Experimental Analysis on Tensile Behavior of Engineered Cementitious Composite (ECC) using Polypropylene Fiber

The high demand of tensile strength in concrete is always a critical issue for engineers, as 10% of the compressive strength is not sufficient to withstand higher loadings. Lesser ductility and strain capacity is another major issue of normal concrete. In the queue of modern researches, this paper is an attempt to study Engineered Cementitious Composite (ECC) from research of Professor Victor Li, the University of Michigan. ECC is an ultra-ductile cementitious composite which is highly crack resistant, with a high tensile strain capacity over that of normal concrete. The composite replaces coarse aggregates and fine aggregates by sand and fly ash respectively. ECC is made up of OPC, sand (passing from 250 µm and retained on 150µm), Fly Ash (Class F) with addition of Polypropylene fiber on different percentages i.e. 0%, 0.25%, 0.5%, 0.75%, 1.0% were studied. Tensile Strength of ECC was measured by casting & testing cylinders of 4”x 8” in Universal Testing Machine (UTM). The experimental results revealed that 111.40% increment in tensile strength was found at 0.5% PP fiber at ECC 1:1:1 and an increment of 74.74% was observed at ECC 1:0.8:1.2 at 1% PP fiber. The study concludes that this composite could substitute the normal concrete where high tension is the ultimate requirement with higher strain capacity

Effect of Rice Husk Ash and Water-Cement Ratio on Strength of Concrete

In present status quo, number of researcher are working on waste materials as potential supplement for any of the constituent of concrete to cope with sustainable development. As, the ingredients which constitute the body and give strength to concrete are natural available limited material and has to deplete one day. Thus, there is desperately need of alternate that may replace the limited natural resources. In this regard, this study focuses the rice husk ash (waste stuff) as partial replacement of cement and its possible impact on strength of concrete. In addition, this research work also this research work is conducted to investigate the effect of water-cement ratio on the strength of concrete at 10% partially replacement of Rice husk ash (RHA) by the weight of cement. RHA is a mineral admixture obtained by burning husk at certain temperature. Since as per pervious researches, the physical and chemical properties of RHA are very reactive Pozzolans and possess binding properties so can be used as cement supplement. Therefore, for laboratory experimental work, total 144 cubical and 72 cylindrical. In this research, number of concrete specimens were cast and tested at 1:2:4 mix ratio with various w/c ratios i.e. 0.45, 0.50 and 0.60. Further, at each specified water-cement ratio, two mechanical properties (compressive and splitting tensile strength) were determined in Universal Testing Machine (UTM). These physical properties of concrete were investigated at 7, 14, 28 and 56 days curing period. The experimental results show that the compressive strength gets increased up to 14.51% and tensile splitting test strength increased up to 10.71% at the w/c ratio of 0.45. The workability of plain fresh concrete at all w/c ratios is slightly greater than the workability of concrete blended with 10% RHA. Thus, RHA improves the properties of concrete when used in specific amount. As a result, it can reduce the overall cost of construction and it will reduce the adverse environmental effect.

Functional properties of Okra Abelmoschus esculentus L. (Moench): traditional claims and scientific evidences

Okra, Abelmoschus esculentus L. (Moench) is an important vegetable crop cultivated in tropical, subtropical and warm temperate regions around the world. Besides the nutritional benefit, the different parts of the plant are used extensively in traditional medicine (antidiabetic, antipyretic, diuretic, antispasmodic, etc) around the world. This review critically assesses the nutritional values, phytochemistry, preclinical pharmacological properties and the possible future application of the okra. Effort is made to correlate the traditional claims in the context of experimental evidences

Drying Shrinkage Performance of Slabs-on-Grade Reinforced with Recycled Tyre Steel Fibres

Fibre reinforced concrete (FRC) is extensively used in slabs-on-grade (SoG) for ease and speed of construction. Manufactured steel fibres (MSF) are typically used in conventional concrete mixes to eliminate the use of discrete reinforcement and control shrinkage and structural cracks. Owing to their excellent environmental credentials and mechanical properties, recycled steel fibres from tyres (RTSF) can be blended with MSF to increase the performance and sustainability of floor construction. However, there is a lack of research on the actual performance of RTSF in SoG and their effectiveness in controlling shrinkage cracks. This research investigates the structural properties of concrete made with RTSF. It uses a complementary set of numerical modelling and extensive laboratory testing to examine moisture distribution and differential shrinkage over time. Moisture, temperature and strain in prismatic elements were monitored in the lab for almost a year. Shrinkage results from moisture loss, so accurate modelling of moisture diffusion is essential, as it dominates the drying process in concrete and governs the development of shrinkage strains that affect structural elements' short- and long-term deformation and cracking behaviour. To address this, this study uses readily available quantities (namely w/c ratio and concrete maturity) as primary material modelling parameters to investigate the effects of pore relative humidity and ambient temperature on the diffusivity properties of concrete using inverse numerical analysis. As a result, a diffusion modelling approach that can be used in practical applications is proposed and verified through finite element analyses. The results show that numerical predictions are in good agreement with experimental data. Specifically, the model can capture the effects of the w/c ratio, concrete maturity and thermal conditions on the evolution of the moisture profile within drying reinforced and unreinforced concrete elements. The proposed model is used to quantify the drying shrinkage strains and curvature in the laboratory specimens. Finally, a full-scale SoG is numerically modelled to assess its behaviour in terms of curling stresses, lifting up of free edges, cracking strains and differential shrinkage. The model can be used to determine drying shrinkage strains with a high degree of accuracy, thereby allowing for a more realistic assessment of crack evolution in drying concrete elements and its effects on overall structural performance. This work will lead to the development of improved design models for shrinkage in SoG in a format that can be easily implemented in current design recommendations (e.g. TR 34, Model Code, Eurocode)

Mechanistic Study of Cholesterol Monohydrate Dissolution in Aqueous Micellar Surfactant and Sodium Chenodeoxycholate Solutions.

