A Comparative Study of Void Distribution Pattern on the Strength Development between OPC-Based and Geopolymer Concrete

Ali Nazari,Ali Bagheri,Hasnat Tariq,Parth N J A Yadav,Jay Sanjayan

doi:10.1155/2019/1412757

Ali Nazari, Ali Bagheri + Show 3 more

Open Access

https://doi.org/10.1155/2019/1412757

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Abstract

The correlation between the void structure, as a representative of bleeding behaviour, and the strength of concrete is investigated in the current article. Early age cracking, due to dry shrinkage, can negatively influence the durability of pavement structures. Also, dry shrinkage of concrete is directly proportional to the bleeding rate. Thus, modifying the bleeding rate reduces the early cracking that happens in hardened concrete. Geopolymer concrete is presented as a suitable material for the replacement of Ordinary Portland Cement (OPC). Geopolymers have shown superior bleeding behaviour to that of OPC concrete and can be substituted for paving by means of increasing the durability. This research has used section image analysis and rebound hammer techniques to create a relationship between the void structure and the strength of concrete. Mixtures are prepared by 10% substitution of the iron-making slag to study the effects of slag on the bleeding rate. Also, the influence of water-to-binder ratio on the void structure and strength development is studied. The results indicate that the void volume has an indirect correlation to the strength development of normal concrete, while the addition of slag makes it reverse. Geopolymer concrete shows less bleeding than OPC concrete, making it a suitable alternative for pavement. It is also concluded that the replacement of slag in concrete enhances the bleeding rate and durability.

Highlights

Bleeding in concrete is a phenomenon that describes water movement to the surface in a plastic state concrete [1,2,3]
James Aldred noticed that geopolymer concrete showed no sign of bleed water on the surface compared with Ordinary Portland Cement (OPC) concrete [23]
Fineness and quantity play significant roles in the characteristics of the final product. e particle size distribution (PSD) of the utilised fly ash is as that of reported in Figure 1(a). e OPC used in this study for making traditional concrete specimen is general purpose cement type GP

Summary

Introduction

Bleeding in concrete is a phenomenon that describes water movement to the surface in a plastic state concrete [1,2,3]. E result showed that an increase in the cement content from 250 to 350 kg/m3 causes a reduction in bleeding by 50% and 60%. James Aldred noticed that geopolymer concrete showed no sign of bleed water on the surface compared with OPC concrete [23]. The loss of water from the surface during the drying process leads to a reduction in volume. E higher water-to-cement ratio affects because a higher volume of water in concrete causes bleeding on the surface. It results in an increase in shrinkage. It is suggested to measure the void profile of the concrete section and make a correlation between the changes in the void variation and the strength development

Materials and Methods

Test sieve size

Concrete specimen