**3.5 POC concrete as noise control materials**

Previous research show that reducing multiple sound reflections from building façades can be reduced by making them sound absorbing [40]. When considering NRC, the highest is given by 50% POC which dominated by SAC at 315 Hz and 1000 Hz of 0.5 and 0.36, respectively. Thus, based on this study the development of noise control materials for application on or as building façade can be based on SAC values exceeding 0.35 especially at 315 Hz and 1000 Hz. This is to address the problem of middle frequency range and dominant noise source from roads is

**Figure 18.** *Compressive mode of failures of specimens.*


#### **Table 2.**

*Noise control material suggestion.*

sufficient apart from sufficient strength 5 N/mm<sup>2</sup> . This means that concrete with a POC mixture of 50% replacing natural river sand has the potential to be used as masonry blocks that have sufficient strength and can absorb sound. This can replace application of conventional concrete having a SAC between 0.03 to 0.09 in the range of 400–4000 Hz as building façade [17]. A detailed summary of the properties and mixtures is shown in the **Table 2**.