The purpose of this study was to more broadly examine the influence of electrical factors and factors other than electric charge in the interfacially controlled dissolution of cholesterol monohydrate in a nonionic surfactant micellar solutions. Limited baseline studies were also conducted in sodium chenodeoxycholate (NaCDC) solutions, a simple bile acid and the findings from the two systems were compared. The results may be summarized as follows: (1) In the dissolution rate studies in Renex-690 (a polyoxyethylene nonylphenol ether) the interfacial resistance R was found to be relatively constant over a wide concentration range with and without sodium chloride. This constancy of R supports the micelle collision mechanism since the free solute mechanism would be expected to show a direct proportionality between R and the solubilizer concentration. Moreover, these studies showed that Renex-690 (a neutral micelle) itself may be associated with slow interfacial kinetics. (2) In the dissolution rate studies at constant Renex/benzalkonium chloride (BC) and Renex/sodium dodecyl sulfate (SDS) surfactant ratios, when the counterion contribution from the ionic surfactant is taken into account the R values were found to be essentially superimposable over a range of solubilizer concentration. Similar patterns were observed with long chain alkylamines and the fatty acids at pH conditions where these surfactants exist in their charged forms. (3) At low electrolyte levels, in the case of BC or SDS/Renex-690, the dissolution kinetics data was essentially quantitatively described by the physical model employing the classical Smoluchowski flocculation theory of colloidal particles and the Verwey and Overbeek theory of electrical double layer repulsion and dispersion attraction. When the electrolyte levels are high, however, the kinetics of dissolution become controlled by convective diffusion in the aqueous boundary layer. (4) It was found that uncharged amphipathic compounds were able to enhance the dissolution kinetics beyond the maximum rates found with Renex-690 alone. These results and other results with charged surfactants were examined by considering factors associated with the micellar structure (hydrophilicity/hydrophobicity of the Renex-690 micelle) and possible factors associated with cholesterol crystal surface. (5) Interestingly, striking similarities were found in the results obtained with NaCDC system containing different electrolyte type and concentration and Renex/ionic surfactant systems.Ph.D.Pharmacy sciencesUniversity of Michiganhttp://deepblue.lib.umich.edu/bitstream/2027.42/159001/1/8224959.pd

A Review of Preventive Health Care in Geriatrics through Ayurveda

Ayurveda is basically the science of life and longevity. Ageing is a process of physical, psychological and social change in multi dimensional aspects. According to the Ayurveda, ageing is outcome of kala or parinama. Vata dosha is the most important factor in the pathophysiology of ageing obviously because of its natural predominance at that stage of life. Ayurveda advocates an excellent approach for promotion of health, prevention of diseases and delaying the process of ageing with number of measures mentioned in svastha chatushka and rasayanadhyaya of charakasamhita, time to time panchakarma and various herbal drugs. Jarachikitsa or Rasayana in Ayurveda is a unique therapeutic methodology to delay ageing and to minimize the intensity of problems occuring in this degenerative phase of one's life. Prevention and management of health problems could help the elderly to improve quality of life and remain self dependant for their daily activities to maximum possible extent

Effect of inhibitors on corrosion of aluminium in acidic medium

220-223Corrosion of aluminium in acidic medium (0.1 N HC1) has been studied by Tafel intercept logarithmic polarization and weight loss methods using two inhibitors, namely Triton X-100 and gelatin. Open circuit potential, inhibition efficiency, corrosion current and corrosion rate have been determined in the absence and presence of inhibitors at different concentrations such as 0.1, 0.2, 0.3, 0.4 and 0.6%. It is observed that the inhibition increases with the increase in concentration of the inhibitors in acidic media. The inhibition efficiency of the Triton X-100 is found to be higher than that of gelatin. Thus, Triton X-100 can be considered as a better inhibitor. </span

Coconut shell ash as cementitious material in concrete: a review

In recent years, there has been great concern about introducing new supplementary cementitious materials (SCM) in place of ordinary Portland cement (OPC) in concrete. The aim of this study is to check the behavior of coconut shell ash (CSA) with various proportions in concrete. Coconut shell is available in abundant quantity in local agricultural fields and considered as waste product. On the other hand, cement production emits a lot of toxic gases in the atmosphere which causes environmental pollution and greenhouse gases. Thus, CSA might be utilized as a cementitious material in concrete for sustainable development. This review article provides a detailed overview of the fresh and mechanical properties of various research studies. It is found that by incorporating the 10% of CSA into concrete results in the improvement of mechanical properties of concrete such as compressive, split tensile strength and flexural strength of concrete after every curing day respectively. Moreover, the modulus of elasticity enhanced while using 10% of CSA in concrete and the workability of fresh concrete was declined as the percentage of CSA increases. In addition to that, the use of CSA in concrete can reduce the total carbon foot print while reducing the overall cost of concrete manufacturing