Influence of Lime and Coal Bottom Ash as Partial Cement Replacement Material on Mechanical Properties of Concrete

Coal bottom ash (CBA) is waste material like coarse sand collected at the bottom of the furnace during the power generation at the coal operated power plants. However, its huge production becomes a major issue that will bring a negative impact on the environment as it will lead to a higher risk of groundwater contamination. In this study, 10% of CBA with proportions of 5%, 10%, and 15% of lime were used to replace the cement by weight, respectively. A slump test was conducted to measure the workability property. The compressive strength test, split tensile strength test and flexural strength test was carried out after 7 days and 28 days of the curing. Based on the results, the workability of concrete showed a reduction when the cement replacement level increased. The compressive, splitting tensile, and flexural strengths were reduced when cement replacement level increase but the strength was increased with the increase in curing age. However, the concrete containing 10% CBA showed higher split tensile strength than the control

Influence of Partial Replacement of Cement and Sand with Coal Bottom Ash on Concrete Properties

An experimental study was accomplished to study the effect of replacement of both cement and sand with coal bottom ash (CBA) on the properties of the concrete. Control mix was prepared without coal bottom ash replacement and nominated as series A. The mixes of series B were prepared with20 % replacement of cement with 30 hours ground coal bottom ash (GCBA). Mixes of series C were prepared with four percentages (5,10,15,20) of CBA as partial replacement of sand. Mixes of Series D mixes were prepared as a combination of series B and C. Slump flow, compressive strength, and water permeability properties were investigated. Series D mixes showed lower workability compared to the series C mixes and control mix. Compressive strength of series D mix gained slightly higher strength compared to the control mix but lower than series C strength. Series C mixes absorbed more water compared to control mix concrete. Series D mixes achieved lower water permeability coefficient compare to series C which showed lower water permeability than the control

The development and validation of a scoring tool to predict the operative duration of elective laparoscopic cholecystectomy

Background: The ability to accurately predict operative duration has the potential to optimise theatre efficiency and utilisation, thus reducing costs and increasing staff and patient satisfaction. With laparoscopic cholecystectomy being one of the most commonly performed procedures worldwide, a tool to predict operative duration could be extremely beneficial to healthcare organisations. Methods: Data collected from the CholeS study on patients undergoing cholecystectomy in UK and Irish hospitals between 04/2014 and 05/2014 were used to study operative duration. A multivariable binary logistic regression model was produced in order to identify significant independent predictors of long (> 90 min) operations. The resulting model was converted to a risk score, which was subsequently validated on second cohort of patients using ROC curves. Results: After exclusions, data were available for 7227 patients in the derivation (CholeS) cohort. The median operative duration was 60 min (interquartile range 45–85), with 17.7% of operations lasting longer than 90 min. Ten factors were found to be significant independent predictors of operative durations > 90 min, including ASA, age, previous surgical admissions, BMI, gallbladder wall thickness and CBD diameter. A risk score was then produced from these factors, and applied to a cohort of 2405 patients from a tertiary centre for external validation. This returned an area under the ROC curve of 0.708 (SE = 0.013, p  90 min increasing more than eightfold from 5.1 to 41.8% in the extremes of the score. Conclusion: The scoring tool produced in this study was found to be significantly predictive of long operative durations on validation in an external cohort. As such, the tool may have the potential to enable organisations to better organise theatre lists and deliver greater efficiencies in care

Shear performance of strengthened timber beam with intermittent GFRP strips

In this study, the timber beam was strengthened at the shear span with intermitted glass fiber reinforcement polymer (GFRP). The effect of different numbers of GFRP strips, different orientation angles of GFRP strips to the principal axis of the beam, and different warping schemes of GFRP strips on the performance of the timber beam under flexural load was investigated. The experimental shear capacity was validated using an analytical analysis. In the results, the optimum number of GFRP strips was five. The inclined stripping and fully wrapping scheme were achieved higher strengths than vertical stripping and partial schemes, respectively

Material Characterization and Optimum Usage of Coal Bottom Ash (CBA) as Sand Replacement against Concrete Properties

Generally known that the main constituent of concrete mixture is sand, coarse aggregates, cement and water. Presently, the deficiency of natural sand which is one of the raw materials turn into thoughtful issues in construction industry. To resolve the issue of natural sand depletion, industrial waste by-product should be utilized as an alternative material in concrete production. One of the industrial by-product that has an ability to be a replacement of sand in concrete is Coal bottom ash (CBA) which produced by coal based power plants. Therefore, this study aims to define the potentiality of CBA as sand replacement material in concrete. Initially, physical, chemical, microstructural properties like specific gravity, density, sieve analysis, X- ray fluorescence and scanning electron microscopic were investigated. Next, the optimum replacement of sand with CBA was determined based on the workability, compressive and splitting tensile test. The results showed that the CBA and sand have similarity in terms of physical properties. Whereas, according to chemical properties, CBA was classified as Class-F ash. It was found that 10% of CBA as sand replacement material gives the adequate strength and achieved the targeted/designed strength. It was concluded that CBA has good potential to be utilize as sand replacement material

Characterization of mortar with pennisetum purpureum ashes as cement replacement material

In this study, the properties of mortar such as standard consistency, setting time, compressive strength, and water absorption rate were investigated. The cement was replaced with Pennisetum purpureum ashes (PPA) in different particle sizes and dosages. PPA was produced in greyish-white ash with total reactive oxides ranging from 37% to 41.1%. Pennisetum purpureum grass (PPG) was burned with a controlled process at 350 °C for the first 3 hours and 600 °C for another 3 hours at a heating rate of 10 °C/min. Then, PPG was ground in three different grinding durations (1, 3, and 6 hours) producing ashes with particle sizes of 10.58 µm, 10.25 µm, and 9.30 µm, respectively. The physical, chemical, and microstructural properties of PPA were evaluated through several tests; particle size analysis, X-ray diffraction analysis, loss on ignition, and chemical composition. Results indicated that PPA is more suitable for use as filling material as a substitute for cement than pozzolanic material as its reactive oxides are less than 50%. The 15% 6H-PPA at 28 days was found to be the optimum PPA replacement dosage and grinding time with cement as it achieved the highest strength and lower water absorption rate among all samples at 7 and 28 days