Effect of Water pH and Waterlogging Depth on the Physical and Mechanical Properties of Concrete Pavement

Abstract

This research examines the combined effect of waterlogging heights and water pH levels on the physical, mechanical, and microstructural properties of concrete pavements. A ready-mix concrete with a compressive strength of 25 MPa was used, with waterlogging heights varying between 0.5 cm and 5 cm and water pH ranging from pH = 2 to pH = 7. After 28 days of curing, testing was performed to measure compressive strength, water absorption, porosity, and microstructural analysis using Scanning Electron Microscope-Energy Dispersive X-Ray (SEM-EDX). It was found that concrete immersed in acidic water at low pH drastically lost its compressive strength at 12.53 MPa compared to concrete immersed in neutral water at 15.92 MPa compressive strength. Concrete immersed in acidic water also showed higher levels of porosity and absorption, indicative of the destruction of the concrete matrix through dissolution of the C-S-H gel and calcium carbonate. The SEM analysis and EDX revealed that concrete exposed to low pH water underwent dissolution of the primary cement phases, causing microstructural changes, and thus possible reduction of concrete durability and mechanical resistance. This provides a new insight into the importance of considering both the height of waterlogging and pH in the design of durable rigid pavement concrete in regions prone to acidic waterlogging.