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This study assesses hydration, rheology, and sorptivity of cementitious pastes using relatively low-cost Arduino-based platforms with integrated sensors. The prime objective is to develop a correlation between conventional apparatus-based and Arduino-integrated sensor-based assessment. A total of six samples of cementitious paste were prepared at a room temperature of 26°C, with a w/b ratio of 0.3, containing cement, fly ash, and silica fume. First, the conventional apparatus was employed to assess hydration, rheology, and sorptivity of cementitious mixes. Afterward, a platform arranged for data acquisition, comprising Arduino Mega 2560, a temperature sensor, a soil moisture sensor, and a voltage supply, was used to assess the same properties. The recorded temperature and moisture content data were transmitted using the Android application and the Wi-Fi modem router. A 5-minute moisture analysis test was conducted to monitor the rheological behavior of cementitious mixes. The heat of the hydration mechanism was evaluated for 32 hours using a temperature sensor, enabling continuous and real-time monitoring. Moreover, a sorptivity test on cube samples was performed using shielded self-based apparatus in an adiabatic condition, resulting in relatively long-term monitoring. The microscopic details are analyzed by using a scanning electron microscope (SEM) in conjunction with EDX analysis. Thus, the potential application of the inexpensive sensor-based method is verified. [ABSTRACT FROM AUTHOR]

This paper investigates the effectiveness of polysaccharide-based biopolymers (natural and semi-synthetic) on the setting time, compressive strength, and microstructural properties of alkali-activated Mn-rich slag pastes. Two types of polysaccharides were used: natural and semi-synthetic. The polysaccharides included gum arabic (GA), guar gum (GG), gum tragacanth (GT), methylcellulose (MC), hydroxyethyl cellulose (HEC), and hydroxypropyl methylcellulose (HPMC). The dosage of polysaccharides was kept constant at 0.1 wt. % relative to the slag. The results indicated that natural and semi-synthetic polysaccharides accelerated and retarded the setting of the alkali-activated slag (AAS) pastes, respectively. All the polysaccharides except for HPMC enhanced the compressive strength compared with the control AAS paste. X-ray diffraction analysis, Fourier transform infrared spectroscopy, scanning electron microscopy, and energy-dispersive X-ray spectroscopy revealed that polysaccharides generally promote the formation of longer silica chains and hydration products. A plausible interaction mechanism explaining the possible mode of action of polysaccharides in AASs is also presented. [ABSTRACT FROM AUTHOR]

Deterioration of asphalt pavements due to massive load of vehicles and climatic variation has demanded the use of pavements construction material with an excellent resilience characteristic, resistance to permanent deformation, and most importantly, a much longer service lifespan. The main structural distresses in pavement construction are permanent deformation at high temperatures and fatigue cracking under repetitive traffic loadings. To comprehensively investigate the performance of bitumen penetration grade (PG) 70 against rutting, fatigue, and high temperature cracking in hot mix asphalt (HMA) pavements, polycarbonate (PC) and polytetrafluoroethylene (PTFE) were used. The investigation of the internal structure, rheological, and physical properties of base and modified bitumen (MB) mixes with different percentages of modifiers (0%, 2.5%, and 5%) by weight were performed via scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) analysis, X-ray diffraction (XRD) pattern analysis, rolling thin-film oven test (RTFOT), pressurized aging vessel (PAV), dynamic shear rheometer (DSR), rotational viscosity (RV), and bending beam rheometer (BBR). The results of the RV test indicate that modification of neat bitumen with polycarbonate and polytetrafluoroethylene increased the viscosity for polycarbonate-modified bitumen (PCMB), polytetrafluoroethylene-modified bitumen (PTFEMB), and for a blend of PCMB-PTFEMB by 44%, 50%, and 55.75% at 135 °C and 111.10%, 127.80%, and 138.88% at 165 °C, accordingly. BBR test results revealed that modifiers increased the rigidity of neat bitumen by 74.8%, 75.8%, and 74.5% at −16 °C, −22 °C, and −28 °C, respectively. [ABSTRACT FROM AUTHOR]

This study investigates the protective effect of various hydroxy acid-based rust converters such as malic acid, tartaric acid, lactic acid, hydroxy acid mixture and glycolic acid in controlling the corrosion of steel reinforcement embedded in cement mortar. The steel rebars pre-treated with hydroxy acids were embedded in cement mortar samples. Afterward, the reinforced samples were exposed to 2.5% sodium chloride (NaCl) and 2.5% magnesium sulphate (MgSO4) solution for 52 weeks (∼365 days). The corrosion state of rebars was estimated in terms of visual assessment of steel rebars, electrical resistivity (ER), corrosion current density based on linear polarisation resistance (LPR) and half-cell potential (HCP) values. The results indicate that the rebar specimens treated with malic, tartaric, lactic and hydroxy acid mixture underwent a lower degree of corrosion-related deterioration. This inhibition effect on the corrosion of steel rebars is due to the formation of insoluble complexes and chelates, leading to the preservation of hydration products in the samples collected from the steel–mortar interface as evidenced by SEM, XRD and FTIR spectroscopy. [ABSTRACT FROM AUTHOR]

