Corrosion- induced damage in reinforced concrete structure such as bridges, parking garages, and buildings, and the related cost for maintaining them in a serviceable condition, is a source of major concern for the owners of these structures.
Fly ash produced from south Baghdad power plant with different concentrations (20, 25 and 30) % by weight from the cement ratio were used as a corrosion inhibitor as a weight ratio from the cement content.
The concrete batch ratio under study was (1:1.5:3) cement, sand and gravel respectively which is used in Iraq. All the raw materials used were locally manufactured.
Concrete slabs (250x250x70) mm dimensions were casted, using Poly-wood molds. Two steel bars were embedded in the central position of each slab at the mid- height (about 35 mm), with a space of 100 mm between each other.
A 16 concrete slabs were prepared (0, 20, 25 and 30) wt. % of fly ash. The specimens were partially immersed in 3.5 wt. % NaCl solution in order to predict the corrosion.
Half-cell potential test technique was used to estimate the corrosion rate which is occurred in the steel bar due to the migration of chloride ions through the concrete, depending on the ASTM C876-08.
The result shows that the potential values of steel in concrete were shifts to the positive direction with increasing the percentage of fly ash, because the reduction of porosity by the addition of fly ash which fill the pores and inhibit the chloride ions to reach to steel.
The results also show that the further increase of fly ash (30%) the possibility of carbonation is increased which result in reduction its alkalinity, thereby permitting corrosion of embedded steel.
The concentrations of naturally radioactive made occurring and technically enhanced radioisotopes of fly ash samples, collected from Al-Dura thermal power Plant- south of Baghdad, have been investigated using the NaI(Tl) gamma-ray spectroscopy. The average Activity concentrations of the radio elements 238 U, 232Th and 40K in Fly ash samples are measured accurately and found to be 33.860, 32.6 and 644.64Bq/kg respectively. On the whole the radionuclide's concentrations are still below the global average of 50 Bq/kg for 238U and 232Th, but are much higher in 40K, relative to the global average, about 500 Bq/kg. The absorbed gamma doses in air, due to naturally occurring radionuclides in fly ash samples, are measured and found within the ra
... Show MoreIn this study, concentrations of Radon were measured for fifty two samples of Fly Ash taken from five thermal power plants in the middle and south of Iraq [Al-Rashed, Al-Dura, Al-Musaeb, Al-Naserya, Al-Basrah (AlHaretha)].
The radon concentrations in samples measured by registrat alpha-emitting radon (222Rn) by using (CR-39) track detector, The concentrations values were calculated by a comparison with standard samples The results shows that the radon concentrations is between (91.931-30.645 Bq/m3)
Pseudomonas aeruginosa and Klebsiella pneumoniae appears good growth when replicate to culture with heavy crude oil. K. pneumoniae was less ability to biodegrade the heavy crude oil (66.22 wt.%) compare with P. aeruginosa 74 wt.%). Also the emulsion percent were about 64.8 % and 62.5 % for K. pneumoniae and P. aeruginosa, respectively. The results showed that the emulsions produced from both the strains decrease the surface tension of the media from 68.43 Mn/m (for control sample) to 44.50 and 43.30 Mn/m for P. aeruginosa and K. pneumoniae, respectively. The optimum temperature and pH for the hydrocarbons biodegradation were 28 ºC and 7, respectively. The incubation period of 28 days of the isolated increased hydrocarbons biodegradation
... Show MoreIn this study, experimental mortar combinations with 1% micro steel fibers, were examined to create geopolymer mortars. To test the effect of the fibers on the mortar's resistance, the geopolymer mortar was designed with various proportions of more environmentally friendly materials fly ash and slag. The percentage of fly ash by weight was 50, 60, and 70% of the slag. The best results were obtained when a 50:50 ratio of fly ash and slag were mixed with 1% micro steel fibers. The results showed that the mixtures containing fibers performed better in the considered tests (toughness index, ductility index, and resilience index). In the impact resistance test, the mixture contained 50% fly ash by weight of the slag with a temperature of
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Internal curing is a method that has been advised to decrease the primary age cracking, mainly of concrete mixes using low (water to cementitious materials - w/cm) ratios corresponding to the self-compacting concrete-(SCC). This research aims to study the effect of the internal curing using saturated lightweight aggregate- (LWA) on the steel reinforcing corrosion in SCC. In this research, crushed bricks or thermostone were partially replaced by (20%) by the weight of sand and volumetrically measured. The results showed that the steel reinforcement of internally cured concrete showed a slight increase in corrosion up to 300 days of exposure to the saline solution (containing 3.5% NaCl). The ability of using the crushed bricks or thermostone
... Show MoreInternal curing is a method that has been advised to decrease the primary age cracking, mainly of concrete mixes using low (water to cementitious materials - w/cm) ratios corresponding to the self-compacting concrete-(SCC). This research aims to study the effect of the internal curing using saturated lightweight aggregate- (LWA) on the steel reinforcing corrosion in SCC. In this research, crushed bricks or thermostone were partially replaced by (20%) by the weight of sand and volumetrically measured. The results showed that the steel reinforcement of internally cured concrete showed a slight increase in corrosion up to 300 days of exposure to the saline solution (containing 3.5% NaCl). The ability of using the crushed bricks or thermostone
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The effects of the permeation cement grout with fly ash on the sandy soil skeleton were studied in the present work in two phase; first phase the shear strength parameters, and the second phase effect of these grouted materials on volume grouted zone by injection (51) cm³ of slurry in sandy soil placed in steel cylinder model with dimension 15 cm in diameter and 30 cm in height. The soil sample was obtained from Karbala city and it is classified as poorly graded sand (SP) according to USCS. The soil samples were improved by cement grout with three percentages weight of water cement ratio (w:c); (0.1w:0.9c, 0.8w:0.2c, and 0.7w:0.3c), while the soil samples were dehydrated for one day
... Show MoreLow bearing capacity of weak soil under shallow footings represents one of construction problems.
Kaolin with water content converges to liquid limit used to represent the weak soil under shallow
footing prototype. On the other hand, fly ash, which can be defined as undesirable industrial waste
material, was used to improve the bearing capacity of the soft soil considered in this research. The soft
soil was prepared in steel box (36×36×25) cm and shallow square footing prototype (6×6) cm were
used .Group of physical and chemical tests were conducted on kaolin and fly ash. The soft soil was
improved by a bed of compacted fly ash placed under the footing with dimensions equal to that of
footing but with different de
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