Hydration Period Research Articles

A novel quantitative particle distance estimation method of low water/binder cementitious composites (LW/B-CC): Modeling and verification

This paper intends to employ water film theory and 1H Low-field NMR (Lf-NMR) to quantitatively evaluate the particle packing state of low water/binder cementitious composite (LW/B-CC) at different scales. The specific approach involves establishing particle distance models to evaluate the macroscopic, mesoscopic, and microscopic particle packing states of LW/B-CC samples using water film theory and Lf-NMR. The results indicate that Macro_PD is positively related to the product of plastic viscosity and distance of aggregate segregation, Meso_PD shows negatively related to the elastic modulus of ITZ. And Micro_PD can indicate different hydration period. Finally, a multiple linear regression analysis is used to establish a quantitative relationship between PD of different scales and compressive strength. The established particle distance models at different scales are proved to have significant guiding implications for various properties of LW/B-CC. This study presents a novel evaluation method for the particle packing state and provides guidance for the mix design of LW/B-CC.

Mechanical properties and hydration mechanism of nano-silica modified alkali-activated thermally activated recycled cement

The recycling and reuse of waste concrete are crucial for reducing environmental pollution, minimizing resource waste, and lowering carbon emissions. However, current efforts to improve the performance of recycled cement (RC) using the synergistic effects of alkali activation and thermal activation have been suboptimal. Therefore, this study explores the influence of nano-silica (NS) incorporation on the mechanical properties and hydration mechanism of alkali-activated and thermally activated RC. The research focuses on cement mortar with a thermal activation temperature of 750°C, an RC replacement rate of 30%, and an alkali content of 6%. Various analytical techniques, including thermogravimetric analysis (TG-DTG), X-ray diffraction (XRD), and scanning electron microscopy (SEM), were used to evaluate the impact of different NS dosages (1%, 2%, 3%, and 5%) on the mechanical properties and hydration characteristics of nano-modified alkali-activated and thermally activated RC mortar. The study reveals the mechanism by which NS enhances the microstructure of alkali-activated and thermally activated RC. The experimental results show that as the NS content increases, the compressive and flexural strengths of RC initially increase and then decrease. The optimal strength was achieved with a 2% NS content, with a 31.5% increase in compressive strength compared to RC without NS. At this dosage, RC exhibited a higher hydration rate during the acceleration period of hydration. Additionally, the initial hydration heat release rate of RC increased with rising NS content. While NS incorporation did not alter the phase composition of RC, it activated the pozzolanic effect of RC, causing free active substances such as CaO and gypsum in the components to dissolve and react to form Aft at the start of the hydration reaction. The unsaturated bonds (≡Si-O- and ≡Si-) on the surface of NS absorbed Ca2⁺ and OH⁻ from the RC, promoting the hydration of C2S and C3S. However, excessive NS content (greater than 3%) led to a decline in RC strength and the formation of more cracks. This is primarily due to the excess NS particles not contributing to an increase in effective nucleation sites, causing agglomeration, an increase in large pores, and a reduction in transition and gel pores, which negatively affected the microstructure and thus reduced the mechanical properties of the RC. Our findings enhance the understanding of the role of nanomaterials in alkali-activated RC and provide valuable insights for further research into high-performance recycled cement materials.

Hydration behavior and thermodynamic modelling of ferroaluminate cement blended with steel slag

This study investigates the effect of steel slag (SS) content on hydration of ferroaluminate cement (FAC). The physical and mechanical properties, hydration properties and microstructure of the cement paste mixtures were also evaluated. The results reveal that the setting time initially shortens and then prolongs while the fluidity, electrical resistivity at 24 h, and chemical shrinkage at 3 days decrease with the increase of SS from 0 % to 30 %. In addition, the analysis of hydration products shows that the incorporation of SS promotes the growth of strätlingite in the SS-FAC paste, which is responsible for strength recovery of FAC at a late period. The compressive strength of the paste with 20 % SS at 90 days exceeded that of the control group. The addition of a small amount (≤20 %) of SS can improve the pore distribution of the SS-FAC paste and have a certain improvement effect on its microstructure in the late periods of hydration. Thermodynamic modelling shows that the growth of AFt and strätlingite (C2ASH8) in the SS-FAC paste is promoted, which is consistent with the experimental results.

