Development of a sprayable PVA-fiber-enhanced cement mortar with high acid-corrosion resistance for pipeline rehabilitate

Abstract

The spraying method offers the advantages of environmental protection, convenient construction, and cost-effectiveness, making it widely used in pipeline structure repair. Given the complex service environment of pipelines, there is an urgent demand for high-strength and durable spraying materials. To achieve this goal, a PVA fiber reinforced cement mortar material (PFCM) with high early strength, excellent impermeability and stable acid corrosion resistance was developed through orthogonal test design. The optimal material was obtained through factors such as setting time, fluidity, compressive strength and flexural strength. The effects of the contents of fly ash, redispersible polymer powder and PVA fiber on the working and mechanical properties of the material were investigated, and further research was conducted on its tensile strength, impermeability, acid corrosion resistance. In addition, Thermogravimetric-differential Thermal Analysis (TG-DTA) was utilized to analyze the thermal stability of PFCM. X-ray diffraction (XRD) was utilized to analyze the composition of PFCM. Mercury intrusion porosimetry (MIP) was utilized to analyze the pore structure of PFCM, and the feasibility of the PFCM was verified. The results indicate that the contents of fly ash, redispersible polymer powder and PVA fiber have significant effects on the working and mechanical properties. The optimum initial setting time is 60–80 min, and the optimum fluidity is between 170 and 180 mm. The compressive strength and flexural strength of the mortar prepared with the optimum parameters are 102.5 MPa and 20 MPa, respectively. The material has an excellent spraying effect with no sagging, and exhibits high early strength, outstanding corrosion resistance, low porosity, and exceptional impermeability. This study lays the foundation for achieving high-quality spray repairs of underground drainage pipelines.