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Fulltext Long-Term Strength Development of Fly Ash-Based One-Part Alkali-Activated Binders

Haruna S, Mohammed BS, Wahab MMA, Kankia MU, Amran M, Gora AM

Materials (Basel), 2021 Jul 27;14(15).
PMID: 34361355 DOI: 10.3390/ma14154160

This research aims to study the effect of the dosage of anhydrous sodium metasilicate activator on the long-term properties of fly ash-based one-part alkali-activated binders (OPAAB) cured at ambient conditions. Powdered sodium metasilicate activator was utilized in the range of 8-16% by weight of the fly ash in producing the OPAAB. The properties examined are hardened density, compressive strength, flexural strength, water absorption, efflorescence formation, and microstructural analysis. The experimental result revealed that the binders exhibited excellent long-term strength properties. The compressive strength of the OPAAP is well correlated with its hardened density. The pastes were found to exhibit good soundness characteristics over the long-term. The absorption of water decreases with an increase in the activator dosage from 8-12%, and beyond that, the water absorption relatively remains the same. Field emission scanning electron microscope (FESEM) micrograph revealed uniformly formed solid matrices with the micro-crack present were observed in the samples. The larger pore size promotes the crystallization of the resulting hydrate substances (N, C)-A-S-H gel. The initial dissolution of the OPAAP occurred within the first 30 min. At longer age of curing, mixtures with a higher dosage of powdered activator tend to absorb less water. Strength properties beyond 28 days are considered as the long-term strength.
Fulltext Investigating Optimal Confinement Behaviour of Low-Strength Concrete through Quantitative and Analytical Approaches

Ali M, Abbas S, Salah B, Akhter J, Saleem W, Haruna S, et al.

Materials (Basel), 2021 Aug 19;14(16).
PMID: 34443196 DOI: 10.3390/ma14164675

Reinforced concrete is used worldwide in the construction industry. In past eras, extensive research has been conducted and has clearly shown the performance of stress-strain behaviour and ductility design for high-, standard-, and normal-strength concrete (NSC) in axial compression. Limited research has been conducted on the experimental and analytical investigation of low-strength concrete (LSC) confinement behaviour under axial compression and relative ductility. Meanwhile, analytical equations are not investigated experimentally for the confinement behaviour of LSC by transverse reinforcement. The current study experimentally investigates the concrete confinement behaviour under axial compression and relative ductility of NSC and LSC using volumetric transverse reinforcement (VTR), and comparison with several analytical models such as Mander, Kent, and Park, and Saatcioglu. In this study, a total of 44 reinforced-column specimens at a length of 18 in with a cross-section of 7 in × 7 in were used for uniaxial monotonic loading of NSC and LSC. Three columns of each set were confined with 2 in, 4 in, 6 in, and 8 in c/c lateral ties spacing. The experimental results show that the central concrete stresses are significantly affected by decreasing the spacing between the transverse steel. In the case of the LSC, the core stresses are double the central stress of NSC. However, increasing the VTR, the capacity and the ductility of NSC and LSC increases. Reducing the spacing between the ties from 8 in to 2 in center to center can affect the concrete column's strength by 60% in LSC, but 25% in the NSC. The VTR and the spacing between the ties greatly affected the LSC compared to NSC. It was found that the relative ductility of the confined column samples was almost twice that of the unrestrained column samples. Regarding different models, the Manders model best represents the performance before the ultimate strength, whereas Kent and Park represents post-peak behaviour.
Mechanical and microstructural properties of high calcium fly ash one-part geopolymer cement made with granular activator

