Effect of Low‐Dosage Linear Silane on the Micro‐ and Nanostructure and Mechanical Properties of Calcium Silicate Hydrate

In previous studies, silanes have often been used as admixtures in cement. The main hydration product of cement is calcium silicate hydrate (C–S–H), and the essence of silane's application is the modification of C–S–H. However, when used as admixtures, the dosage of silanes is generally in the percentage range. This paper selects three common silanes and comprehensively assesses the effects of silanes at low dosages in the per mille range on the microstructure and mechanical properties of C–S–H, providing theoretical guidance for possible practical applications. In this study, the use of a small amount of linear silane as a modifier promoted the formation of layered stacking structures in calcium silicate hydrate. In this study, three linear silanes were used to modify C–S–H, namely (3‐Aminopropyl)triethoxysilane(APTES), 3‐(Trimethoxysilyl) propyltrimethoxysilane(γ‐MPS), and 3‐Mercaptopropyltriethoxysilane (MPTS). FTIR results show that the three linear silanes promoted Si─O bond formation. NMR analysis indicates they increased the average chain length and polymerization degree of C–S–H. TG shows a slight decrease in thermal stability for all modified samples. BET results reveal increased cumulative porosity across all samples. SEM and AFM images show that APTES promotes a distinct layered structure, while γ‐MPS and MPTS cause minimal changes. Mechanical testing shows the Young's modulus of APTES‐modified C–S–H increased by ∼65%, whereas γ‐MPS and MPTS reduced elastic modulus. These differences are due to how each silane affects particle arrangement and microstructure, with APTES favoring ordered layering.