Conducting pull out test in concrete

Bond between concrete and steel is an important parameter. As concrete grows old, the bonding generally deteriorates. In this article, the method to conduct pull out test to estimate the bond strength is discussed. In the case of plain rebars, the maximum load almost same as the instant for first slip, while in the case …

Interfacial Transition Zone

The bonding property of cement with aggregate is achieved via Interfacial Transition Zone (ITZ). In this article, the reason for formation of ITZ and its impact in the overall life of concrete will be discussed.

Bonding behaviour in ASR affected concrete

Alkali Silica Reaction (ASR) has been found to deteriorate the bond between steel and concrete. This article will discuss if this is true. The early study regarding effect of ASR on the bond strength was done by Chana (1989) in Britain from Transport and Road Research Laboratory. The experiment was extensive. The Na2eq was taken …

Concrete with microbial

Conventionally, organic matters in concrete was considered to be undesirable. But recent study with selected microbes has shed new light on its usefulness. Both useful and deteriorating microbes has been identified. Metabolic activity of microbes produces acid which degrade concrete. These kind of deterioration is pronounced in location having high microbial activities such as near …

Abrasion of concrete

Abrasion of concrete is progressive loss of concrete mass due to mechanical degradation such as friction, grinding action, impact, overloading and local crushing. Vehicular movement and pedestrian traffic causes abrasion.  The worst effect of abrasion is caused by vehicle with studded/chain tyres. Similarly, in industrial buildings, the concrete floors are subjected to impact load and …

Cavitation of concrete

Cavitation is a physical process that causes pitting of surface due to rise in local pressure by collapse of vapour bubbles. Cavitation can damage the concrete in following ways: (i) due to shock waves generated by bubble implosion;(ii) by the micro-jets due to bubble implosion;(iii) collapse of bubble clusters Cavitation generally occurs in hydraulic channel …

Impact of bad formwork in service life

Formwork are a crucial part of reinforced concrete (RC) design. It supports the concrete until concrete gains sufficient strength. Depending upon the shape, formwork can be as simple as a cubic box to as complected as spline surface. While design of formwork is itself a major field of concrete engineering, here in this article, the …

Leaching in water retaining structures

Without water cement cannot get hydrated. However, after the hydration process has been completed, the presence of water can dissolve the hydration product and degrade the structure. This is more true for water retaining concrete structures. For example, in the case of dam, the hydrostatic pressure coupled with water permeability can leach out the hydration …

Leaching

Structures such as dam where the flow of water via pores of concrete is high, there could be significant loss of mono-sulfate and ettringite and decalcification of calcium silicate hydrate due to leaching out of these salts to the surface and subsequently washing away. This will lead to reduction in strength of concrete and increases …

Durability of concrete in terms of water permeability

Permeability is one of the main indicator defining the durability of the concrete.  In one hand, the permeability of the concrete can be high from the beginning of concrete life, in which case, the deterioration takes place rapidly during the service life. While in the  other hand, the permeability of the concrete may gradually increases …