Effect of Coarse Aggregate Sizes and Replacement Levels on the Strength of Palm Kernel Shell (PKS) Concrete

The maximum coarse aggregate size used in concrete can impact on its strength. An investigation of the effect of coarse aggregate size and replacement level of granite with palm kernel shell (PKS) on the compressive and tensile strengths of PKS concrete were investigated. Mix proportion by weight of 1:1½:2 with w/c of 0.50 were used. All samples were tested at 7 and up to 90 days. Results showed that both compressive and splitting tensile strengths increased with increase in aggregate sizes. Both strengths however decreased with increase in replacement levels of granite with PKS. Optimum replacement level of granite with PKS was 25% with compressive and tensile strengths of 22.97 N/mm2 and 1.89 N/mm2 respectively at maximum coarse aggregate size of 20 mm. However, at 50% PKS content, which results in lightweight concrete, compressive strength was 18.13 N/mm2 which is above the minimum value of 17 MPa for lightweight concrete

Influence of Curing Age and Mix Composition on Compressive Strength of Volcanic Ash Blended Cement Laterized Concrete

This study investigates the influence of curing age and mix proportions on the compressive strength of volcanic ash (VA) blended cement laterized concrete. A total of 288 cubes of 100mm dimensions were cast and cured in water for 3, 7, 28, 56, 90 and 120 days of hydration with cement replacement by VA and sand replacement by laterite both ranging from 0 to 30% respectively while a control mix of 28-day target strength of 25N/mm2 (using British Method) was adopted. The results show that the compressive strength of the VA-blended cement laterized concrete increased with the increase in curing age but decreased as the VA and laterite (LAT) contents increased. The optimum replacement level was 20%LAT/20%VA. At this level the compressive strength increased with curing age at a decreasing rate beyond 28 days. The target compressive strength of 25N/mm2 was achieved for this mixture at 90 days of curing. VA content and curing age was noted to have significant effect (α 0.5) on the compressive strength of the VA-blended cement laterized concrete

Effect of Batching Methods on the fresh and hardened properties of Concrete

This paper investigated the effect of batching by mass and volume on concrete’s compressive strength and workability. Influence of mix proportion at five levels and various water-cement ratios were also studied. All samples were cured by complete immersion in water and tested up to 28 days. The results indicated higher workabilities for concrete batched by mass than concrete batched by volume at all w/c ratios and mix proportions investigated. The workability increased with increase in w/c ratios in both methods. The compressive strength results showed that for rich structural mixes (1:1:2 and 1:1.5:3), concrete batched by mass had 20 % and 6 % strength increases respectively over the concrete batched by volume. Ordinary structural mix (1:2:4) had 14 % increase while non-structural mixes (1:3:6 and 1:4:8) had 8 % and 6 % increases respectively. In all cases, concrete batched by mass had better fresh and hardened properties of concrete

An Investigation into the Pozzolanic properties of Dutsin Dushowa volcanic ash of Jos Plateau

This study investigates the pozzolanic properties of the volcanic ash (VA) sample obtained from Dutsin Dushowa, Kerang in Mangu Local Government Area of Plateau State. Chemical Analysis of the VA sample was carried out to determine the oxide contents, so also were some physical properties (specific gravity, fineness, soundness, consistency, and water requirement and setting times (initial and final)) tests carried out on the VA sample and VA-blended cement samples. The result reflects a Silicon Dioxide (SiO2) content of 41.13% and a total Silicon Dioxide, Iron Oxide, and Aluminium Oxide (SiO2+Fe2O3+Al2O3) content of 70.99%. The VA sample has a specific gravity value of 2.65 kg/m3 while the VA-blended cement was noted to be finer than the control (Dangote - Obajana) cement. The soundness of the VA-blended cement ranged between 1.5 and 4.5 for replacement levels of 0% to 30%. The consistency increased from 30.0% to 31.5% as VA substitution increased from 0% to 30%. The water required for a standard consistency was noted to increase as the VA content increased. The initial and final setting times increased from 50 to 105 minutes and 135 to 180 minutes respectively for this replacement levels. All the VA-blended cements thereby satisfy the various code requirements up to the 30% replacement levels

Assessing the Mechanical Performance of Ternary Blended Cement Concrete Incorporating Periwinkle Shell and Bamboo Leaf Ashes

