Hydration behaviour of limestone-calcined clay and limestone-slag blends in ternary cement

The effect of kaolinitic calcined clay and slag on the hydration of limestone-containing ternary blended cements was investigated. The effect of alumina from different sources of SCMs was considered to activate the formation of carboaluminates. Ternary blends with 50% ordinary portland cement clinker, 45% blends of limestone calcined clay (LC2) in 1:2 blend and slag limestone blend (SLS) in 2:1 mix proportion with 5% of gypsum were studied. The hydration behaviour was analysed based on cement mortar compressive strength, heat of hydration using an isothermal calorimeter and bound water measured using thermal gravimetric analysis (TGA). In addition, the degree of hydration of clinker phases and the composition of calcium - alumino - silicate - hydrate (C-A-S-H) gels forming in two different systems were compared on 90 days hydrated samples analysed using X-Ray diffractometry (XRD) and scanning electron microscopy - energy dispersive X-ray spectroscopy (SEM-EDX) respectively. The results show a rapid early strength development in limestone calcined clay cement blend (LC3) but a lower clinker hydration in comparison with slag limestone cement blend (SLSC) at later ages. In both the cement blends the formation of hemicarboaluminate (Hc) and monocarboaluminate (Mc) was confirmed at 90 days, but the conversion of Hc to Mc was higher in SLSC. Results further confirmed a lower degree of hydration and higher alumina incorporation in the C-A-S-H gel in the LC3 comparison to SLSC. The presence of calcium hydroxide was also confirmed in the SLSC blend due to the hydraulic nature of slag that supported the later age conversion of Hc to Mc as not seen in LC3.

Perilaku gizi dan hidrasi selama kehamilan berhubungan dengan konstipasi

Background: Prevalence of constipation in pregnant women is estimated at 11-38%. Impact of constipation in pregnant women are haemorrhoids and decreased quality of life. Meanwhile, determinants known to influence constipation during pregnancy are hormonal changes, poor diet, low physical activity and lack of fluid consumption. Objectives: Identify the determining factors that can affect occurrence of constipation and investigated the difference based on constipation status among pregnant women in Public Health Centre in Jakarta, Indonesia;Methods: This research was a cross sectional design conducted in July 2019 to October 2019. The subject was pregnant women. We used accidental sampling method to recruit subjects in Public Health Centre, Kebun Jeruk, West Jakarta. We measured the determining factors of constipation among pregnant women. Characteristic of pregnant women, knowledge, attitudes and practices were measured by questionnaires. Anthropometrics data for weight, height, and mid arm circumference were measured. Haemoglobin level was also measured. Bivariate analysis using Pearson or Spearman was used to investigate which factors associated significantly with constipation among pregnant women. We also assessed the difference of characteristic of pregnant women, knowledge, attitudes and practices using differential analysis (Mann-Whitney U-test). Results: The results showed that prevalence of constipation was 30%. Differential analysis showed that mothers who experienced constipation had a younger age and low nutritional and hydration behaviour scores. Other variables such as gestational age, weight before pregnancy, upper arm circumference, height, haemoglobin, knowledge score and nutritional attitude and hydration did not show significant differences based on constipation status. Correlation analysis showed an inverse relationship between maternal age and incidence of constipation, with r = 0.242 and a p-value = 0.015. Maternal age, nutritional behaviour and hydration also showed significant inverse relationship with incidence of constipation (r = -0.206 and p-value 0.039);Conclusion: Nutritional and hydration behaviour during pregnancy was related to the occurrence of constipation. Mothers are advised to have good nutrition and hydration behaviour to prevent constipation.

Hydration of Na-saturated synthetic stevensite, a peculiar trioctahedral smectite

Smectite interlayer water plays a key role in the mobility of elements and molecules and affects a variety of geological processes. In trioctahedral smectites, in contrast to saponite and hectorite, the layer charge of which originates from isomorphic substitutions, the stevensite layer charge originates from the presence of octahedral vacancies. Despite its common occurrence in lacustrine environments, stevensite hydration has received little attention compared to saponite and hectorite. Early reports mention a specific hydration behaviour, however, with the systematic presence of a low-angle reflection attributed to the regular interstratification of various hydration states. The present study aims to revisit this specific hydration behaviour in more depth. Within this scope, the hydration behaviour of the three smectite varieties above are compared using synthetic trioctahedral smectites of similar layer charge and various compositions of their octahedral sheets. The chemical composition of the octahedral sheet does not appear to influence significantly smectite hydration for saponite and hectorite. Compared to its saponite and hectorite equivalents, H2O content in stevensite is lower by ~2.0 mmol H2O per g of dry clay. Consistent with this lower H2O content, Zn-stevensite lacks a stable monohydrated state, with dehydrated layers prevailing from 60% to 0% relative humidity. The presence of the regular interstratification of 0W and 1W layers is responsible for the low-angle reflection commonly observed for stevensite under air-dried conditions. Finally, the stevensite identification method based on X-ray diffraction of heated and ethylene glycol-solvated samples is challenged by the possible influence of the octahedral sheet chemical composition (Zn or Mg in the present study) on hectorite swelling behaviour in synthetic Zn-smectites. The origin of this effect remains undetermined and further work is needed to propose a more general identification method.