Durability and chemical resistance of nanoparticles fly ash and silica fume belite cement pastes against sulfate and chloride aggressive media- Part II

Darweesh H.H.M

doi:10.54392/nnxt2141

Abstract

The durability (chemical resistence) of the Portland cement (OPC), belite cement (BC) and the optimum belite cement (B4), which their physical and chemo/mechanical properties were perviously investigated in Part I, against 4 % MgSO4 and 4% MgCl2 solutions up to 12 months in terms of compressive strength, total sulfate and total chloride was evaluated and studied. Results showed that the optimum belite cement (B4) containing 15 % High pulverized fly ash (HPFA) and 5 % Silica fume (SF) could be resisted up to 6 months, while that of BC could be withstood only up to 5 months, and the OPC could not resist more than three months of immersion in 4% MgSO4 solution. The compressive strength values exhibited by the samples immesed in sulfate solution at 3, 5 and 6 months of immersion were 83.81, 76.38 and 91.13 MPa, respectively. The same trend was displayed when the same samples were exposed to 4% MgCl2 solution. The compressive strength values exhibited by the same samples exposed to chloride solution at 3, 5 and 6 months of immersion were 84.49, 82.23 and 93.32 MPa, respectively. The total sulfate and chloride contents were enhanced with immesion time up to 12 months, but their values were the minimum with B4 and the maximum with OPC, while with BC were the medium. The optimum cement batch (B4) achieved the highest resistance where it recorded the lowest values for sulfate and chloride ions, but the OPC exhibited the lowest resistance where it recorded the highest values of sulfate and chloride contents at all immersion ages till 12 months.

Highlights

1.1 Scope of the problemThe gradual and continual dominance of cementitious building materials for various constructions is a response due to its increased strength, resistance and versatility when compared with other building materials, e.g. steel, glass, wood and so on
The durability of the Portland cement (OPC), belite cement (BC) and the optimum belite cement (B4), which their physical and chemo/mechanical properties were perviously investigated in Part I, against 4 % MgSO4 and 4% MgCl2 solutions up to 12 months in terms of compressive strength, total sulfate and total chloride was evaluated and studied
Results showed that the optimum belite cement (B4) containing 15 % High pulverized fly ash (HPFA) and 5 % Silica fume (SF) could be resisted up to 6 months, while that of BC could be withstood only up to 5 months, and the OPC could not resist more than three months of immersion in 4% MgSO4 solution

Summary

Introduction

1.1 Scope of the problemThe gradual and continual dominance of cementitious building materials for various constructions is a response due to its increased strength, resistance and versatility when compared with other building materials, e.g. steel, glass, wood and so on. Chemical reactions of the nanopozzolanic materials with the evolved calcium hydroxide, or free lime Ca (OH) due to hydration in the pore solution of cementing composites often form more calcium silicate hydrate which soon precipitated in the pore structure of the hardened cement pastes. This in turn decreases the total porosity and increases the bulk density. The hydration reactions of Portland cement with water have been found to be expedited in the presence of nanomaterials This resulted in the formation of more calcium hydroxide [4,5,6,7,8,9]. This can be contributed to the nanomaterials that are serving as nucleation site areas for the formation of hydration products due to its NanoNEXT 2(4) (2021) 1-13

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