A multi-method approach was used for the investigation and comparison of alkali-activated slag binders (AAS), pure slag and ordinary Portland cement (OPC). X-ray fluorescence, X-ray powder diffraction, granulometry, calorimetry, thermo-gravimetric analysis and environmental scanning electron microscope investigations of the microstructure with energy dispersive X-ray analyses were used to characterise the cements and their hydrate phases. In addition, the chemical composition of the pore solution, including the different sulphur-containing ions, was analysed. The precipitation mechanisms during binder hydration in the AAS and OPC systems exhibit significant differences: in AAS the formation of the ‘outer product’ C-S-H is much faster than in OPC. The high Si concentrations in the pore solution during the early hydration of AAS are related to the fast dissolution of Na-metasilicate. The fast reaction of Na is an important factor for the voluminous precipitation of C-S-H within the interstitial space already during the first 24 h. In addition to the Na-metasilicate component, the high fineness of the slag represents a further important factor for the fast hydration of AAS. The small slag particles (&lt; 2 μm) are completely dissolved or hydrated within the first 24 h, whereas hydration of the larger particles is much slower. The fast formation of a gel-like matrix in AAS is the product of a fast ‘through solution’ precipitation, which contrasts with the slower dissolution-precipitation mechanism of a ‘topotactic’ growth of C-S-H in OPC. The chemical and mineralogical characterisation of solid and liquid phases and their changes with time are the basis for thermodynamic modelling of the corresponding hydration process, which is presented in a second paper.

A. Gruskovnjak

B. Lothenbach

L. Holzer

R. Figi

F. Winnefeld

Advances in Cement Research

水泥研究进展突出了尖端水泥制造行业的科学理念和创新。它是一本全球性期刊，范围包括水泥制造和材料、水泥材料和系统的性能和耐久性、水化、水泥与其他材料的相互作用、分析和测试、特殊水泥和应用。

The journal "Advances in Cement Research" focuses on cutting-edge scientific concepts and innovations in the cement manufacturing industry. As a global journal, it covers a wide range of topics including cement production and materials, performance and durability of cement materials and systems, hydration processes, interactions between cement and other materials, analysis and testing, as well as special cements and their applications.

《Advances in Cement Research》期刊专注于水泥制造行业的前沿科学理念和创新。作为一本全球性期刊，其涵盖的范围包括水泥的生产与材料、性能与耐久性、水化过程、水泥与其他材料的相互作用、分析与测试，以及特殊水泥的应用等领域。

Category	Quartile
工程技术	4
工程技术, 结构与建筑技术	4
工程技术, 材料科学综合	4

Hydration of alkali-activated slag: comparison with ordinary Portland cement

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Journal Info

Category	Quartile
MATERIALS SCIENCE, MULTIDISCIPLINARY	4