Effect of micro silica and slag on the durability properties of mortars against accelerated carbonation and chloride ions attack

Document Type : Research Article


1 civil and environment engineering, amir kabir university of technology , tehran , iran

2 Faculty of Civil Engineering, Amirkabir University of Technology, Tehran, Iran

3 School of Civil Engineering, University College of Engineering, University of Tehran, Tehran, Iran


Nowadays, as the cities grow, more carbon dioxide is emitted to the atmosphere moreover, chloride ions dissolved in water would reach the concrete whenever it rains consequently, they can help increase the corrosion of bars implemented inside concretes, therefore investigation of the effect of carbonation and chloride ingress is of paramount importance.
Mortars were made with three water to cement ratios of 0.485, 0.44, and 0.4 also the flow of the mortars were kept in the range of 18 to 20 centimeters. The mixtures were prepared with ordinary Portland cement and artificial pozzolans (Ground Granular Blast Furnace Slag and Micro-Silica) as supplementary cementitious materials. The cement replacement percentage was 20% intended for slag containing samples and 7.5% used for micro-silica containing samples.
The durability properties of mortars were investigated through capillary water absorption test, electrical resistivity, carbonation depth, and chloride ions penetration according to NT Built 443. Also, the mechanical characteristics of mortars were measured by the compressive strength test.
The results revealed that Micro-silica enhanced the mechanical and durability properties of the specimens except for their resistance against carbonation, in both environments while, the addition of slag had some drawbacks in compressive strength and carbonation resistance. However, the addition of Slag helped specimens augment other durability properties.
It can be concluded that using Micro-Silica is a magnificent option to enhance the mechanical and durability properties of mortars. The contribution of Slag has also shown to be helpful in enhancing durability properties of mortars but not as much as Micro-Silica.


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