• Chemical durability of superabsorbent polymers based geopolymer mortars was assessed. • Superabsorbent polymers based geopolymer mortars offered good resistance to acid, sulfate, and chloride attack. • Using superabsorbent polymer offers a protective effect on the microstructure of geopolymer mortars. • Use of superabsorbent in geopolymers demonstrated a greater degree of geopolymerization. This study investigates the durability of superabsorbent polymer (SAP) based geopolymer mortars (GPMs) against acid, sulfate, and chloride attack. Nine mix formulations containing 0, 1, and 2% SAP content by weight of fly ash were prepared. All the samples were cured at 80 °C, followed by curing at room temperature for 24 h. The specimens were immersed in the chemical solutions of 5% hydrochloric acid (HCl), 5% sodium sulfate (Na 2 SO 4), and 5% calcium chloride (CaCl 2) for 180 days. Thereafter, the durability performance of GPMs was evaluated based on the change in weight and change in compressive strength of the specimens. Based on the results, it was deduced that SAP based GPMs were less vulnerable to chemical attack. Furthermore, deterioration effects were lower due to improved sorptivity and porosity values. The X-ray Diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscope (SEM), and Energy Dispersion X-ray Spectroscopy (EDX) analyses revealed that the inclusion of SAP improves the chemical durability of GPMs. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The present article illustrates the acid and sulfate resistance performance of control (CM) and the hydrogen-rich water-based mortar (HM) samples. The 28 days cured CM and HM samples were exposed to 5% HCl, 5% HNO 3 , and 5% sodium sulfate solutions for 30, 60, 90, 120, 150, and 180 days to evaluate their acid and sulfate resistance performances. The impact of acid and sulfate attack was evaluated measuring the weight and compressive strength loss of mortar samples in the different exposure regimes. Additionally, water absorption, porosity, and sorptivity tests were performed to evaluate the transport properties of the mortars. Analyzing the result, a lesser extent of compressive strength loss (47.63% in HCl, 39.47% in HNO 3 , and 3% in Na 2 SO 4 ) was observed for the hydrogen-rich water-based mortar as compared to that of the control mortar (57.33% in HCl, 55.4% in HNO 3 , and 14% in Na 2 SO 4 ) after 180 days exposure. Based on the X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy analysis, a plausible mechanism has been proposed to explain the beneficial effect of the hydrogen-rich water-based mortars against acid and sulfate attacks. [ABSTRACT FROM AUTHOR]

• Portland cement pastes were produced using water resistant SiO 2 coated SrAl 2 O 4 : Eu2+, Dy3+ (SSA) phosphor. • SSA phosphor accelerates the cement hydration and improves compressive strength. • Analytical characterization of SSA phosphor based cement pastes through SEM, XRD, EDX, TG-DTG, and FTIR. • SSA phosphor based cement pastes demonstrated persistent luminescence. The present study investigates the effect of water-resistant SiO 2 coated SrAl 2 O 4 : Eu2+, Dy3+ (SSA) phosphor on the properties of Portland cement pastes. In order to investigate it, firstly, SrAl 2 O 4 : Eu2+, Dy3+ phosphor was coated with SiO 2 using heterogeneous precipitation method. Afterward, coated phosphor was admixed with Portland cement in varying proportions to prepare cement pastes. The setting time, hydration reaction, compressive strength, and luminescence intensity analysis were carried out. Moreover, water resistance performance of SSA phosphor based cement pastes was assessed in terms of afterglow test. Based on the results of setting time and hydration studies, it was deduced that SSA phosphor has set acceleration effect on cement pastes. Use of SSA phosphor improved the compressive strength of cement pastes due to the greater degree of hydration. Moreover, the afterglow study results confirmed the hydrolysis stability of SSA phosphor in water cured cement pastes. The XRD, SEM, EDX, TG-DTG, and FTIR analyses confirmed the formation of excessive amount of hydration products in SSA phosphor based cement pastes. Based on the results obtained, it is concluded that using SSA phosphor could be a promising approach for producing water-resistant persistent luminescence light emitting cement composites. [ABSTRACT FROM AUTHOR]

