Abstract

The paper deals with the influence of addition of ground granulated blast-furnace slag (GGBS) on the frost resistance of concrete. GGBS is a valuable modifier of concrete, having the latent hydraulic properties and particularly improving the chemical resistance of concrete. However, the performance of concretes with blast-furnace slag under freezing and thawing action is still not explained fully and remains a subject to discussion. The authors have investigated the concretes containing various amounts of GGBS and the portland cement CEM I, with various values of water to binder ratio, with and without the use of air-entraining admixture. The results of research show that the addition of blast-furnace slag causes some worsening of the frost resistance of concrete. The extent of this worsening depends on the water to binder ratio and the aeration of the concrete. However, even under the least favourable conditions, the concretes with GGBS addition have met the requirements of frost resistance after 200 cycles of freezing and thawing, given in the Standard PN-B-06265.

Highlights

  • Ground granulated blast-furnace slag (GGBS) is one of the concrete additions

  • According to PN-EN 206:2016 [1], GGBS is type II addition, together with fly ash and silica fume. It belongs to the group of latent hydraulic materials; PN-EN 206 recommends k value of 0.6 for GGBS used with cements CEM I and CEM II/A

  • An air-entraining agent was used in the constant amount 0.25% of the cement mass. This way the air content in the mixes was obtained as required by PN-EN 206 for the concretes exposed to frost, i.e. 3 4%

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Summary

Introduction

Ground granulated blast-furnace slag (GGBS) is one of the concrete additions. Ground granulated blast-furnace slag is formed by rapid cooling of the liquid slag, which is produced during smelting of the iron ore in the blast furnace. After grinding, it forms fine powder; the grinding process, increasing the specific area of the material, is of favour for its hydraulic activity. The technical properties of cement concretes containing ground granulated blast-furnace slag are not fully recognized yet and their durability under frost action still creates the particular uncertainty. The variable factors were water to binder ratio in the concrete mix and use (or not) of the air-entraining admixtures

Materials used and mix proportions
Methods of testing
Results and discussion
Sum up and conclusions
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