Sustainable Concrete Construction in the 21 st Century: Challenges & Opportunities

1. Sustainable Concrete Construction in the 21st Century: Challenges & Opportunities Dr. Mohamed Lachemi, P.Eng. Department of Civil Engineering Ryerson University

2. Outline • Introduction • Current Situation • Challenges • Opportunities • Research Activities Canada Research Chair in Sustainable Construction

3. Construction Industry Today In Canada, the construction industry generates annually $110 billions and creates almost 1 million jobs. Worldwide, this sector generates around US$3.5 trillion.

4. Construction Industry Today Issues facing the industry: • Little emphasis on R&D; • Poor image; • Mobile workforce; • Poor productivity.

5. What is Sustainable Development? "Sustainable development meets the needs of the present without compromising the ability of future generations to meet their own needs." United Nations World Commission on Environment and Development

6. Sustainability & Construction Sustainable development in construction should translate into: • Improved quality of life; • Protection of the environment; • Energy conservation; • Waste reduction & recycling; • Efficient use of natural resources; • Better operational performance.

7. Concrete in our lives Concrete is the most widely used construction material in the world. Worldwide, the yearly production of concrete is of the order of 13 billion tonnes. Humankind consumes only water in larger quantities.

8. Concrete in our lives Concrete (concretus) is the key material for Mankind to create the built environment

9. Concrete in our lives What would modern civilization be without concrete?

10. Cement Water (Additives) Aggregate Concrete What is Concrete?

11. Properties of Concrete Concrete is relatively inexpensive, strong, versatile, and resistant to fire, impact, water, and weather. It has also a longer service life than most construction products and requires little maintenance.

12. How Good is Good Enough? Concrete can be made to last as long as we want it to.

13. How Good is Good Enough? Concrete can be made to last as long as we want it to.

14. How Good is Good Enough? Concrete can be made to last as long as we want it to.

15. How Good is Good Enough? Why do Modern reinforced concrete structures begin to deteriorate in 20 years or less?

16. The Problem Because we use so much concrete, and because concrete has competing materials for many applications, the tendency is to provide the concrete at the lowest possible cost.

17. The Current Situation In the US, it will cost US$2 to US$3 trillion over the next 20 years to repair all the concrete structures which are now deteriorating from corrosion and are poorly made and maintained. National Research Council Report, 1990.

18. The Current Situation In Canada, it is estimated that the cost of repair all concrete structures is in the range of $75 billion.

19. New Perspectives High-performance and durability should be given high priority in the selection of materials and construction practices.

20. High Performance & Durability The Confederation Bridge Expected life cycle : 100 years The ice shields are exposed to salt water, freezing and thawing and ice abrasion.

23. PEI Girder Eiffel Tower 7800 t 7200 t

24. Is the Confederation Bridge Safe?

25. Another Challenge We need to learn how to better realize the potential of concrete as construction material by producing it with the use of less energy and smaller emissions of greenhouse gases.

26. CO2 Gases & Energy Consumption The production of one ton of cement releases about one ton of CO2 into the atmosphere. This contributes to what is now commonly called global warming.

27. Cement Production

28. Life Cycle Analysis Emissions & Energy Natural Resources SCM & Additives Water and Aggregates Cement Production Resource extraction Life Cycle Recycling Lime Pit Use of waste materials Re-use Classifying Demolition Landfill Design Adapted from Lambros & Androus

29. Opportunities The construction industry is by far the most promising sink for recycling industrial, mining, and household wastes because of the large volume of materials used and its tolerance for variability in their properties.

30. Vision This Canada Research Chair in Sustainable Construction is driven by a vision that large volumes of waste products can be transformed into useful construction materials, providing economic gains, health benefits, and environmental relief.

31. Waste & By-product Materials • Slag; • Fly ash; • Silica fume; • Cement kiln dust; • Industrial sludges; • Limestone screening & quarry dust; • Incinerator ash.

32. Fly Ash in the Construction Industry

33. Fly Ash in the construction Industry

34. Coal-Ash Production & Utilization

35. New Generation of Products • High performance concrete (HPC); • Self consolidating concrete (SCC); • Reactive powder concrete (RPC); • Flowable fill; • Structural fill; • Roller compacted concrete (RCC).

36. Our Focus Self Compacting/Consolidating Concrete (SCC) is among the new materials that can be used for some of our pressing needs for high performance and more durable materials, and innovative construction methods in the 21st century.

37. New Generation of Concrete The problem of the durability of concrete structures due, among other things, to a significant reduction in the number of skilled workers in Japan's construction industry has led to the development of SCC in the beginning of 1990s.

38. What is SCC? SCC must: • Have a fluidity that allows self-consolidation without vibration, • Remain homogeneous during and after the placing process, and • Flow easily through reinforcement.

39. How to Achieve Self-Consolidation? • Limiting the coarse aggregate content; • Increasing the paste content; • Using a superplasticizer and lowering the water-to-powder ratio (W/P). Okamura and Ouchi, RILEM Symposium on SCC, Stockholm 1999

40. Benefits of SCC • Substantial reduction in construction time and labour cost; • Substantial reduction in the exposure to compaction and vibration noise; • Proper filling of restricted access areas and heavily reinforced members; • Facilitating constructibility with superior surface quality and finishing.

41. Benefits of SCC (Our Approach) • Optimization of cement use; • Safe disposal of waste products; • Increased life-span of structures; • Reduction in Greenhouse Gas Emissions.

42. Use of SCC SCC has already been used in several countries. In Japan, major construction projects included the use of SCC in the late ’90s. Today, in Japan, efforts are being made to free SCC of the “special concrete” label and integrate it into day-to-day concrete industry production.

43. Use of SCC in Japan The Akashi-Kaikyo Bridge: the world’s longest suspension bridge

44. Use of SCC in Japan The use of SCC shortened the anchorage construction period by 20%, from 2.5 to 2 years.

45. Use of SCC in Japan Osaka Gas Terminal: the World’s Largest PC LNG Storage Tanks

46. Use of SCC in Japan • In addition to enlarging the capacity of the new tanks, the use of SCC technology resulted in: • A decrease in the number of concrete workers from 150 to 50; and • A decrease of construction time from 22 to 18 months. Osaka Gas Terminal

47. Use of SCC in Japan Osaka Gas has conducted a number of studies over the years that eventually led to the development of a safe and reliable world-record capacity 180,000-m3 PC LNG storage tank. In addition to the advantage of the scale brought about by increasing the tank capacity, construction costs were significantly reduced by more than 10% by aggressively introducing various new technologies that reduced construction cost and period. In terms of the land use, the 180,000-m3 PC LNG storage tank can be installed in the same space used for a 75,000-m3 double-walled metal tank, which is an improvement in land use efficiency of 2.5 times. Osaka Gas Co. Website

48. Our Research Activities Novel concrete mix design Material characterization Environmental & other benefits Sensors & NDE (actual structures) Structural performance models Structural evaluation Smart monitoring & testing Lab studies Long-term behaviour & durability models Durability evaluation Field studies

49. Will SCC Become the Standard for Designing Concrete Structures? “One cannot design and work with a material which one does not know and understand thoroughly. Therefore, design quality starts with education.” Prof. Jorg Schlaich

50. Our Mission Our mission is to educate the future leaders of the profession and to provide skills and foundations for life-long learning and growth.