Permeability of high strength concrete: Fid-Bau Portal

Permeability of high strength concrete

Gupta, S.M. / Aggarwal, P. / Aggarwal, Y. / Sehgal, V.K. / Siddique, R. / Kaushik, S.K.

Permeability of concrete is of particular significance in structures which are intended to retain water or which come in contact with water. Permeability is intimately related to durability of concrete and it influences the resistance of concrete to sulphate and alkali attack, rate of corrosion of reinforcement, fire and frost. In this paper, permeability of High Strength Concrete is presented. In the High Strength Concrete the water cement ratio is reduced to great extent, therefore the concrete becomes denser in comparison of Normal Strength Concrete. Thus due to increased denseness of high strength concrete, the permeability of concrete is reduced to great extent. The High Strength Concrete is made with concrete mix 1:0.8:2,2 with water-cement ratio as 0.30. The desired degree of workability of concrete at this low water cement ratio is obtained by adding superplasticizer dose at the rate of 2% by weight of cement. In the present investigation the permeability of concrete with 53 grade cement, 12.5 mm size granite as coarse aggregate and Yamuna and Badarpur sand as fine aggregate is studied at 28 days and 180 days. Further the results of permeability of high strength concrete are compared with the normal strength concrete. The permeability of High Strength Concrete without fly ash and silica fume and with partial replacement of cement by equal amount of flyash; silica fume and flyash and silica fume in varying percentage is studied. Test results indicate that with the replacement of cement by equal amount of flyash, silica fume and flyash and silica fume both in varying percentage (as indicated above) in concrete reduces the coefficient of permeability of concrete by 8% to 12% and 25% to 50% respectively at 28 days and 180 days. Further, the coefficient of permeability of concrete with flyash is 15% to 20% less than the coefficient of permeability of concrete with replacement of cement by equal amount of silica fume. The type of the fine aggregate also reduces the coefficient of permeability of concrete. From the test results of above investigation, it can be concluded that the coefficient of permeability high strength concrete with Badarpur Sand as fine aggregate is 8% to 10% less than the coefficient of permeability high strength concrete withYamuna Sand as fine aggregate, the coarse aggregate being same as sand stone of 12.5 mm size. Thus from the results of above investigation, it can be concluded that the coefficient permeability of High Strength Concrete with flyash, silica fume and granite, Badarpur and Yamuna sand as aggregate reduces the coefficient of permeability to the great extend.