Rice Husk Ash
SUPPLEMENTARY USE OF RHA
RHA has been used as a good pozzolanic and supplementary material in concrete as investigated in different literatures. Besides that, it participates to produce denser and durable concrete with a particular level (about 20-30%) of replacement. There are various advantages of RHA - improved strength, reduced material costs due to cement saving, durability properties, environmental benefits to the disposal of RHA waste - have been observed to use in cement or concrete.
ADVANTAGES OF SUPPLEMENTARY USE OF RHA
Improves compressive strength (Saraswathy and Song, 2007; Givi et al., 2010; Safiuddin et al., 2010), flexural strengths (Ismail and Waliuddin, 1996; Zhang et al., 1996; Coutinho, 2003) and split tensile strength (Sakr, 2006; De Sensale, 2006; Habeeb and Fayyadh, 2009).
RHA mixed concrete shows better bond strength as compared to OPC concrete (Sakr, 2006; Saraswathy and Song, 2007).
Permeability of concrete decreases (Zhang et al., 1996; Rodrigues et al., 2006; Saraswathy and Song, 2007), chloride diffusion and chloride permeation reduces (Nehdi et al., 2003; Ganesan et al., 2008).
RHA makes a role to increased resistance to chemical attack (Chindaprasirt et al., 2007).
Shows better durability of concrete (Coutinho, 2003; Bakar et al., 2012).
Improves resistance to sulfate attack (Sakr, 2006; Chindaprasirt et al., 2007; Chatveera and Lertwattanaruk, 2009).
Reduces the amount of cement for making concrete up to 20% by weight (Givi et al., 2010).
Improves the corrosion resistance and strength of concrete as compared to that of OPC concrete (Saraswathy and Song, 2007; Chindaprasirt and Rukzon, 2008; Bakar et al., 2012).
Reduces shrinkage due to particle packing, making concrete denser (Habeeb and Fayyadh, 2009).
Enhances workability of concrete (Coutinho, 2003; Habeeb and Fayyadh, 2009).
Reduces heat grow through the walls of buildings (Lertsatitthanakorn et al., 2009).
Reduces amount of super plasticizer (Sata et al., 2007).
Decreases air permeability due to the filler and pozzolanic effect (De Sensale, 2006).
Electrical resistivity (Gastaldini et al., 2009) and ultrasonic pulse velocity OPC concrete. For about 20-30% of concrete increase (Safiuddin et al., 2010).
Compressive strength is directly related to the concrete porosity, RHA reduces porosity of RHA in the production of cement or concrete that can be concrete (Zhang et al., 1996; Chindaprasirt and Rukzon, 2008).
Increases compressive strength and decreases leachability(El-Dakroury and Gasser, 2008).
Reduces material cost and emission of CO due to less cement utilization (Saraswathy and Song, 2007).
Improves consistency of OPC-RHA blended paste environmental management as well as with increasing RHA % (Singh et al., 2002).
RHA could be used as an alternative source for high surface area silica (Della et al., 2002).
Among the pozzolans (slag, silica fume, fly ash) RHA has the ability to contribute to gain early strength (Mehta and Folliard, 1995).
The different sizes of RHA Nano silica gives a different effect to porous concrete strength (Abu Bakar et al., 2010; Ramadhansyah et al., 2012; Wan Ibrahim et al., 2014; Ramadhansyah et al., 2014; Lun, 2015; Mohd Ibrahim et al., 2017).