The study investigates the mechanical properties of concrete incorporating Periwinkle Shell Ash (PSA) and Bamboo Leaf Ash (BLA) as cementitious binders. Concrete cube (100mm) prepared from a standardized prescribed mix of 1:2:4, batch by volume was taken as the reference mix. The cement component in the reference mix was replaced with combined % weight of periwinkle shell ash (10-30%) and bamboo leaf ash (10% fixed) given five blended mixes. Water-cement ratio of 0.60 was adopted for the reference and blended mixes. A total of 144 cube specimens were evaluated for compressive and tensile splitting strength at four curing ages up to 56 days. The results indicated that the compressive strength generally increases with curing age, and that the mix containing 80% cement-10%PSA-10%BLA, outperformed that of the reference mix at 28 and 56 days. The tensile splitting strength increase with curing age and decreases as the % weight of PSA increases from 15% to 30%. A higher tensile splitting strength value was attained with mix 2 than the reference mix at 14, 28 and 56 days.  The regression equation for the strengths relationship was obtained as FSP = 0.141 (Fcu) 0.873. The study concluded that mix 2 proportion is adequate for the production of ordinary structural mix concrete. Keywords: periwinkle shell ash, bamboo leaf ash, blended cement concrete, compressive strength, tensile Splitting strengt

Influence of palm ash on properties of light weight self-compacting concrete

The huge amount and non-utilization of oil palm biomass has created a major disposal problem. The use of lightweight concrete improves structural efficiency, as well as constructability for ease of repair and renovation works. Self-compacting concrete (SCC) reduces voids without vibration. This experimental work examined the effect of influence of Palm ash (PA) on lightweight self-compacting concrete (LWSCC). Palm ash was used to replace cement in the production of lightweight self-compacting concrete in order of 10, 20, 30, 40 & 50% respectively; slump flow, T50, V-funnel and L-box test were carried out for the workability and passing ability test on fresh concrete. The control mix was without PA. While Compressive, flexural and split tensile strength tests were carried out on the hardened concrete. The result showed 20% palm ash replacement as the optimum replacement within which the standard strength requirement for hardened concrete remained satisfied. The result of this study can be applicable to effective concrete mixtures suitable for repairing existing structures and element in rural areas

Neural and behavioural changes in male periadolescent mice after prolonged nicotine-MDMA treatment

The interaction between MDMA and Nicotine affects multiple brain centres and neurotransmitter systems (serotonin, dopamine and glutamate) involved in motor coordination and cognition. In this study, we have elucidated the effect of prolonged (10 days) MDMA, Nicotine and a combined Nicotine-MDMA treatment on motor-cognitive neural functions. In addition, we have shown the correlation between the observed behavioural change and neural structural changes induced by these treatments in BALB/c mice.We observed that MDMA (2 mg/Kg body weight; subcutaneous) induced a decline in motor function, while Nicotine (2 mg/Kg body weight; subcutaneous) improved motor function in male periadolescent mice. In combined treatment, Nicotine reduced the motor function decline observed in MDMA treatment, thus no significant change in motor function for the combined treatment versus the control. Nicotine or MDMA treatment reduced memory function and altered hippocampal structure. Similarly, a combined Nicotine-MDMA treatment reduced memory function when compared with the control. Ultimately, the metabolic and structural changes in these neural systems were seen to vary for the various forms of treatment. It is noteworthy to mention that a combined treatment increased the rate of lipid peroxidation in brain tissue

Inhibition of Dopamine Receptor in Neonate Hippocampus: Immunolocalization of Post Synaptic Density Protein-95 and Dopamine Receptor in vivo

The effect of haloperidol on neonatal dopaminergic neurotransmission in the hippocampus of postnatal day 20 rats (P.20) was investigated in this study. Haloperidol blocked dopamine receptors (D2R) and inhibited D2R on the membrane of neonate neurons. For this study the 0.5 ml (20 mg/kg) of haloperidol was administered to pregnant female animals intraperitoneally a week before delivery. At day P.20, 5 control animals and 5 haloperidol treated animals were taken to the behavioral studies room for the Y maze and Novel object recognition test, which was done 7 am in the morning before mating. Electrophysiology was done with 2 control pups and 2 treated pups. Electrodes were implanted in the brain at the hippocampal region 2 mm beneath the bregma, 2 mm lateral to the midline. Anterior Posterior (AP=0), Medial Lateral (ML=2 mm). Also immunolocalization and immunofluorescence of post synaptic density protein (PSD-95), hippocampal morphology and hippocampal neurons have been done respectively. Results from this study showed a decline in memory index for the Y maze as a result of the effect of D2R blockade thereby inhibiting neurotransmission in newborns. Electrophysiology result in this study showed an increase in the root mean square (RMS) of control pups. The increase in RMS is equivalent to increase in wave burst pattern caused by neuronal excitation. Immunochemistry result showed an increase in the number of PSD-95 in the hippocampus of an increase in tyrosine hydroxylase in the hippocampus of the treated neonatal rats when compared to the control neonatal rats Immunofluorescence showed decline in the number of neurons in the haloperidol treated rats and it also caused hippocampal damage in terms of morphology. Furthermore, results from electrophysiology showed a statistical significant difference with P value 0.04229 (P<0.05) using the student t-test. These findings suggest that D2R inhibition may cause decline in memory function, impair learning in newborns and disrupt neonatal dopaminergic neurotransmissio

