Ceramics-Silikáty 66, (4) 419 - 427 (2022)

In this paper, recycled concrete aggregates and PAC slag were used to prepare concrete. X-ray fluorescence (XRF), X-ray diffraction (XRD) and scanning electron microscope (SEM) were used to analyse the micro-properties of the PAC and the concrete. Furthermore, the effects of the activators on the water absorption, compressive strength and frost resistance of the concrete were studied. The results showed that the effects of the activators on the water absorption were not obvious, but they could improve the activity of the PAC slag, thus, the hydration products in the mortar significantly increased and the micro-structure of the mortar became denser. Furthermore, the compressive strength of the concrete at 28 days increased by 26.5% when the activator was mixed with 3% water glass and 3% sodium sulfate. Moreover, the activators could improve the frost resistance of the concrete. However, when the activators were added in the concrete together, negative effects were found on the frost resistance of the concrete, with a mass loss of 20%.