Effect of External Sulfate Attack on Self Compacted Concrete

Self-compacting concrete (SCC) is an innovative concrete that does not require vibration for placing and compaction. It is able to flow under its own weight, completely filling formwork and achieving full compaction, even in the presence of congested reinforcement. The effect of external sulfate attack was studied-Es (very sever exposure SO4>10000ppm) according to ACI 318-11. The mix design method of SCC used is according to EFNARC 2002, and then must satisfy the criteria of filling ability, passing ability and segregation resistance. The experimental program focuses to study two different chemical composition of sulfate resistance Portland cement with different percentage of silica fume replacement by weight of cement and W/cm (0.3 and 0.35). The SCC mixes with cement type 1(C3S= 46.39 and C3S/C2S = 1.78) shows more resistance to Es than mixes with cement type 2 (C3S= 61.22 and C3S/C2S =4.44). The SCC mixes containing 10% SF as replacement of cement shows more resistance to external sulfate attack. The percentage of increase is 17.95% for SCC mixes with type 1 cement and W/cm =0.3 and 17.88% for SCC mixes with type 2 cement and W/cm =0.3 compared to reference concrete mixe

Statistical Models for Predicting the Optimum Gypsum Content in Cement Mortar

One of the most important problems in concrete industry in Iraq is deterioration due to internal sulfate attack that causes damage of concrete and hence reduces its compressive strength, increases its expansion and may be lead to its cracking and destruction. Linear regression analysis is used to predict the optimum SO3 content (O.G.C) on the basis of cement chemical composition, Blaine fineness and age. Three models are presented, the first one is an early age model (less than or equal to 7- days). Then a late age (greater than 7-days) model was developed based on the predicted optimum SO3 content of early age and late age. The third model was an all ages model and it is a general model specially for OPC. The important results obtained are the positive effect of C3S, C3A and C4AF on optimum SO3 content in cement mortar. The effect of C3A on optimum SO3 content is about twice that of C4AF. The study also showed a trend of positive and important effect of the fineness of cement

Some Mechanical Properties of Concrete by using Manufactured Blended Cement with Grinded Local Rocks

he use of blended cement in concrete provides economic, energy savings, and ecological benefits, and also provides. Improvement in the properties of materials incorporating blended cements. The major aim of this investigation is to develop blended cement technology using grinded local rocks . The research includes information on constituent materials, manufacturing processes and performance characteristics of blended cements made with replacement (10 and 20) % of grinded local rocks (limestone, quartzite and porcelinite) from cement. The main conclusion of this study was that all types of manufactured blended cement conformed to the specification according to ASTM C595-12 (chemical and physical requirements). The percentage of the compressive strength for blended cement with 10% replacement are (20, 11 and 5) % , (2 , 12 and, 13) % and (18, 15 and 16) % for limestone , quartzite and porcelinite respectively at (7,28 and 90)days for each compare to the reference mix, while blended cement with 20% replacement are (-3, -5 and -11) ,(6, -4% and -5) and (6, 4 and 6) % for limestone , quartzite and porcelinite respectively at (7, 28 and 90)days compare to the reference mix .The other mechanical properties (flexural tensile strength and splitting tensile strength) are the same phenomena of increase and decrease in compressive strength. The results indicated that the manufacture Portland-limestone cement, Portland-quartzite cement and Portland-porcelinite cement with 10% replacement of cement with improvable mechanical properties while the manufacture Portland-porcelinite cement with 20% replacement of cement with slight improvable mechanical properties and more economical cost

Application of Central Composite Design to evaluate the antilisterial activity of hydro-alcohol berry extract of Myrtus communis L.

Abstract The antimicrobial activity of the hydro-alcohol extract of Myrtus communis L. (ME) berries was investigated against six Listeria monocytogenes strains (2 type strains and 4 isolates). Sub-lethal ME concentrations reduced L. monocytogenes counts by at least 2 log cycles. A Central Composite Design was used to investigate the combined effects of sub-lethal concentrations of ME (0.039–0.195 mL/100 mL), NaCl (0–2.0 g/100 mL) and pH (5.0–7.0) on strains growth. ME affected growth parameters, generally extending lag phase length and reducing maximum growth, sometimes with interactive effects with pH. The highest ME concentrations (0.117–0.195 mL/100 mL) combined with the lowest pH values (5.0–6.0) strongly reduced or even inhibited strains growth. Total phenolic content (TPC) and radical scavenging activity were also determined. ME had a TPC of 5315 ± 20 mg/kg of gallic acid equivalent, and malvidin-3- O -glucoside was the most abundant anthocyanin. In vitro radical scavenging activity, determined by TEAC assay, was stable during 70 days of refrigerated storage. In conclusion, low ME concentrations, combined with salt and pH, were effective in reducing or containing cell growth. This antilisterial effect has interesting perspectives on industrial application; ME hydro-solubility can be considered a useful feature when antilisterial strategies are applied in food formulation

Aromatic Plants: use and nutraceutical properties

In the last years it has progressively been observed a substantial increase in the use of aromatic herbs and essential oils. Mediterranean area represents a particular environment in which many constraint factors (high light, temperature, drought, salinity, air pollution, etc.) induce a wide range of secondary metabolites in plants. These compounds can be useful utilized by humans for different applications: antibiotics, antimycotic, animal nutrition, cosmetics, food additives, biorepellents, etc. This paper reviews the literature on recent agro-industrial applications of Mediterranean plant species and medicinal plants used for the treatment of infectious diseases. The review includes accounts of extracts, essential oils and other active principles isolated from plants that have been used by folk medicine as antimicrobial agents. The name and part of the studied plants, spectrum of activity, type of active compounds and methods used are discussed and their mechanisms of action as well