Influence of Early Hydration Process on the Hydrostatic Pressure Change of Cement Pastes at Different Temperatures.

In cementing operations, a rapid decrease in the hydrostatic pressure of cement paste is one of the main causes of early gas channeling. In response to this issue, tests were conducted on the variation in the hydrostatic pressure of cement paste over time at different temperatures (30 °C-180 °C), and it was found that the curve of its rapid decrease time point with temperature change conforms to the Boltzmann function. The relationship between the early hydration process and the microstructure of paste at 90 and 150 °C, as well as the changes in hydrostatic pressure, was studied using X-ray powder diffraction, thermogravimetry, and scanning electron microscopy. The results show that the hydrostatic pressure curve of the paste shows a trend of first stabilization and then rapidly decreasing at medium and low temperatures (30 and 90 °C). At high temperatures (150 °C), the pressure curve initially increases until stabilization, enters a stable period, and finally rapidly decreases. In the early stage of hydration induction, there is a large amount of free water between hydration products, and the hydrostatic pressure of the paste remains stable. In the process of hydrostatic pressure reduction, the microstructure of the paste develops from the particle hydration products to a "gel framework", which isolates the pressure transfer of part of the free water. During the acceleration period of hydration, the hydration products enhance the "framework" and reduce the porosity of the paste, completely cutting off the transmission of water pressure, resulting in a rapid decrease in the hydrostatic pressure of the paste. A method for predicting the rapid decrease in hydrostatic pressure of the paste was proposed using the hydration reaction process.

Effect of nano-metakaolin on the early-age fracture properties of cement mortar

In this paper, the fracture performance of nano-metakaolin (NMK) cement mortar during early hydration period was investigated. Different NMK contents (0 %, 3 %, 5 %, 7 %) were considered, and three-point bending tests were conducted. The digital image correlation technology and acoustic emission technology were utilized to analyze P-CMOD curves, initial fracture toughness, unstable fracture toughness, fracture energy, cumulative AE hits, and cumulative AE energy, AE source locations of cement mortar at early hydration stages. Furthermore, SEM experiments were utilized to analyze the mechanism by which NMK affects fracture performance of cement mortar. The results indicate that the incorporation of NMK enhances the fracture properties of cement mortar, with the most suitable NMK content being 5 %. The addition of NMK increases the cracking load, peak load, and the CMOD at the peak load of the cement mortar at 3 d, 7 d, and 14 d. The cracking load and fracture energy of the cement mortar with 5 % NMK increase by 22.5 % and 35.7 % respectively, compared to ordinary cement mortar at 14 d. NMK enhances the initial fracture toughness and unstable fracture toughness of the cement mortar, improving its crack propagation resistance. The unstable fracture toughness of the cement mortar is the largest when the NMK content is 5 % at 14 d, which is 31.6 % higher than that of ordinary cement mortar. Furthermore, NMK increases the cumulative AE energy and fracture energy of the cement mortar, increasing the cumulative ring counts and cumulative AE hits, causing the crack propagation path to deviate and resulting in improved crack resistance. The cumulative ring counts and AE hits for the cement mortar with 5 % NMK are 42.9 % and 66.2 % higher, respectively, than those for ordinary cement mortar at 14 d. NMK significantly modifies the cement matrix, thereby enhancing the fracture resistance of cement mortar.

Study on the influence of nano-silica substitution of reactive Si on the properties and hydration process of alkali-activated cementitious materials paste

Nano-silica (NS) is one of the most commonly used nanomaterials in alkali-activated materials (AAMs). Differing from other inactive nanoparticles, as an active Si source, the pozzolanic activity of NS has a significant effect on the hydration reaction and properties of alkali-activated materials. In this study, activated Si in the activator was replaced by NS to prepare alkali-activated slag/fly ash cementitious materials. The effects of different dispersion methods (dry-mix (MD), water dispersion (WD), and activator dispersion (AD)) of NS on the fluidity, rheological properties, and setting time of fresh pastes were investigated. Effects of NS and reactive Si in the activator on the hydration process of alkali-activated slag/fly ash paste were investigated using isothermal calorimetry and the Krstulović-Dabić hydration model. ICP-OES was utilized to study the changing behavior of the composition of the fresh paste pore solution during the hydration reaction. The results show that ions in the pore solution change continuously with the hydration time and eventually stabilize. The stabilized pore solution is mainly composed of OH- and Na+. Different NS dispersion methods have significant effects on paste workability, rheology, and setting time. Activator dispersion can elevate the content of active Si in the activator, causing changes in the hydration process of the paste, especially for the initial hydration period. NS has the most significant effect on the hydration process due to its pozzolanic activity compared to nucleation and filling effects. The Krstulovic-Dabic model can roughly simulate the hydration kinetics possessed of alkali-activated NS/slag/fly ash after entering the accelerated period.

