143 / 2022-04-29 11:10:56

Study on preparation and self-healing properties of cement-based materials using prepared autolytic clinker microsphere

Mineral self-healing; Autolytic clinker microsphere; Cement-based materials; Autolytic mechanism

The autolytic clinker microsphere with clinker as core and polyvinyl pyrrolidone (PVP) as coating film was prepared. Pretreatment of clinker with silane coupling agent was firstly processed during the preparation. To investigate the autolytic mechanism, the morphology of autolytic clinker microsphere with hydration going was observed using environmental scanning electron microscopy (ESEM), equipped with energy dispersive spectrometer (EDS). The autolytic stages were also identified based on the microstructural evolution. The chemical structure was characterized by Fourier transform infrared spectroscopy (FTIR). The influence of pretreatment degree on autolytic behavior was also studied by measurements of micro-morphology and iso-thermal calorimetry. Self-healing properties were determined by recovery of compressive strength and damage degree.



Based on the FTIR results, it is confirmed that clinker remains the original mineral healing composition with the coating of PVP film on the clinker surface (Fig. 1). All autolytic clinker microspheres present a similar size distribution to clinker, each having sizes on the order of tens of microns (Fig. 2). The autolytic mechanism of microspheres is explored and autolytic stage is divided into three processes (Fig. 3). The pretreatment of clinker is effective and presents significant improvements in terms of autolytic time (Fig. 4).



The influence of microsphere amount and curing environment on self-healing properties of cement-based materials with autolytic clinker microsphere were also determined. The better self-healing properties of specimens are confirmed by the compressive strength recovery (Fig. 5) and damage degree (Fig. 6) tests with more addition of microspheres. Alkali environmental curing has positive effects on self-healing properties. The alkaline environment improves crack closure (Fig. 7) more effectively than compressive strength (Fig. 8).