This study uses neutron radiography (NR) and visual inspection to quantify water penetration in concrete samples exposed to water pressure on one face. It provides experimental data regarding the impact of mixture proportions on the hydraulic permeability of concrete. Specifically, it illustrates the influence of water-cement ratio (w/c), curing duration, entrained air content, and coarse aggregate (CA) size and volume on water transport. In addition, this paper quantifies the impact of permeability-reducing admixtures (PRAs) on water transport in concrete. It was observed that decreasing the w/c and/or increasing the curing duration reduced the fluid transport. Liquid and powder PRAs efficiently reduced fluid transport in concrete without impacting the compressive strength. The liquid PRA showed more consistent results, likely due to better dispersion than the powder PRA. Fluid ingress in concrete samples appears to increase with entrained air content due to a lower degree of saturation (DOS) at the start of the test. Increasing the CA volume fraction or decreasing the CA size will increase the fluid transport in concrete due to an increase in the connectivity of the interfacial transition zone. The influence of entrained air content, curing duration, CA volume fraction, and CA size was less noticeable on mixtures with PRAs due to the higher density and low permeability of these samples compared to control samples.

The improvement of durability and service life of reinforced concrete structures in the marine environment with the incorporation of corrosion inhibitors has attracted significant attention in recent years. The present study aims to evaluate the performance of a commercially available organic corrosion inhibitor in protecting the steel reinforcement of concrete structures in marine conditions. The study was performed on a control mixture and a test mixture with water-cement ratios (w/c) of 0.4 and 0.6, providing aggressive laboratory and field environments following the recommendation of international standards for corrosion inhibitors assessments. Corrosion monitoring methods and visual inspection of reinforcing bars confirmed the effectiveness of migrating corrosion inhibitor in mitigating chloride-induced corrosion. The migratory properties of the corrosion inhibitor and its ability to densify the matrix microstructure were confirmed through scanning electron microscopy and X-ray photoelectron spectroscopy analyses.

In this paper, acid resistance and microstructural properties of cement mortars containing ceramic waste powder (CWP) as an alternative cementitious material were examined. Cement powder was replaced with CWP powder in amounts of 0, 5, 10, 15, 20, and 25% (by weight of cement). The fresh mortars were stored in 100% relative humidity for 1 day then the specimens were cured 28 days in the water. To simulate sulfuric acid deposits, the prepared specimens were submerged in a sulfuric acid solution (pH = 1.5) for 28, 42, and 56 days. This study presents the mechanical strength, visual inspection, and mass loss tests of the cement mortars. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) analyses of prepared mortars were used to explore the specimen microstructures. The results show that the specimens including CWP as cement replacement exhibit higher mechanical strength than control specimens at 28, 42, and 56 days of acid curing. The SEM micrographs illustrated that incorporation CWP as cement replacement decreased the voids and pores. XRD diffractograms explained that the specimens including CWP have lower intensities of gypsum peaks than the control samples. It should be noted that using CWP as cement replacement improves the acid resistance of mortars.

This paper reports the splitting tensile strength of concrete corroded by saline soil. The wet-dry cycle erosion test and splitting tensile test were performed on concrete cubic specimens with six different erosion inspection periods and a solution with the same concentration as the saline soil. The variation of chlorine and sulfate with erosion depth for different erosion inspection periods of corroded concrete, as well as the powder on the concrete within the erosion depth, were analyzed via X-ray diffraction (XRD). Combined with the parallel bar system, corroded concrete specimens were divided into corrosion and non-corrosion parts. Considering the corrosive effect of saline soil on the concrete specimen, the splitting tensile strength model of the corroded concrete in the saline soil area was established and compared with experimental values. The results show that the calculated values of the splitting tensile strength model established herein agreed with experimental values. The splitting tensile strength of concrete gradually decreased with the increasing erosion depth, and the erosion depth gradually deepened with the increasing wet-dry cycle time. This is because CaCO3, ettringite, gypsum, and Friedel’s salts were produced by reacting with concrete in the range of erosion, which resulted in the decrease of splitting tensile strength of concrete.

This study evaluates the acid resistance of cement mortar using granulated ferronickel slag (FNS) as fine aggregate and fly ash or ground FNS (GFNS) as a supplementary cementitious material (SCM). The deterioration was evaluated by visual inspection, and changes of mass and strength after immersion in 1% sulfuric acid solution for up to 180 days. Acid resistance was marginally reduced when 50% volume of sand was replaced by FNS. While the control specimens suffered significant spalling and strength loss, the use of fly ash or GFNS considerably reduced the deterioration. This is attributed to the formation of a protective zone and densification of microstructure by the pozzolanic reaction, as confirmed by strength activity index, permeable voids, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Overall, the specimens with FNS aggregate and GFNS or fly ash showed less deterioration than the control specimens after prolonged acid exposure.