Durability UHPC structures in wind mills and marine

Durability of the concrete mainly based on hydration of the cementitious material. The structures exhibits to aggressive environmental conditions,eventually affects the load carrying capacity of the  concrete structure,durability is a pivotal issue in civil engineering for the safety and serviceability of the structures.The ultra High performance Fiber Reinforced Concrete (UHPFRC) is a combination of ultra high strength concrete,addition of steel fibers, super plasticized materials are closely compacted to frame densely.most required in construction industry advanced with ultra technology,  The cement based concrete material with densifyed ingredients on the particle packing theory. The requirement of very high compressive strength concrete is the prime design concept across the global construction sector, it reduces the material consumption 40% less than the conventional concrete to enhance the material and accelerate the hydration reaction of the cement, micro silica properties,The UHPFRC materials are cured under steam curing or at elevated temperature,the uhpfrc is a high potentinal  sustainanble material.

The resistance  capacity of concretes structures against  aggressive agents is governed by the nature and  environment.  The deterioration  of concrete occur due to  permeability, water absorption,carbonation and chloride attack,  and the decrease in the water/cementitious ratio. The addition of ultrafine particles  and steel fibers contribute to improve the life of the concrete. The durability of fiber reinforced concrete studied by various researchers 1 Kono K,,etal.tested samples of  sakata mirai foot bridge in japan  exposed to severe environment conditions effected by chlorides.The penetration depth  findings is less than 1mm serving in better way2,3 Charron J.P.Denarié E,Brühwiler E.

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presented the cracks development is greatly impacts on permeability,the cracks show poor resistance against chloride penetration and carbonation  the effect is much lower than normal concrete.4Thomas M,etal.observed long term test results of   UHPC beams exposure to marine and tests conducted for chloride penetration after 13 years found only 7mm  depth and serving in goodness.

5 Corvez D and Masson B exposed UHPC structures in wind mills and marine area shown a great resistance against chemical agents. 6C.D.Atis and O. Karahan reported that concrete specimen with steel fibers have slightly better freeze-thaw resistance when compared plain concrete 7. D.

Niu etal investigated steel fiber volume fraction  have huge effect on  the frost-resisting capacity of steel fiber reinforced concrete of 1.5% volume.and the concrete’s frost-resisting property significantly decreased with 2% volume.8 GU ChunPing et.al.

summarized the information pertaining to the development, composition,microstructural, characterstics  and durability of UHPC9 P. Spiesz. reported the  permeability of water takes in both micro and macro level porosities for normal concrete the permeable porosity accounts to 15%.10,11R.Yu.P.Spiesz.

H.J.H.

Brouwers evaluated the permeable porosity of UHPC is 10% with low binder contents due to particle packing density  and the silica fume mix further much densifies cement matrix.12Koniorczyk etal.proposed the UHPC resistance  against  frost, salt, wettability, and absorptivity is extremely important  in  performance consideration of its durability. The steel fiber reinforced concrete is affected by resistivity of frost by its porosity13Schmidt and Fehling et al. studied the water permeability coefficient parameter of UHPC was reported to be about 0.

0005, which is very low compared to that of the NSC around 0.001514 T. E. T.Buttignol etal revealed the UHPFRC mix creation in a dense and micro structural interconnection with high  level homogeneity and lower capillary porosity lesser 1.

5% resulting a better performance of concrete and higher durability15,16,17 Toutlemonde F.and Resplendino J.showed the very low permeability structure of UHPFRC protects against aggressive  chemical agents such as chloride ions causing corrosivity of steel bars and sulfate attack, leading to concrete structural expansion, and  bonding loss between the cement paste and the aggregates18 S.Abbas et.

al.revealed the  percentage of steel fiber and curing method are the prime important to control mechanical and durability properties.of a phenomenological model 19 Heinz and Ludwig observed the decreasement in pore size of average is less than 5nm(2X107) and the percentage of pore volume ranges  between 1 to 2% of total volume 20 Herold, G., & Muller, H. Studied the addition of steel fibers changes the failure shape of UHPC specimens from complete damage stage or sudden explosion stage shows to ductile21Sanchez-Silva and Rosowsky pointed out  the loss of structural resistance of the member caused due to loss of chloride ingress, leading to steel corrosion  and concrete cracking 22l.

Fehling, E.; Schmidt, M.; and Stuerwald, S., eds. studied the UHPC  water absorption capacity very low, which is approximately 10 and 60 times lesser than that of HPC and NSC, respectively23 Aitcin  described the chloride ion permeability of the order less than 1000 C for HPC and lower than 5000-6000 C is for ordinary concrete. As water/binder (w/b) ratio decreases the connectivity of the pore system 24 Santosh M Muranal and Khadiranaikar R recognized corrosion rate, chloride ion penetration and loss in mass and strength due to acidic environment is lower than that of high performance concrete,          It is evident  from the above literature review many research works on  durability of UHPC focused.

So far, there is no report on  the durability properties of UHPFRC. In this research work the experimental program is carried out to investigate durability properties of UHPFRC by performing the tests of water absorption, Sorptivity, temperature, chloride, Accelerated curing  and Biodeterioration using special  densified materials, water  and binder ratio(w/b=0.22) used to increase compactness density, and toughness, The laboratory observations, which reveals the addition  of Hooked end steel fibers acts as  coupling between granular packing and durability behavior of concrete accounted for the improvement in strength at elevated temperature 90OC helps in gaining durability resistance capacity of the concrete material  suitable for all weather conditions. 

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