Introduction Concrete Durability Presented by: Bryan Perrie - PowerPoint PPT Presentation

Introduction Concrete Durability Presented by: Bryan Perrie (presented by Mark Alexander) The Concrete Institute

Introduction “Materials not only affect the destinies of nations but define the periods within which they rise and fall. Materials and the story of human civilisation are intertwined, as the naming of the eras after materials – the Stone age, the Bronze age, the Iron age – remind us”

Introduction Although the principles of “cement” building material fabrication dates back to at least the Roman Empire, it was neglected for centuries I think we are living in the Concrete Age with cement being the most widely consumed material in the world after water and annual concrete consumption of around 31 billion tons.

Introduction Although many ancient structures have lasted for millennia, this was in most cases not the intention. The Roman breakwater > 2000 years Mortar joints intact but stone blocks eroded.

Introduction Why has this changed?

Introduction Why has this changed? • Introduction of reinforcement leading to corrosion. • Development of higher cement strengths, refinement of mix design, increased efficiency using statistics • Strength and workability maintained with lower cement contents • Higher w/c ratios and lower permeabilities

Introduction Why is Durability important? • Very few concrete structures fail structurally, although many deteriorate significantly. • Maintenance of infrastructure way beyond its service life is now common. • End of 20 th C, 250k bridges identified as deficient in US, increasing by 3500 per annum.

Introduction Why is Durability important? • Sustainability is the most important construction issue internationally. • Economic forces make concrete the most suitable material for the majority of the world’s infrastructure

Introduction • Need for sustainable construction products expected to fulfil intended functions, remaining in serviceable condition for long periods with minimal maintenance before being recycled efficiently. • Concrete can be a durable and sustainable material. • Durable concrete need not be maintenance-free concrete

Introduction Questions Can new structures be provided that do not have a negative impact on the balance sheet of our planet’s finite resources? How do we determine an adequate specification without over-specifying (squandering resources) or under-specifying (premature deterioration and third party costs e.g. road user delay)

Introduction Not yet at a stage where specifier and end user engage on key issues including: • design life, • serviceability requirements, • criteria defining serviceability failure, • acceptable level of risk and • required maintenance

Introduction Need to be three developments: • models of deterioration , • tests for properties of concrete and • a probabilistic approach to durability design.

Introduction • Durability issues in SA • The SA Durability Programme • Designing for Durability including mix design and other influences • Practical ways of achieving durability • ‘Case studies’ and open session for Q&A

Introduction Enjoy the seminar