Design of Non-load Bearing Concrete Hollow Blocks using Rice Husk Ash as Partial Replacement for Cement and Coconut Husk Fiber as Additives

In response to Lucena City's housing adversity, characterized by residents in exposed, makeshift dwellings, this study explored the potential of non-load-bearing Concrete Hollow Blocks (CHB) with Coconut Husk Fiber (CHF) and Rice Husk ASH (RHA). The study presented a cost-effective housing solution that promoted durability consequently decreasing environmental waste. Elaborating on compressive strength, studies revealed that the optimal inclusion rate of CHF for enhanced strength in concrete falls within 2% which suggested a potential tipping point that increasing fiber content might lessen strength. Additionally, researchers explored a CHF length of 4.5 cm for strength efficiency. RHA contributed positively as a cement replacement. However, increasing RHA content led to a reduction in strength . Notably, CHF exhibited workability in mixing concrete into prefabricated CHBs. This study ensured compliance with technical specifications by ASTM and ACI. Researchers adopted a cement-to-gravel-to-sand ratio of 1:3:6 with a water-to-cement ratio of 0.45. All designs incorporating RHA and CHF surpassed the compressive strength requirement of 3.45 MPa for non-load-bearing, type II non-moisture controlled CHB outlined in ASTM C129 and DPWH. The study suggested that CHF increased the strength of the CHBs. The data confirmed that the 5% and 10% RHA with 2% CHF mixes exceeded the control mix in strength having a water absorption of 12.47% and 12.82% respectively.