Evaluation of Volumetric Properties of Cassava Peel Ash Modified Asphalt Mixtures

In continuance to providing a reliable and cost-efficient road construction material that would aid the development of sustainable pavements while also eradicating agricultural wastes to protect the environment, Cassava Peel Ash (CPA) modified asphalt mixture is seen to be one of the most viable options. This study aimed to determine the suitability of Cassava Peel Ash (CPA) in hot mix asphalt for improved pavement performance. Using response surface methodology, a central composite design was employed for the mix design parameters, namely coarse aggregate (CA), fine aggregate (FA), mineral filler (MF), bitumen content (BC), and cassava peel ash (CPA). CPA was used as a partial replacement for filler and varied between 0% and 20%. The BC varied between 4% and 8%, the MF varied between 15% and 20%, the FA varied between 10% and 14%, and the CA varied between 46% and 52%. The interactive effect between the mix design parameters on the volumetric properties of the asphalt mixtures was evaluated. The results obtained showed the Marshall stability, flow, density, volume of the void, and void in mineral aggregates of the asphalt mixtures at 1.8037–8.045 kN, 2.7-8.22 mm, 2.0426–2.3909%, 1.094–7.966% and 55.5105–93.1393% respectively. These results indicate that the interaction of CA, FA, MF, BC, and CPA influences the volumetric properties of asphalt mixtures. From the RSM analysis, a prediction model and an optimal condition of 4.018% asphalt content, 20% cassava peel ash, 46% coarse aggregate, 10% fine aggregate, and 15% mineral filler were achieved for the asphalt mixtures. Doi: 10.28991/CEJ-2022-08-10-07 Full Text: PD

Mix ratio design assessment of interlocking paving stone using both destructive and non-destructive methods

Interlocking paving stones have been produced in most developing countries with no specific method for testing the strength before use. This study presented the mix ratio design assessment of interlocking paving stone strength properties using both destructive and non-destructive methods. Six mix ratios were used to produce the interlocks and tests such as skid resistance, flexural strength, compressive strength and rebound hammer were conducted on 7, 14, 28, 56 and 90 days. All the skid resistance tests had British Pendulum Number (BPN) values greater than 75 specified in Table NA.2 of BS 1338:2003, the interlocking paving stone potential for skid is extremely low. The flexural strength was conducted following IS 15658:2006 and the result ranges from 1.34 – 5.38 N/mm2. The compressive strength result for the mix ratios ranges from 6.20 – 21.78 N/mm2 and mix ratio 1:3 had the highest compressive strength of 19.34, 21.78 N/mm2 at 56 and 90 days respectively. Table 1 of IS 15658:2006 is used to classify the paving stone for use in non-traffic areas based on the compressive strength results. A correlation model was developed combining all the mix ratio average rebound values and compressive strength, the regression equation was produced and an accuracy test was performed to check the regression formula estimates. This study validates the use of a rebound hammer as a non-destructive method on interlocks to predict the compressive strength with 79 % accuracy. Mix ratio 1:3, 1:2 is recommended for use in producing interlocks based on higher compressive and flexural strength