Sustainability In Concrete Structures

Sustainability is important to the well-being of our planet, continued growth of a society, and human development. According to the World Commission of Environment and Development of the United Nations, sustainability means “meeting the needs of the present without compromising the ability of the future generations to meet their needs” (UNFCCC COP9 Rep. 2004).

As a brief on Concrete Structures Sustainability

Concrete Sustainability means:

  • Increasing the mechanical and durability performance of concrete

  • Increasing the possible service life of the concrete structure

  • Reducing environmental impact of concrete

Reducing the environmental impact during concrete production whilst looking at the impact on the performance and durability of the material.

Increasing the sustainability of building structures therefore requires both:

  • Reduction of the environmental impact during erection, maintenance and operation processes as well as

  • Increase of the durability of the structure at maximum technical performance.

This relation can be expressed as:

Sustainability

Environmental Impact of Concrete

Portland cement, the principal hydraulic cement in use today, is not only one of the most energy-intensive materials of construction but also is responsible for a large amount of greenhouse gases. At the current rate of increase of cement production, worldwide cement production is expected to rise from about 2.5 billion ton in 2006 to about 5.0 billion ton by 2020. Producing one ton of Portland cement requires about 4GJ energy and Portland cement clinker manufacture releases approximately 1 ton of carbon dioxide into the atmosphere. Furthermore, mining large quantities of raw materials such as limestone and clay, and fuel such as coal, often results in extensive deforestation and top-soil loss.

Concrete Durability

Durability of concrete has the ability to resist against environmental attacks without its performance falling below a minimum acceptable limit. In an offshore or marine environment, concrete can be subjected to the influences of wetting and drying, freezing and thawing, abrasion by ice and other debris, chemical attack or mineral depletion by water it is in, salt accumulations, and attack by marine organisms.

Three following main factors define the concrete durability:

  • Mix design, quality and relevant quantity of the concrete constituents such as water-to-cement ratio and cement content
  • Construction practice such as mixing, placing, compacting, and curing
  • Environmental exposure conditions

Deterioration of concrete and steel in service result in loss of performance, and it may be the result of a variety of mechanical, physical, chemical or biological processes. The final result of these mechanisms is mainly cracking. Cracking will occur whenever the tensile stress exceeds the tensile strength of the concrete. Corrosion of steel reinforcement is the most serious durability problem of reinforced concrete structures. It impairs not only the appearance of the structure, but also its strength and safety, due to the reduction in the cross sectional area of the reinforcement and to the deterioration of bond with the surrounding concrete.

Role of Technology

Technology plays a very important role in sustainable development because it is one of the most significant ways in which we interact with our environment. We use technologies to extract natural resources, to modify them for human purposes, and to adapt our man-made living space. It is through use of technology that we have seen drastic improvements in the quality of life of many people. Unfortunately, many of these short term improvements in the immediate quality of life have also exacted a great toll on the environment. In order to proceed toward sustainability, we will have to be more deliberate and thoughtful in our employment of technology. We need to develop and use technologies with sustainability in mind. We need “sustainable technologies.”

To avoid confusion and ambiguity it is necessary to establish a working definition of “technology.” Here, the term "technology" is taken to mean "the application of knowledge to the achievement of particular goals or to the solution of particular problems" (Moore 1972, p. 5).

Sustainability In Concrete Structure by Xypex Crystalline Technology

Xypex crystalline products are dry powdered-form compounds composed of Portland cement, silica sand and many active proprietary chemicals.

Xypex's primary and most distinguishing performance feature is its unique ability to generate a non-soluble crystalline formation deep within concrete microstructure.

Xypex products chemically react with moisture and Portland cement hydration products to generate crystalline structure which permanently blocks the interconnected pores and seals cracks with the width of up to 0.4 mm.

The following images show the crystalline growth within the pores and cracks.

Pore Blocking by Xypex Crystalline Formation

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Crack Sealing (a) and Crack Bridging (b) by Xypex Crystalline Formation

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By blocking the pores and sealing the cracks the diffusion rate of the aggressive substances into the concrete is reduced  extraordinarily. This diffusion rate reduction enhances concrete durability. Consequently, the service life of the concrete structures will be extended. Increasing the life time performance of the structure reduces the consumption of raw materials (environmental impact) as well as maintenance and repair costs.

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