Effect of pre-hydrated CAC suspensions on the hydration behavior of CAC pastes

The relatively low hydration rate of calcium aluminate cement (CAC) at 15–35 °C leads to retarded setting time and reduced production efficiency of CAC-bonded castables. To accelerate the hydration rate of CAC within this temperature range, the present work proposes the fabrication of nano-hydrates acting as seeds by pre-hydration of CAC in suspensions. CAC powders are dispersed in water with water-to-solid ratio of 4.5 and stirred for varying durations at 25 °C to achieve different pre-hydration degrees. Then the pre-hydrated CAC suspensions replace a small part of cement in the pastes. The influence of the CAC suspensions addition on the hydration heat release and strength development of fresh CAC pastes at 25 °C is investigated. The results indicate that nano-scale hydrates C2AH8 and AH3 form on the surface of pre-hydrated CAC particles in the suspensions and grow rapidly with the extension of stirring duration. The presence of nano-scale hydrates in the pre-hydrated CAC suspensions is found to shorten the induction period of CAC hydration and thus be beneficial to the accelerated hardening of CAC pastes. The pre-hydrated CAC suspension stirred for 3.5 h has the most significant effect on enhancing early strength of the CAC pastes. At this stage, the pre-hydrated CAC within the suspension is in the accelerated period, and has just begun to precipitate large amounts of nano-scale C2AH8 and AH3 acting as seeds to catalyze the hydration and refine the pore structure of CAC pastes.

Investigating correlations between microstructural characteristics and mechanical properties of coral sand mortar with different silica fume contents

The use of coral sand in concrete and mortar for ocean engineering has led to significant reductions in construction costs and improved construction efficiency. However, this approach poses challenges such as low strength, high brittleness, and high porosity. To address these challenges, this study incorporated silica fume to enhance the mechanical properties of the mortar and investigated the effects of different silica fume contents on the hydration process, pore structure, and strength of coral sand mortar. Additionally, this study introduced a novel iterative approach combining low-field nuclear magnetic resonance and scanning electron microscopy image analysis to determine transverse relaxivity (ρ2). During the early hydration process, the intensity spectrum of coral mortar exhibited three peaks at 298, 1841, and 299 au, corresponding to transverse relaxation times (T2) of 0.64, 6.83, and 83.10 ms, respectively. Over a 6 h hydration period, the spectrum of the specimen prepared with white cement exhibited an additional peak that gradually merged with the main peak. As the curing period extended from 7 to 28 days, the porosity of coral sand mortar decreased by 3.77–4.55 %, while the strength increased by 7.43–14.35 MPa across silica fume contents ranging from 6 % to 24 %. With increasing silica fume content, the calcium–silicon ratio of the samples gradually decreased, promoting the formation of more floccus C–S–H gels. Consequently, the sample porosity first decreased slightly. After 28 days of curing, the coral sand mortar containing 12 % silica fume exhibited the highest strength owing to the increased amount of floccus C–S–H gels. These gels gradually filled the pores between the fibrous C–S–H gels, forming a compact spatial reticular structure. This structure mitigated the adverse impact of high porosity on mortar strength.

Effect of interface properties between functionalized cellulose nanocrystals and tricalcium silicate on the early hydration mechanism of cement

