Evaluation Of Mechanical Properties Of Palm Oil Fuel Ash (pofa) Blended – Granite - Gravel Concrete

2.6 Permeability of Concrete with Replaced POFA
      According to Chindaprasirt et al. (2007), the permeability of the concrete was higher than the POFA-cement concrete. The POFA content also influences the permeability of the concrete. As studied by the mentioned author, the permeability of the concrete was reduced when the replacement level of the POFA was elevated. The permeability values of the concrete with 20 % of POFA content to 40 % of content were 0.59 x 10 -12 m/s and 0.41 x 10-12 m/s respectively. However, when the replacement level was increased to 55 %, the permeability of the POFA concrete was increased to 3.30 x 10 -12 m/s. This shows that the POFA content in replacing the cement requires careful thinking as a promising result of mortar needs to be collected. Meanwhile, the result of the permeability test with a different replacement ratio of POFA shown by Tangchirapat et al. (2009) pictured that the permeability of the specimen decreased when the POFA replacement percentage rose from 10 % to 20 % but an increased permeability was shown as the replacement percentage reached 30 %. Hossain, (2016) performed the permeability test with the high replacement level of POFA which is from 55 % to 70 %. Eventually, an increment permeability of the specimen resulted. Therefore, it can be said that the higher replacement ratio of the POFA content will contribute to the reducing of permeability but as the limit is reached, the additional of the POFA content will cause the result to be opposed to the initial trend. The Figure 2.8 shows the general trend of the permeability as the replacement ratio increases.