Designing a superhydrophobic quality and strengthening mechanism for foam concrete

In this study, a superhydrophobic concrete system was created by modifying the concrete by adding calcium stearate (CS), polydimethylsiloxane (PDMS), and hydroxypropyl methylcellulose (HPMC) and then blending the resultant mixture with foam prepared using an anionic composite foaming agent to achieve superhydrophobic properties. Through the control variable method design experiment, two groups of optimal mix ratios, C3P5H0.125 and C3P8H0.05, were obtained, and the contact angles were 150.4° and 153°, respectively. It was confirmed by Fourier transform infrared spectroscopy that PDMS had bonded to the cement hydration product and dispersed uniformly. The microstructure of the pore surface of foam concrete was observed by scanning electron microscope (SEM), and the surface roughness of the superhydrophobic foam concrete was found to be significantly higher than that of ordinary foam concrete. The density range of the prepared superhydrophobic foam concrete specimens was 500–700 kg/m3, its strength range was 1.5–3.1 MPa, the water absorption rate was as low as 5 %, which was 86 % lower than the highest water absorption rate in the experimental group, and 40 % of all pore sizes was below 200 μm. The prepared foam concrete revealed excellent anti-contamination and self-cleaning properties, abrasion resistance, and chemical stability. Under continuous mechanical wear and harsh environments, the overall superhydrophobicity of the concrete specimens remained stable. With these excellent attributes and an easy production process, the foam concrete prepared in this study offers broad application prospects.