The hydration process is a critical stage in the development of the properties of cement-based materials，however, the influence of cellulose nanocrystals (CNC) on cement during the early hydration is controversial. This study uses pure tricalcium silicate (C3S) as the object to analyze the influence of carboxyl CNC (CCNC) and sulfonic CNC (SCNC) on hydration parameters such as hydration rate, types, quality, and pore structure of hydration products during the early hydration period. The dissolution of C3S and the interaction between fluids and minerals at the C3S/CNC interface is the core mechanism of the early hydration. Ultraviolet and energy spectrum analyzed adsorption between CNC and C3S from a physical perspective, and molecular dynamics simulations deeply discussed the adsorption behavior between C3S/Water/CNC at nano-scale. The results show that CNC prolongs the hydration induction and acceleration period, delays the early hydration of C3S; CCNC exhibits a more significant effect than SCNC. Under the action of Ca-O and hydrogen bonds, CNC will adsorb on the surface of C3S and cover its surface, reducing the number of waters on the surface of C3S. Hydrophilic CNC molecules attract water molecules close to the CNC chain, and solidifying water molecules prevents it from entering the hydration surface. CNC also restricts the diffusion of Ca2+ on the surface of C3S to outside, improving the stability of Ca-O coordination, promoting the accumulation of hydration products at the C3S surface, and inhibiting the dissolution of C3S. Understanding the effect of functionalized CNCs on the diffusion and sedimentation mechanism of water molecules and Ca2+ during hydration can provide insights for guiding the design of nanomaterials with strong compatibility with cement systems and enlarging the application of functionalized nanomaterials in cement-based materials engineering fields.

Factors influencing the hydration kinetics of ye'elimite; effect of free lime

This study investigates factors influencing the hydration of ye'elimite, comparing stoichiometric ye'elimite-rich clinkers with and without free lime (Y-C and Y, respectively). Although the hydration sequences and products were similar, there were notable differences in their kinetics. Y-C exhibited rapid hydration upon contact with water, followed by a significant slowdown within minutes. Contrary, Y demonstrates a slower early hydration, but reached the main hydration period earlier and proceeded more rapidly thereafter. Solution analyses revealed higher initial calcium and aluminium concentrations for Y-C, while the sulfur concentration was reduced. This was attributed to the rapid dissolution of free lime, along with some ye'elimite, resulting in the instantaneous formation of ettringite and aluminium hydroxide. Consequently, the solution composition was altered, causing delayed onset of monosulfate formation and main hydration period. These findings contribute to understanding the hydraulic reactivity of ye'elimite and its potential implications for cement production processes.

Fundamental effects of using power ultrasound to accelerate C3S hydration

Activation of cement hydration accelerates hardening of concrete, enables faster production rates or production at similar frequency but significantly reduced CO2 emissions. The present study sheds light at the reason for accelerated cement hydration when power ultrasound (PUS) is applied during mixing.The investigations analysed the effect of PUS on dissolution of tricalcium silicate (C3S), homogeneous precipitation of C-S-H as well its effect on C3S-hydration. A combination of analytical techniques such as electric conductivity, optical emission spectroscopy, thermogravimetry, conduction reaction calorimetry, scanning electron microscopy and specific surface analysis were applied. It was revealed that PUS has a significant effect on paste hydration, which is induced by heterogenous nucleation of C-S-H and CH immediately after sonication. These hydrates were formed and dispersed by sonication thus acting as in-situ formed crystal seeds which shorten the induction period of C3S hydration.

Retardation mechanism of phosphogypsum in phosphogypsum-based excess-sulfate cement

The effect of phosphogypsum (PG) on the hydration and retardation mechanism of phosphogypsum-based excess-sulfate slag cement (PESC) was mainly investigated. Based on the natural characteristics of PG, such as low pH value and the presence of soluble phosphorus impurities, the content of PG passing the 4.75 mm standard sieve was used as a variable to study the retardation mechanism of PG on PESC. It can be inferred from the heat flow and cumulative heat flow that the induction period is significantly prolonged with the content of PG, which is also reflected in the increase of the setting time of PESC. In the early period of hydration, as the content of PG increases, the soluble phosphorus concentration increases, and the pH value decreases. The changes in soluble phosphorus concentration and pH value affect the microstructure and amount of hydrates. Combined with experimental results, it has been demonstrated that the delay in the hydration of PESC by PG content is mainly due to: the excessive dissolution of Ca2+ and SO42- promotes the recrystallization of dihydrate gypsum; the dissolution of soluble phosphorus reduces the pH value in the pore solution and forms precipitates of calcium phosphate and hydroxyapatite; in the initial reaction period, a large amount of ettringite and C-S-H gel precipitate to form a protective film; the decrease in pH value leads to a decrease in carbonization resistance, and CO2 in the air is more likely to attack the PESC paste, react with alkaline substances in PESC, or degrade hydrated C-S-H and ettringite. The above factors all lead to a decrease in exchangeable ions during the hydration, thereby prolonging the setting of PESC.

