This paper highlights a preliminary study on the potential of a tipping flush gate to be used in an open storm drain to remove sediment. The investigation was carried out by using a plasboard model of the tipping flush gate installed in a rectangular flume. A steady flow experiment was carried out to determine the discharge coefficients and also the outflow relationship of the tipping flush gate. The velocity produced by the gate at various distances downstream of the gate during flushing operation was measured using a flowmeter and the velocity at all the points was higher than the recommended self-cleansing design available in the literature. A preliminary experiment on the efficiency of flushing was conducted using uniform sediment with d50 sizes of 0.81, 1.53 and 4.78 mm. Results generally showed that the number of flushes required to totally remove the sediment from the initial position by a distance of 1 m increased by an average of 1.50 times as the sediment deposit bed thickness doubled. An equation relating the number of flushes required to totally remove the sediment bed for 1 m with the sediment bed deposit thickness was also developed for the current study.
The current study aims to verify the existing equations for incipient motion for a rigid rectangular channel. Data from experimental work on incipient motion from a rectangular flume with two different widths, namely 0.3 and 0.6 m, were compared with the critical velocity value predicted by the equations of Novak & Nalluri and El-Zaemey. The equation by El-Zaemey performed better with an average discrepancy ratio value of 1.06 compared with the equation by Novak & Nalluri with an average discrepancy ratio value of 0.87. However, as the sediment deposit thickness increased, the equation by El-Zaemey became less accurate. A plot on the Shields Diagram using the experimental data had shown the significant effect of the sediment deposit thickness where, as the deposit becomes thicker, the dimensionless shear stress θ value also increased. A new equation had been proposed by incorporating the sediment deposit thickness. The new equation gave improved prediction with an average discrepancy ratio value of 1.02.
The understanding of how the sediment deposit thickness influences the incipient motion characteristic is still lacking in the literature. Hence, the current study aims to determine the effect of sediment deposition thickness on the critical velocity for incipient motion. An incipient motion experiment was conducted in a rigid boundary rectangular flume of 0.6 m width with varying sediment deposition thickness. Findings from the experiment revealed that the densimetric Froude number has a logarithmic relationship with both the thickness ratios ts/d and ts/y0 (ts: sediment deposit thickness; d: grain size; y0: normal flow depth). Multiple linear regression analysis was performed using the data from the current study to develop a new critical velocity equation by incorporating thickness ratios into the equation. The new equation can be used to predict critical velocity for incipient motion for both loose and rigid boundary conditions. The new critical velocity equation is an attempt toward unifying the equations for both rigid and loose boundary conditions.
The use of sustainable materials in the construction industry has been on the rise recently. Studies have proven that the use of conventional concrete and its raw materials has a negative impact on the environment. Research on incorporating biochar as a supplementary cementitious material has been recently evolving and has shown that the attributes of biochar are highly affected by the pyrolysis parameters. These attributes have enhanced the properties of biochar concrete and mortar composite. This paper identifies the different physiochemical properties exhibited by palm kernel shell biochar through optimization by response surface methodology. Focusing on some of the properties of biochar that have proven beneficial when used as a cement replacement. Very limited research has used optimization tools for the production of biochar with the intention of using it as a cement substitute. Pyrolysis was conducted by a tubular furnace at different temperature ranges from 200 °C to 800 °C. The biomass and biochar have been analyzed with TGA and FESEM-EDX. The targeted biochar properties and selected responses are the yield, carbon, oxygen, silica, and potassium content. The optimized parameters obtained are 409 °C, 15 °C/min, 120 min with responses of 38.2% yield, 73.37% carbon, 25.48% oxygen, 0.39% potassium and 0.44% silica. Thermal properties of the palm kernel shell biochar affected by the pyrolysis factors such as temperature, heating rate and residence time have also been discussed. In conclusion, this study supports and encourages the use of palm waste, which is abundant in Malaysia, as a supplementary cementitious material to promote sustainable growth in construction.