Abstract
The ferrite aluminate cement (FAC) could rapidly lose fluidity or workability due to its excessive hydration rate, and greatly reduce the construction performance. Chemical admixtures are commonly used to provide the workability of cement-based materials. In this study, to ensure required fluidity of FAC, chemically different water reducing agents are incorporated into the FAC pastes. The experiments are performed with aliphatic water reducing agent (AP), polycarboxylic acid water reducing agent (PC) and melamine water reducing agent (MA), respectively. Influence of the water reducing agents on fluidity, setting time, hydration process, hydration product and zeta potential of the fresh cement pastes is investigated. The results show that PC has a better dispersion capacity compared to AP and MA. Besides decreasing water dosage, PC also acts as a retarder, significantly increasing the setting times, delaying the hydration rate and leading to less ettringite in the hydration process of FAC particles. The water reducing agents molecules are adsorbed on the surface of positively charged minerals and hydration products, however, for PC, steric hindrance from the long side chain of PC plays a critical role in dispersing cement particles, whereas AP and MA acting through an electrostatic repulsion force.
Highlights
As the most important building material, Portland cement has been widely used in engineering construction worldwide
Compared with Portland cement clinker, the CO2 emissions are relatively lower owing to the lower production temperature and lime saturation factor of Calcium sulfoaluminate clinker [6–9]
AP was an anionic surfactant with chain-like molecular structure, containing carboxylate, sulfonate and hydroxyl active groups.The second employed polymer was combshaped PC, which consisted of main backbone with carboxylate groups and side chains
Summary
As the most important building material, Portland cement has been widely used in engineering construction worldwide. Even though red mud and fly ash, which are Al-rich industrial wastes, have been successfully used to produce Calcium sulfoaluminate clinker in the laboratory, drawback of these industrial wastes is their low Al2 O3 content, owing to the high content of SiO2 [15–19] These industrial wastes still can not meet the requirement of aluminum materials in Calcium sulfoaluminate raw meal [14]. Water reducing agents is a kind of important chemical admixture for Portland cement-based materials [24–27]. They can increase the workability of fresh concrete without additional water, or reduce the amount of water for a given fluidity [28–31]. The resultings data of chemically different water reducing agents in FAC can provide a fundamental understanding for the industrial application
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