Study on the performance of alkali-activated phosphorus slag cemented paste backfill material: Effect of activator type and amount

Effective disposal of phosphorus slag (PS) is crucial for ecosystem protection. Herein, this study proposed that Na2SO4 (SS), Na2SiO3 (NS), Na2CO3 (SC) and NaOH (NH) were performed to prepare alkali-activated phosphorus slag cemented paste backfill material (AAPS-PB). The evolution mechanisms of setting time, rheological behavior and mechanical properties at different contents of various activators were systematically investigated. The mineral compositions, bonding structure, micromorphology and pore structure characteristics of AAPS-PB hydration products were further clarified by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) and mercury intrusion porosimeter (MIP). Results indicated that activators were proved to significantly promote the dissolution of PS at appropriate content. NH had stronger alkali activation ability in the early hydration period, whereas NS sufficiently improved the later strength, enhanced the denseness of hydration products and refined the pore structure characteristics. This study expands the avenues for high-value applications of PS.

Study on the hydration characteristics of steel slag cement

The direct use of stainless steel slag in cement presents potential weaknesses in terms of strength and the risk of cracking, which limits its large-scale utilization. Therefore, it was crucial to explore the use of stainless steel slag in clinker cement. In this study, the hydration characteristics of stainless steel slag cement (SS) and ordinary Portland cement (OPC) were compared and analyzed using isothermal calorimetry, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TG-DTG), scanning electron microscopy (SEM), and heavy metal leaching tests. The study investigated the hydration heat, compressive strength at curing ages of 1d, 3d, 5d, 7d, and 28d, hydration products, and safety aspects of SS and OPC. Results showed that the optimum calcination temperature of stainless steel slag cement (SC) and Portland cement (PC) are 1350℃ and the holding time is 2 h. The clinker composition of the two is similar. The main minerals are dicalcium silicate (C2S), tricalcium silicate (C3S), tricalcium aluminate (C3A) and aluminum ferrite tetracalcium (C4AF). Compared with OPC, SS shows a delayed heat release peak during hydration. SS exhibited a delayed exothermic peak in the heat release during hydration compared to OPC. Furthermore, during the stable hydration period, SS produced more calcium aluminate-type solid solution, tightly encapsulating the crystal surface, and exhibited lower heat release. With an increase in curing age, the contents of acicular ettringite (AFt), C-S-H gel, and hexagonal calcium hydroxide (CH) gradually increased in both SS and OPC. Due to higher contents of C4AF, C3S, and C2S in SS, it produced more AFt and C-S-H than OPC. The compressive strength of both SS and OPC increased with curing age, reaching 55.4 MPa and 42.4 MPa at 28 days, meeting the requirements of the national standard (GB/T 21372-2008) in terms of initial and final setting times and f-CaO content. Additionally, heavy metal leaching and soluble Cr6+ tests indicated that their use is safe.

Magnetic resonance elastography resolving all gross anatomical segments of the kidney during controlled hydration.

Introduction: Magnetic resonance elastography (MRE) is a non-invasive method to quantify biomechanical properties of human tissues. It has potential in diagnosis and monitoring of kidney disease, if established in clinical practice. The interplay of flow and volume changes in renal vessels, tubule, urinary collection system and interstitium is complex, but physiological ranges of in vivo viscoelastic properties during fasting and hydration have never been investigated in all gross anatomical segments simultaneously. Method: Ten healthy volunteers underwent two imaging sessions, one following a 12-hour fasting period and the second after a drinking challenge of >10mL per kg body weight (60-75min before the second examination). High-resolution renal MRE was performed using a novel driver with rotating eccentric mass placed at the posterior-lateral wall to couple waves (50Hz) to the kidney. The biomechanical parameters, shear wave speed (cs in m/s), storage modulus (Gd in kPa), loss modulus (Gl in kPa), phase angle and attenuation (α in 1/mm) were derived. Accurate separation of gross anatomical segments was applied in post-processing (whole kidney, cortex, medulla, sinus, vessel). Results: High-quality shear waves coupled into all gross anatomical segments of the kidney (mean shear wave displacement: 163 ± 47μm, mean contamination of second upper harmonics <23%, curl/divergence: 4.3 ± 0.8). Regardless of the hydration state, median Gd of the cortex and medulla (0.68 ± 0.11kPa) was significantly higher than that of the sinus and vessels (0.48 ± 0.06kPa), and consistently, significant differences were found in cs, , and Gl (all p < 0.001). The viscoelastic parameters of cortex and medulla were not significantly different. After hydration sinus exhibited a small but significant reduction in median Gd by -0.02 ± 0.04kPa (p = 0.01), and, consequently, the cortico-sinusoidal-difference in Gd increased by 0.04 ± 0.07kPa (p = 0.05). Only upon hydration, the attenuation in vessels became lower (0.084 ± 0.013 1/mm) and differed significantly from the whole kidney (0.095 ± 0.007 1/mm, p = 0.01). Conclusion: High-resolution renal MRE with an innovative driver and well-defined 3D segmentation can resolve all renal segments, especially when including the sinus in the analysis. Even after a prolonged hydration period the approach is sensitive to small hydration-related changes in the sinus and in the cortico-sinusoidal-difference.

