Effect of Rheology of Fresh Paste on the Pore Structure and Properties of Pervious Concrete Based on the High Fluidity Alkali-Activated Slag

Haining Geng,Saiful B Duraman,Qiu Li,Qing Xu

doi:10.3390/cryst11060593

Abstract

Pervious concrete is made of cementitious materials, coarse aggregate, water and additives, with characteristic macro- and meso-connected pore structure, which enables the acceptable mechanical properties and high water permeability for pavement and road applications. In this study, the effect of rheology of fresh alkali-activated slag paste on the sedimentation of paste on the bottom of pervious concrete, meso-structure, connected porosity, mechanical properties and water permeability was investigated by a range of analytical techniques through varying the equivalent alkali content to control the rheology of fresh paste in the pervious concrete. The compressive strength of pervious concrete was related to the percentage area of paste and the average thickness of paste on the surface of coarse aggregate. The tensile strength and water permeability were correlated to the connected porosity of pervious concrete and the rheology of fresh paste. A relative lower fluidity, higher viscosity and shear stress of fresh alkali-activated slag paste favoured lower sedimentation of paste on the bottom of pervious concrete, higher connected porosity, tensile strength and water permeability. There was no correlation between compressive strength and tensile strength of pervious concrete.

Highlights

IntroductionPublisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations
The differences of rheology between various cementitious materials were investigated and the results indicated that the shear stress of water glass-activated slag was higher than that of Portland cement and sodium hydroxide-activated slag, which could be related to the formation of C–S–H in the former [30]
The effect of alkali equivalent on the fluidity and sedimentation of paste, pore structure, mechanical properties and water permeability of pervious concrete was characterized by a range of analytical techniques

Summary

Introduction

Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Pervious concrete is an eco-friendly construction material that consists of cementitious materials, coarse aggregate, water and additives [1]. The characteristic connected macropore structure of pervious concrete enables the high water permeability and acceptable mechanical properties as pavement materials, which are widely used in car parks, gardens and sometimes roads [2,3]. The porosity of pervious concrete is usually between 15% and

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