We investigated the effects of hydrogen-rich water (HRW) on the strength and durability of Portland cement mortars. We comparatively assessed the performances of HRW-based mortars (HWMs) with respect to cement mortars fabricated from control water (CWM). The results indicate that the use of HRW significantly improves the compressive, flexural, and splitting tensile strength of mortars at both the early and later ages of curing. Durability was assessed in terms of capillary absorption, ultrasonic pulse velocity (UPV), dynamic elastic modulus (DEM), and electrical resistivity (ER). We attribute the generally improved mechanical and durability properties of HWMs to the formation of more cement hydrates with fewer voids in the hydrogen-rich environment. Based on X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope (SEM) analyses, we deduce that the use of HRW in Portland cement mortars produces a more compact, dense, and durable microstructure with fewer voids due to a higher degree of hydration.

Increasing demand for cement in the construction industry is posing a serious threat to the environment. This necessitates the utilization of supplementary cementitious materials such as silica fume, fly ash, rice husk ash, and wheat straw ash as a cement replacement material. Additionally, fiber-reinforced cement composites can be efficiently used in repair and rehabilitation works. In this study, we have investigated the performance of fiber-reinforced cement composites blended with wheat straw ash. Wheat straw ash has been proved to be an effective pozzolanic material. Cement was replaced by 20% (weight) wheat straw ash. Polypropylene fibers were added at a dosage of 0%, 0.5%, 1%, and 2% by weight of cement. Mortar specimens were fabricated and investigated for the compressive, flexure, and indirect tensile strengths, ultrasonic pulse velocity, chloride migration resistance, and carbonation resistance. The results demonstrate that the addition of fibers caused a reduction in the compressive strength, pulse velocity, chloride migration resistance, and carbonation resistance; however, flexure and indirect tensile strengths were significantly enhanced. Moreover, the incorporation of fine size wheat straw ash particles compensated the negative effect of fiber inclusion.

In the present case study, the use of an advanced, efficient and low-cost technique for monitoring an urban stream was reported. Physicochemical parameters (PcPs) of Jungnangcheon stream (Seoul, South Korea) were assessed using an Internet of Things (IoT) platform. Temperature, dissolved oxygen (DO), and pH parameters were monitored for the three summer months and the first fall month at a fixed location. Analysis was performed using clustering techniques (CTs), such as K-means clustering, agglomerative hierarchical clustering (AHC), and density-based spatial clustering of applications with noise (DBSCAN). An IoT-based Arduino sensor module (ASM) network with a 99.99% efficient communication platform was developed to allow collection of stream data with user-friendly software and hardware and facilitated data analysis by interested individuals using their smartphones. Clustering was used to formulate relationships among physicochemical parameters. K-means clustering was used to identify natural clusters using the silhouette coefficient based on cluster compactness and looseness. AHC grouped all data into two clusters as well as temperature, DO and pH into four, eight, and four clusters, respectively. DBSCAN analysis was also performed to evaluate yearly variations in physicochemical parameters. Noise points (NOISE) of temperature in 2016 were border points (ƥ), whereas in 2014 and 2015 they remained core points (ɋ), indicating a trend toward increasing stream temperature. We found the stream parameters were within the permissible limits set by the Water Quality Standards for River Water, South Korea.