A Eutectic Mixture of Calcium Chloride Hexahydrate and Bischofite with Promising Performance for Thermochemical Energy Storage

Thermochemical energy storage using salt hydrates is a promising method for the efficient use of energy. In this study, three host matrices, expanded vermiculite, expanded clay, and expanded natural graphite were impregnated with a eutectic mixture of CaCl2·6H2O and bischofite (MgCl2·6H2O). These composites were subjected to various humidity conditions (30–70% relative humidity) at 20 °C over an extended hydration period to investigate their cyclability. It was shown that only expanded natural graphite could contain the deliquescent salt at high humidity over 50 cycles. Hence, the expanded natural graphite composites containing either CaCl2·6H2O or CaCl2·6H2O/bischofite eutectic mixture were placed in a lab-scale open packed bed reactor, providing energy densities of 150 and 120 kWh/m3 over 20 h, respectively. The eutectic composite showed slightly lower temperature lift, water uptake rate, and power output but at reduced cost. Using the eutectic mixture also decreased the composite’s dehydration temperature at which the maximum mass loss rate occurred around 16.2 °C to 62.3 °C, allowing recharge using less energy-intensive heating methods. The cost of storing 1 kWh of energy with expanded natural graphite composites is only USD 0.08 due to its stability. This research leveraging cost-effective composites with enhanced stability, reaction kinetics, and high thermal energy storage capabilities benefits renewable energy, power generation, and the building construction research communities and industries by providing a competitive alternative to sensible heat storage technologies.

Early age hydration behaviour of foam concrete containing a coal mining waste: novel experimental procedures and effects of capillary pressure

Globally, coal mining wastes (CMWs) are associated with significant environmental and economic costs. Processing CMW into an ingredient of foam concrete is a promising solution but the behaviour of this particular construction material has not been sufficiently evaluated, especially during the initial period of cement hydration. The purpose of this paper is to present novel laboratory set-up and experimental procedures designed to investigate the early age behaviour of hydrating foam concrete samples made with a CMW from Poland. Two types of tests were devised to simulate air-curing conditions and water-curing conditions, respectively. These tests were carried out in custom-built unsaturated oedometer cells, and the matric suction in the test samples was monitored for approximately 14 days, using Warwick high capacity tensiometers. Experimental results show that in both curing conditions, a higher matric suction during cement hydration corresponds to a denser sample at the end of the monitoring period. A comparison of water-cured and air-cured samples also reveals different responses to CMW inclusion in their mix designs. The responses can be convincingly explained based on complementary test data and idealised capillary tube models adapted for the hydrating foam concrete samples.