Mohammed BS, Haruna S, Wahab MMA, Liew MS, Haruna A

Heliyon, 2019 Sep;5(9):e02255.
PMID: 31687531 DOI: 10.1016/j.heliyon.2019.e02255

In this present experimental study, geopolymer cement is developed using high calcium fly ash and used in the production of one-part alkali-activated binders. At 8-16 percent of the total precursor materials, the HCFA was activated with anhydrous sodium metasilicate powder and cured in ambient condition. Five mixtures of one-part geopolymer paste were intended at a steady w/b proportion. Density, flowability, setting time, compressive strength, splitting tensile strength and molar ratio impact were envisaged. It was observed that the setting time of the designed one-part geopolymer paste decreases with higher activator content. The experimental findings showed that the resistance of one-part geopolymer cement paste increases with comparatively greater activator content. However, raising the granular activator beyond 12 percent by fly ash weight decreases the strength and workability of the established one-part geopolymer cement. The optimum mix by weight of the fly ash was discovered to be 12 percent (i.e. 6 percent Na2O). At 28 days of curing, one-part alkali-activated paste recorded the greatest compressive strength of almost 50 MPa. The density of the one-part geopolymer paste is nearly the same regardless of the mixes. Microstructural assessment by FESEM, FTIR and XRD has shown that the established geopolymer paste includes quartz, pyrrhotite, aluminosilicate sodium and hydrate gels of calcium aluminosilicate. Based on the experimental information acquired, it can be deduced that the strength growth of one-part geopolymer cement is similar to that of Portland cement.
Fulltext Optimization of Cement-Based Mortar Containing Oily Sludge Ash by Response Surface Methodology

Kankia MU, Baloo L, Danlami N, Samahani WN, Mohammed BS, Haruna S, et al.

Materials (Basel), 2021 Oct 22;14(21).
PMID: 34771834 DOI: 10.3390/ma14216308

In the industries of petroleum extraction, a large volume of oily sludge is being generated. This waste is usually considered difficult to dispose of, causing environmental and economic issues. This study presented the novel experimental method of manufacturing mortar used in civil construction by cement and oily sludge ash (OSA). The defined method was described with a logical experimental study conducted to examine a feasible manufacturing method for casting cement-based mortars by partially replacing cement with OSA. Replacement concentrations for OSA ranged from 0 to 20 percent by cement weight, while the water-to-cement (w/c) ratio was varied from 0.4 to 0.8, and the amount of sand was kept constant. The strengths and absorption rate of the mortar were monitored for 28 days. The OSA contains a crystalline structure with packs of angular grains. Because of OSA in the cement-based mortar mixtures and water-to-cement ratios, the mechanical strength was improved significantly. However, the water absorption trend increased linearly. Using variance analysis, the influence of OSA and w/c ratio on the behavior of mortar was acquired. The developed models were significant for all p-value reactions of <5%. Numerical optimization results showed that the best mixture can be obtained by replacing 8.19 percent cement with OSA and 0.52 as a ratio of w/c.
Fulltext Comparative analysis of the nutritional, biochemical and hematological parameters of pregnant women attending the University of Abuja Teaching Hospital, Nigeria

Emeribe AU, Dangana A, Isa HA, Onoja SO, Otu TO, Ibrahim Y, et al.

Biomedicine (Taipei), 2022;12(1):1-13.
PMID: 35836914 DOI: 10.37796/2211-8039.1237

BACKGROUND: Despite the efforts to encourage the intake of nutritional supplements during antenatal periods, there are still many cases of anemia and protein-energy malnutrition during pregnancy. Hence, this study determined the incidence of anemia, protein-energy malnutrition, and associated risk factors among pregnant women in Abuja, Nigeria.
MATERIALS AND METHODS: This hospital-based, case-control study involved randomly selected 176 pregnant and non-pregnant women attending the University of Abuja Teaching Hospital (UATH), Gwagwalada, Nigeria. Hemoglobin and hematocrit measurements were used to determine anemia incidence, while plasma protein, zinc levels and body mass index (BMI) were used to determine energy index status. Complete blood counts were analyzed using 5 parts-automatic hemo-analyzer, while plasma protein and zinc were analyzed using calorimetric method. Anemia and protein-energy malnutrition were defined using the World Health Organization (WHO) cut-off values.
RESULTS: The mean age of participants was 28.75 ± 5.22 years. Out of 176 participants, 7 (4%) were malnourished while 25% of the participants were anemic. Anemia was significantly associated with participants' occupation (p = 0.002), parity (p<0.001) and gestational age (p<0.001). Most hematological indices, plasma globulin, albumin, protein, and zinc levels were significantly different (p<0.001) among non-pregnant and pregnant women of the first, second and third trimesters.
CONCLUSION: The incidence of anemia and malnutrition was high among study participants. There is a need for improved nutritional intervention, increased awareness and strengthening of health systems in the area of maternal health in Nigeria.