This research assessed the mechanical performance, gamma-ray shielding, and interfacial transition zone (ITZ) microstructural properties of concrete mixes that incorporate barite coarse aggregates and nanosilica. To achieve this goal, several concrete mixes containing normal coarse aggregate (NC), barite aggregate (BC), and nano-silica/barite aggregates (NSBC) were fabricated. Several properties such as workability, mechanical strength, electrical resistivity (ER), ultrasonic pulse velocity (UPV), chloride migration (RCPT), and gamma shielding were comparatively assessed for these concrete mixtures. In addition, analytical characterizations viz., x-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electronic microscopy (SEM), and energy dispersive x-ray (EDX) were employed to study the ITZ microstructure at mortar/aggregate interface of concrete mixtures. The results showed that barite concrete incorporating nanosilica (NSBC) exhibited higher density and improved mechanical properties compared to both normal concrete (NC) and barite concrete (BC). Specifically, concrete mixture containing barite aggregate and 3% nanosilica (3NSBC) content exhibited improved impermeability and reduced concrete porosity. The gamma-ray shielding properties for 3NSBC were superior among all concrete mixtures. After 28 days, 3NSBC exhibits higher compressive strength (18.26% and 14.76%) and greater shielding capacity (12.82% and 6.66%) compared to NC and BC, respectively. The analytical characterizations results have demonstrated that nanosilica helps prevent the accumulation of calcium hydroxide in the ITZ by utilizing it to form calcium silicate hydrate. This leads to the development of a more compact and denser microstructure in the ITZ of nano-silica-based barite concrete (NSBC). Furthermore, it was revealed that, the incorporation of nanosilica exceeding 3% led to agglomeration, resulting in a weaker ITZ within the concrete leading to overall reduction in concrete properties. • Fabricated normal (NC) and heavyweight concrete with/without nanosilica (NSBC and BC). • ITZ microstructure analyzed using SEM/EDX, XRD, and FTIR. • NSBC showed improved physical and mechanical properties. • Exceptional nuclear shielding performance observed for NSBC. [ABSTRACT FROM AUTHOR]

The present investigation deals with the effectiveness of hydrogen-rich water in controlling the physical and mechanical performances of cement mortar. In this study, the different concentrations of hydrogen-rich water (0.2, 0.3, 0.4, and 0.5 ppm) were used to fabricate the mortar samples. The impact of the hydrogen-rich water was evaluated analyzing the setting time, flow table value, bulk density, water absorption, apparent porosity, compressive strength and flexural strength of the cement mortar samples. Analyzing the results, the final setting time of the control, as well as 0.5 ppm hydrogen-rich water based cement, is measured to be 257 ± 3 min and 14 ± 3 min, respectively. Additionally, the compressive as well as flexural strength of 7 days cured 0.5 ppm hydrogen-rich water based cement mortar is found to be 59% and 30% higher, respectively, as compared to that of the control mortar. This could be primarily governed by the formation of the greater extent of hydrated cement product in the presence of hydrogen-rich water. Therefore, it is demonstrated that the hydrogen-rich water behaves like a cement set accelerator admixture. Finally, a model has been proposed to explain the overall performances of hydrogen water based cement mortar. [ABSTRACT FROM AUTHOR]

In this study, pristineMnO2 catalystwas synthesized by hydrothermal technique and annealed at 400 and 600°C (MnO2@400°C and MnO2@600°C) transforming it into nanorods in a nitrogen atmosphere. The heat treatment process ameliorates the catalytic activity of the MnO2 catalyst by inducing oxygen vacancies. The catalyst is characterized by scanning electron microscope, and X-ray diffraction, Fourier transforms infrared spectroscopy (FTIR), Electron paramagnetic resonance (EPR), and X-ray Photoelectron Spectroscopy, whereas the oxygen reduction reaction (ORR) activity examined through rotating disc electrode and fuel cell test station. To elucidate the effect of sintering temperature on the MnO2 nanorods, the high angle annular dark-field (HAADF) imaging was carried out on the samples. MnO2@400°C showed preeminent robustness to withstand austere alkaline environment during the experiment and possessed high electrocatalytic activity for the ORR with current density and onset potential values of 6.4 mA cm-2 and 0.80 V VS (RHE), respectively. The single-cell test experiment of alkaline fuel cell delivered peak power density 81 mW/cm at 50°C. It is believed that this idiosyncratic behavior of MnO2 nanorods is due to the preferential growth on (211) and (310) indices and coexistence of optimized Mn4+/Mn3+ oxidation states as well as the creation of optimum oxygen vacancies on MnO2 nanorods. Moreover, the stretching of MnO2 nanorods occurs with increasing temperature and thus increasing the surface area to volume ratio. Thus thermal treatment shows thatMnO2 is highly sensitive toward temperature variation and optimum ORR results can be obtained at adequate temperatures. [ABSTRACT FROM AUTHOR]