Search

• 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]

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]