Effect of SCMs on Alkali-Silica Mitigation

ASR

Effect of SCMs on Alkali-Silica-Reaction Mitigation 1- Fly Ash the three characteristics of fly ash that determine its efficiency in preventing ASR are fineness, mineralogy, and chemistry. In general, the finer the fly ash, the more efficient it is in reducing ASR expansion. An ultra fine fly ash, with particle size around 3 μm, can …

Read More

Reasons of Concrete Spalling

Reasons of Concrete Spalling

Concrete Spalling Currently, there are two mechanisms concerning the occurrence of spalling: 1- the pore pressure build up causes spalling in the cement matrix and 2- thermal and mechanical stresses. In 1997, Anderberg gave an account on spalling caused by vapour pressure. The mechanism is believed to be the same for both High Performance Concrete (HPC) …

Read More

Corrosion of Embedded Metals in Concrete

Corrosion of Embedded Metals in Concrete Corrosion of reinforcing steel and other embedded metals is the leading cause of deterioration in concrete. When steel corrodes, the resulting rust occupies a greater volume than the steel. This expansion creates tensile stresses in the concrete, which can eventually cause cracking, delamination, and spalling (Figs. 1 and 2). …

Read More

Carbonation and Corrosion

Carbonation and Corrosion

Carbonation is the term used to describe the effect of carbon dioxide on a material. The phenomenon rarely leads to structural problems but carbonation-induced corrosion can lead to unsightly spalling on structures. The repair costs, for example to multi-storey office development façades, can be considerable. Carbonation of cementitious materials results in a lowering of the …

Read More

Chloride Ingress into Concrete

For concrete structures in chloride-containing environments, the ingress of chlorides can take place in different ways. Through uncracked concrete, the ingress mainly takes place by capillary absorption and diffusion. When a relatively dry concrete is exposed to saltwater, the concrete may suck the saltwater relatively fast, and intermittent wetting and drying may successively accumulate high …

Read More

Alkali–Aggregate Reactions

Alkali–Aggregate Reactions

In this article, the three types of Alkali–Aggregate Reactions are described: (1) alkali–carbonate reaction (ACR), (2) alkali–silicate reaction, and (3) alkali–silica reaction (ASR). Alkali–Aggregate Reactions Water in the pores of hardened concrete contains quantities of dissolved ions largely deriving from the cement matrix. In mature concrete, the vast majority of dissolved cations are those of the alkali …

Read More

Concrete Distress Identification

Concrete Distress Identification

Distress Identification Before attempting any repair procedure it is necessary to have a planned approach to investigate the condition of concrete and reinforcement. While the diagnosis of damage or deterioration in some cases is reasonably straightforward, it may not be so in many cases. Particularly difficult are cases in which the cause and effect phenomenon …

Read More

Visual Defects of Concrete

concrete deterioration

Visual Defects of Concrete: one of the simplest ways to understand what exactly causes concrete to fail would be performing a Visual Survey of the deteriorated concrete structure. When a client hires an Engineer to inspect a concrete structure, it is most likely because the owner visually noted some form of deterioration. This, technically, may be considered a …

Read More