Predicting Durability and building life expectancy

Concrete is one of the most used engineering materials on tonnage basis. Life cycle Cost of projects depends on durability of building materials and components hence durable concrete is very very important with regards to structure’s life span. Durability can be defined as material’s ability to resist environmental (internal & external) conditions while maintaining desired engineering properties.

Factors affecting durability of concrete structure are divided into two parts:

  1. Concrete degradation
  2. Rebar corrosion

Concrete durability depends on :

factors affecting durability of concrete

Contrary to common belief, concrete is a complex composite material, whose structure and properties can change over time.

It is generally recognized that the environmental degradation of the concrete infrastructure is a serious, large scale and costly problem in many parts of the world

Transport mechanism of environmental degradents in concrete

Some weaknesses or new factors of degradation added to this because of operational practices eg.

  1. Concrete mix esp at site
  2. w/c ratio and its distribution
  3. vibration & mixing uniformity
  4. curing conditions
  5. nature of bond between cement and aggregate etc

Concrete vulnerability variable-some well-known factors are listed in above two figures- are huge in numbers so  quantitative estimation and control of durability and retaining engineering properties at a desired level becomes very complex task, a model and a software to carry out accurate calculations was much needed  to simplify this.

Designing reinforced concrete structure wrt various concrete mix, exposure condition, ingredient & life cycle cost and expected service life is very complex due to huge numbers of variables. To tackle this Life-365 consortium was formed in USA by various concrete related organizations so that collective knowledge & expertise can be combined to develop life-365 service life prediction model which allows users to input local concrete-chloride profile to customize the model to their worldwide location and environments.

You can download Life-365 service life prediction here : Life-365

Life-365 is software designed to estimate the service life and life-cycle costs of alternative concrete mixture designs proportions and life-cycle costs of alternative concrete mixture designs proportions and corrosion protection systems.  It follows research-based methodology developed by the Life-365  Consortium I and II groups of companies, that gives estimates on the effects of design, chloride exposure, environmental temperature, high-performance concrete mixture proportions, surface barriers, and steel types on the service life and life-cycle cost of steel-reinforced concrete structures.

This simple and transparent model provides a fundamental tool for design consultants to use for estimating the service life and life cycle costs of alternate protection systems in their design of steel-reinforced concrete structures that will be exposed to chlorides.