Study on early performance of rapid hardening sulphoaluminate cement-based sealing material

In order to develop materials suitable for rapid plugging of concrete leakage defects under pressure, we use vinyl acetate-ethylene copolymer (VAE) to modify rapid hardening sulphoaluminate cement (R·SAC). Employing rheometer, R·SAC’s rheologic property was revealed by testing its viscosity law which varies with time. The early performance of R·SAC-based materials was unveiled by combining the testing results of R·SAC’s mechanical property by means of anti-flexural and anti-pressure test and adhesion test on “8”-shaped model with analysis of scanning electron microscope (SEM). The study shows that maintainable time of initial viscosity of R·SAC is about 40 minutes, whose viscosity surges with exponential rate later. With an addition of VAE, plugging material’s ability to resist leaking water pressure improved accompanied by an increase of R·SAC’s initial viscosity, an acceleration of mutational site and an remarkable leap of viscosity’s growing rate. The most obvious phenomenon above occurs by adding 4% VAE into the material. When the content of VAE ranges from 3% to 4%, the increase of R·SAC’s early anti-flexural strength varies from 15% to 21% and anti-pressure strength decreases accordingly. The increase of flexural-press ratio demonstrates that the flexibility of the modified R·SAC achieves improvement. When the content of VAE reaches 4%, 1 d bonding strength hits its maximum with a 121% bonding strength growth compared with the control group. Analysis from SEM illustrates that dense lap structures are formed among interior granules of R·SAC and thus the material’s ability to plug leakage defects gets substantive progress.