high energy content industrial, commercial & biomass wastes can replace a significant portion of the local coal or natural gas used as cement kiln fuel .Currently one half of Canadian cement manufacturers are burning wastes as supplemental  fuel.

Reuse;

Many concrete products can be reused .concrete pavers, lifted for underground repairs ,are regularly put back where  they were .Pre cast wall panels can be reused when buildings are expanded  .Concrete side walk slabs are reused  to build “dry stone” retaining walls & often concrete pieces from demolished structures are reused to protect shore-lines.

Recycle;

Concrete can be recycled as granular fill, as base course for pavement or as aggregate for new concrete .Control of particle size in crushing & removal of contaminants from other demolition materials  is required. At present this is easiest in road construction ,where the new concrete can include up to 100% recycled course  aggregate & recycled fines can  replace10-15% virgin sand. At its 20.acre Lakeshore Village project in Etobicoke ,the Daniels Group demolished an old multi-storey tire plant& crushed 100,000m3 of concrete for use as pipe bedding & backfill on site.

CONCLUDING POINTS ON CONCRETE/ENVIRONMENT/SUSTAINABILITY

REFERENCES