Structure, Fractality, Mechanics and Durability of Calcium Silicate Hydrates

Shengwen Tang,Yang Wang,Xiaofei Xu,Hubao A,Zhicheng Geng,Wenzhi Yu,Jingtao Chen

doi:10.3390/fractalfract5020047

Abstract

Cement-based materials are widely utilized in infrastructure. The main product of hydrated products of cement-based materials is calcium silicate hydrate (C-S-H) gels that are considered as the binding phase of cement paste. C-S-H gels in Portland cement paste account for 60–70% of hydrated products by volume, which has profound influence on the mechanical properties and durability of cement-based materials. The preparation method of C-S-H gels has been well documented, but the quality of the prepared C-S-H affects experimental results; therefore, this review studies the preparation method of C-S-H under different conditions and materials. The progress related to C-S-H microstructure is explored from the theoretical and computational point of view. The fractality of C-S-H is discussed. An evaluation of the mechanical properties of C-S-H has also been included in this review. Finally, there is a discussion of the durability of C-S-H, with special reference to the carbonization and chloride/sulfate attacks.

Highlights

The results showed that sucrose changed the reaction mechanism of the calcium silicate hydrate (C-S-H) system as an additive, and the hydrothermal process started from the rapid reaction of sucrose and CaO, and the stable hydrothermal decomposition products formed had a strong inhibitory effect on the formation rate of C-S-H gels
C3 S products are tested, transformation from LD to HD improves the mechanical strength of C-S-H gels
Hu et al studied the interaction between C-S-H and sulfate ions by using nuclear magnetic resonance spectroscopy (NMR) and thermodynamic simulation, and the results showed that the sulfate attack could lead to decalcification and dealumithe defective calcium ions on the surface of C-S-H [209]

Summary

Introduction

The mechanical properties and durability of cement-based materials are of great significance. In terms of mechanical properties, the compressive strength of cement-based materials is quite high. The durability of cement-based materials refers to its ability to resist the effects of environmental media and maintain its good performance and appearance integrity for a long time, thereby maintaining the safe and normal use of materials. The surrounding environment of the concrete structure will have some adverse effects on its durability. Carbon dioxide in the air will reduce the alkalinity of cement-based materials, which will weaken the antirust protection of concrete to steel reinforcement and cause corrosion of steel reinforcement. High durability of cement-based materials will be required in some special environments. In cold areas, cement-based materials will undergo freezing–

Methods

Results

Conclusion