Women have enhanced bone loss associated with phosphaturia and CD4+ cell restoration during initial antiretroviral therapy

OBJECTIVE: We compared bone mineral density (BMD) changes and their correlates, between men and women participating in two randomized trials of initial [antiretroviral therapy (ART)] regimens, with or without tenofovir disoproxil fumarate (TDF). METHODS: Covariates in linear regression models of 48-week hip and spine %BMD changes, by dual energy X-ray absorptiometry, included baseline and 48-week changes in plasma viral load, CD4 cells, plasma C-terminal telopeptide, procollagen 1 N-terminal propeptide and glomerular filtration rates, and the 48-week area under the curve of fractional excretion of phosphate. RESULTS: Despite overall hip and spine BMD declines of 2.8 and 2.9%, respectively, plasma viral load suppression to less than 50 vs. at least 50 copies/ml was associated 1.0% (P = 0.02) and 0.8% (P = 0.01) less BMD decline. Women had lower baseline spine (P = 0.04; n = 59 women, 418 men) and hip BMD (P = 0.01) in adjusted models, with 1.7% more hip decline on ART than men (P = 0.001). Serum phosphate was positively associated with baseline spine BMD in women (P = 0.03) but not men, and area under the curve of fractional excretion of phosphate was negatively associated with spine BMD changes, particularly in women randomized to TDF regimens (P = 0.03 and 0.054 for interactions by sex, and randomization to TDF vs. non-TDF regimens, respectively; n = 44 women, 326 men). Women also had 0.6% (P = 0.004) more hip BMD decline than men associated with each 100 CD4 cells/μl increase on ART (P = 0.02; n = 49 women, 379 men). CONCLUSION: Women randomized to TDF-containing ART had accentuated spine loss associated with phosphaturia, and accentuated hip loss associated with CD4 restoration, regardless of TDF exposure. Viral load suppression reduced bone loss

High-risk human papilloma virus and cervical abnormalities in HIV-infected women with normal cervical cytology

Background: The prevalence of High-Risk Human papilloma virus (HR-HPV), a necessary cause of invasive cervical cancer (ICC) is relatively high in HIV infected women. Gaps exist in our knowledge of the optimal approaches for managing women who have HR-HPV with normal cervical cytology (NCC) particularly in settings of HIV infection. Methods: Between May 2012 and June 2013 we conducted a colposcopic assessment of HIV-infected women with prior (NCC) and known HR-HPV status to compare cervical abnormalities in women with and without HR-HPV. Colposcopic examinations were done at the Operation Stop Cervical Cancer (OSCC) unit of the Jos University Teaching Hospital (JUTH), Jos, Nigeria. Abnormal colposcopic finding (ACF) was defined as areas of aceto-white epithelium involving the squamo-coulumnar junction, areas of punctation, mosaic pattern or atypical vessels. We compared proportions of ACF as well as histologic grades of cervical intra-epithelial neoplasia (CIN) in women with or without HR-HPV. Statistical analysis was done on STATA. Results: We conducted colposcopic examinations in 78 out of 89 (86.5%) eligible women. The mean age of the cohort was 32.4 years (SD ±4.6) with a median 32 years (IQR 29–36). After a mean follow up time of 20.1 months from the initial cervical pap cytology and HR-HPV testing, we found 12 of 78 (15.4%) women with ACF. The odds for an ACF was statistically higher [OR = 4.0 (95% CI: 1.1-14.7)] in women with HR-HPV compared to those without. Of the twelve women with ACF, subsequent histologic examination of colposcopically directed cervical biopsies confirmed CIN 1 in 4 cases (33.3%), CIN 2 in 1 case (8.3%), CIN 3 in 2 cases (16.7%), carcinoma-in-situ (CIS) in 2 cases (16.7%), and normal cervix in 3 (25.0%). Overall, the proportion of women detected with any grade of CIN was 11.5% (9/78) and 6.4% (5/78) were CIN 2 or greater lesion (CIN2+). Conclusion: HIV-infected women with NCC and HR-HPV had a four-fold higher likelihood for an ACF. The practice of early colposcopic examination of HIV-infected women with prior NCC and HR-HPV may increase early detection of higher grade CIN and CIS cancer stages in our setting