O-14 A rare case of hypercalcaemia in pregnancy

Abstract Introduction Hypercalcaemia is infrequent during pregnancy, but it is associated with foetal and maternal morbidity and mortality. Although primary hyperparathyroidism (pHPT) accounts for the majority of the cases, other aetiologies such as genetic causes in a young population should be considered. Clinical Case A 27-year-old female was diagnosed with pHPT during her 16th week of gestation after she presented with vomiting and was found to have raised adjusted calcium of 3.22 mmol/L, low phosphate of 0.6 mmol/L and Parathyroid Hormone of 10.6 pmol/L. The patient's hypercalcaemia dated back 2 years, she had a history of three previous miscarriages, and was not on any hypercalcaemia-inducing medications. Unbeknownst to her, her father was also being evaluated for hypercalcaemia. Her thyroid-stimulating hormone was fully suppressed with raised free thyroid hormones and negative TSH receptor antibodies; this was improved with Carbimazole therapy. Plasma and urine Metanephrines were normal, and neck ultrasound did not reveal any parathyroid lesions. She underwent parathyroidectomy three weeks later after a period of intravenous hydration. A 2 cm left superior parathyroid adenoma was excised, and the plasma calcium level promptly normalised. Genetic testing for familial hyperparathyroidism revealed an autosomal dominant heterozygous CDC73 variant, which is associated with Hyperparathyroidism-Jaw Tumour syndrome. The Clinical Genetics team is arranging genetic testing for her first-degree relatives. She delivered a live baby at 38 + 6 weeks of gestation via emergency caesarean section, performed for foetal hypoxia on cardiotocography, and genetic testing of the newborn child using umbilical cord blood was performed at the time of delivery. She will undergo regular screening for uterine, renal and jaw tumours (every 5 years), and is planned for 6-monthly calcium and parathyroid hormone tests. Conclusion Primary hyperparathyroidism is best treated with parathyroidectomy before pregnancy as the maternal and foetal complications increase according to the hypercalcaemia severity. During pregnancy, mild cases could be treated conservatively while parathyroidectomy is reserved for severe cases and is performed in the second trimester. Germline CDC73 analysis is recommended in young pHPT patients, and in this case revealed a pathological variant associated with Hyperparathyroidism-Jaw Tumour syndrome, familial isolated pHPT and parathyroid carcinoma.

Suitability of Crushed Sandcrete Block (CSB) as a Partial Replacement for Fine Aggregate in Concrete Structures

In concrete structures, debris generated from construction, renovation, and demolition of buildings is often referred to as construction and demolition waste. These waste materials may be very important to recycle for several reasons for instance, recycling materials such as glass, metal, concrete, and wood waste can lessen our reliance on virgin resources, preserve natural resources, and lessen the negative environmental effects of resource exploitation. The suitability of crushed sandcrete block (CSB) for use as a partial replacement for fine aggregate in concrete was examined. The physical and mechanical properties of the crushed sandcrete block and river sand were determined and compared. The specific gravity of the crushed sandcrete block was found to be 2.58 while that for river sand was 2.66. The concrete with compressive strength of 25N/mm2 at 28 days’ hydration period was calculated for the normal mixture as the control. The percentage mix of the fine aggregate was substituted with CSB in different mix proportions of 0:1(0%), 1:3(25%), 1:2(33.3%), 1:1(50%), 2:1(66.7%), 3:1(75%) and 1:0(100%) of crushed sandcrete block and river sand by weight as fine aggregate. The concrete cubes were cured, and compressive strength tests were carried out at 7, 14, and 28 days. It was observed that the 28-day density and compressive strength for concrete cubes with crushed sandcrete block alone as fine aggregate (i.e. 100%) were found to be 2420kg/m³ and 22N/mm² respectively compared to the 0:1(0%) proportion which was found to be 2485kg/m³ and 26N/mm² respectively. It was observed that the density and compressive strength reduced with the increasing addition of CSB in all the proportions.

Comparison of the adhesion of adhesive pastes on removable dental prostheses from different commercial companies

The use of conventional removable dental prostheses shows the lack of retention and stability, so the use of adhesives for prostheses has been generalized to improve their resistance to detachment. The adhesion of adhesive pastes in removable dental prostheses of different commercial companies was compared. The empirical component involved an in vitro experiment using two adhesive pastes: Corega and Denta Firme, applied on acrylic discs that were previously hydrated and then placed on glass slabs to measure the adhesion strength. This process involved the uniform application of 5 ml of each paste on the discs, followed by a hydration period of 8 minutes. Adhesion strength was measured using a digital scale, recording the highest value obtained during vertical debonding of the disc from the tile. This study revealed that the differences in the bond strength of the adhesive pastes evaluated for dentures are minimal. Denta Firme demonstrated the highest bond strength in the short term. It is concluded that the study failed to determine the durability of the bond strength of the pastes over time. However, the findings indicate that the use of adhesives significantly improves the retention of conventional removable or total dentures. Consequently, it is recommended that dental professionals carefully choose the most appropriate adhesive for each patient, considering individual characteristics and specific needs, in order to take full advantage of the benefits offered by these products