A Comparative Study on the Compressive Strength of Concrete Using Rice Husk Ash and Waste Paper as Partial Replacement for Fine Aggregates

Abstract

Waste materials has been used in different occasions to develop a sustainable concrete that is more economical and eco-friendlier. Particularly in the Philippines, rice husk ash is in abundance due to rice being one of the major produce of the country. Paper waste is also in question with it being one of the highest components of global waste. With these considered, the researchers evaluated and created a comparison on the compressive strength of concrete mixed with rice husk ash (RHA) and wastepaper to standard concrete. The researchers replaced 5% of the usual aggregates with these said waste materials. The other materials used for this study are Portland Cement Type 1, sand, gravel, RHA, old newspaper as the wastepaper, and water. Following a ratio of 1:2:3, the concrete mixture of both the experimental and the controlled samples were molded into cylindrical PVC molds measuring 152x302mm creating 18 samples; 9 samples for the experimental concrete mixture and 9 samples for the controlled concrete mixture. These samples were tested on the 7, 14, and 21 curing age marks, with 3 samples of each category being tested for each age mark.  The statistical treatment of ‘t-Test for two independent means was applied on the results gathered through the Universal Testing Machine (UTM) with the significance level of 95% or 0.05 as recommended by ASTM International, specifically ASTM C39/C39M. The mean of the individual results was taken and compared. With the results of this study, the null hypothesis is rejected for the 7, 14, and 21 day marks due to having a weaker compressive strength – which is 8.58 MPa out of 22.50 MPa for the 14 day mark and 10.02 MPa out of 24.75 to 25 MPa for the 21 day mark – than the standard controlled concrete.