Abstract
This study devotes to investigate the use of Raw Sewage Sludge (RSS) and Rice Husk Ash (RHA) to obtain sustainable construction materials. This study focuses on the evaluation of using cement-based materials having RSS and RHA. The methodology of this study could be summarized by replacing water by RSS and replacement of 10 %RHA from the weight of cement. Five groups have been used with different ratios of RSS/binder; for each group with and without RHA. In addition, the sand/binder ratio has been changed for Group 2. This method includes testing the flowability, compressive strength, Total Water Absorption (TWA) and density for the mortar mixes containing these materials. The results indicate that mixes with added materials encourage the results compared to control mixes. Addition of RHA considerably decreases flowability; however it enhanced compressive strength for all groups especially for Groups 3, 4 and 5. Moreover, the minimum values of TWA were recorded when 10% RHA was utilized as a cement replacement for both RSS and water mixes. Finally, it was found that replacing RSS by water, leads to the reduction in flowability and TWA in all mixes especially at 10% RHA; whereas the strength and density increase.
Highlights
To reduce the cost of concrete construction, different studies are trying to figure out alternatives for the ingredients of concrete without a significant reduction in its strength [1]
For Groups III and IV, the results pointed out that the density increased when using 10% of Rice Husk Ash (RHA) as a cement replacement comparing with the mix of no cement replacement ( 0% cement replacement) and the highest density was observed for Raw Sewage Sludge (RSS)/Binder ratio of 0.6 (MX6)
This figure indicates a tendency in the Total Water Absorption (TWA) with RSS ratio, as TWA raised as RSS ratio raised and the minimum TWA was implemented for MX1
Summary
To reduce the cost of concrete construction, different studies are trying to figure out alternatives for the ingredients of concrete without a significant reduction in its strength [1] These could be sustainable materials such as RHA and RSS. Siddika et al [1] concluded that using RHA as partial replacement of cement reduces environmental pollutants and economy in concrete construction They found that 10% RHA replacement gives the best values of compressive, flexural and tensile strengths. The RHA is considered as superior to other supplementary materials such as slag, silica fume and fly ash because they have high pozzolanic activity in addition, both strength and durability of concrete are enhanced [12]. This further develops strength, impermeability and durability by enhancing the transition zone, improving the pore structure, and preventing large voids in the hydro-cement paste through the pozzolanic reaction
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