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Durability of concrete structures is primarily dependent on the environmental influences, i.e. the penetration of aggressive substances in the structural element from the environment. Penetrability is an important durability indicator of concrete and by specifying different classes of penetrability of concrete it should be possible to design a structure with the required resistance to environmental loads. This chapter covers descriptions of the available and commonly applied in situ and laboratory, non-invasive and semi-invasive test methods for evaluating concrete penetrability properties.

This chapter presents an overview on several performance-based approaches for concrete durability specification and conformity assessment of the as-built structure.

Durability of concrete is in part determined by its resistance to the penetration of deleterious substances entering as a liquid or gas that is considered to be a function of its permeation capacity. Permeation capacity is controlled by the connectivity of pores that exist in the cementitious matrix and paste-aggregate boundaries. The presence of chemical admixtures in a mixture can greatly reduce the permeation capacity of hardened concrete by several orders of magnitude. Permeability-reducing admixtures are effective in blocking capillary pores by making them hydrophobic as well as depositing pore-blocking products into the pores. This paper presents an experimental study into the effectiveness of using permeabilityreducing admixtures including hydrophobic pore blockers and crystalline self-sealers. Concretes with increasing w/c ratios of 0.4, 0.5 and 0.6 have been investigated. The effect of admixtures on water penetration has been assessed through monitoring the changes in mass transport mechanisms. In addition to the available standard test methods, the coefficient of permeability of water has been directly determined using a specially developed test method described in this paper. Results indicate that permeability-reducing admixtures can reduce the water penetration of concrete significantly if used correctly and if the design intent is defined.

Durability of concrete is in part determined by its resistance to the penetration of deleterious substances entering as a liquid or gas that is considered to be a function of its permeation capacity. Permeation capacity is controlled by the connectivity of pores that exist in the cementitious matrix and paste-aggregate boundaries. The presence of chemical admixtures in a mixture can greatly reduce the permeation capacity of hardened concrete by several orders of magnitude. Permeability-reducing admixtures are effective in blocking capillary pores by making them hydrophobic as well as depositing pore-blocking products into the pores. This paper presents an experimental study into the effectiveness of using permeabilityreducing admixtures including hydrophobic pore blockers and crystalline self-sealers. Concretes with increasing w/c ratios of 0.4, 0.5 and 0.6 have been investigated. The effect of admixtures on water penetration has been assessed through monitoring the changes in mass transport mechanisms. In addition to the available standard test methods, the coefficient of permeability of water has been directly determined using a specially developed test method described in this paper. Results indicate that permeability-reducing admixtures can reduce the water penetration of concrete significantly if used correctly and if the design intent is defined.

QC 20120130. Chapter 4-7

Chapter 4. QC 20120130

QC 20120123. Extended version on conference CD, pp 10

The comparative test that deals with the NDT assessment of the actual cover depth to reinforcement in new structures, using commercially available covermeters was discussed. The capability of different covermeters to assess the cover to reinforcement was checked by using them in different environmental conditions. The comparative test proved that all instruments are capable to measure with 100% success the depth of the concrete cover within an accuracy of ±10%. The assessment of the cover depth was not significantly affected by the temperature and moisture conditions.