This research work applies Scheffe’s second degree simplex theory to formulate a regression model for the optimization of the compressive strength of sandcrete blocks using cassava peel ash (CPA) blended Portland cement (OPC) as binder material for different mix ratios as multivariate functions with the proportions of the sandcrete block ingredients serving as variables. The experimental values of the compressive strength were obtained by performing destructive strength tests on the blocks after curing for 28 days, with a binder-aggregate ratio of 1:8 and water binder ratio ranging from 0.45 to 0.60, the OPC being replaced with CPA at 0 – 30% for the respective water-binder ratios. The optimization model from the Scheffe’s mixture method for a (4, 2) factor space was found to be y= f(x) = 1.95x1 (2x1-1) + 1.84x2 (2x2-1) +1.81x3 (2x3-1) +1.79x4 (2x4-1) + 6.08x1x2 + 5.72 x1x3 + 1.89 x1x4 + 7.28 x2x3 + 1.80 x2x4 + 7.16 x3x4. The model was tested using the student t- test at 95% accuracy and found to be accurate. Thus, the model can be used to predict any desired compressive strength value for CPA-OPC blended sandcrete blocks given any water-cement ratio between 0.45 and 6.0 and vice versa. Kathmandu University Journal of Science, Engineering and TechnologyVol. 13, No. 2, 2017, page:1-14

Soybeans husk was collected from a dump site, dried de-carbonated, separated into six samples and calcined at a temperature of 600 °C, for 1, 2, 3, 4, 5 and 6 hours respectively. Samples were taken for X- ray Florescence (XRF) analysis, Standard Electron Microscopy (SEM) imaging, setting time, standard water of consistency determination and specific gravity test. The result of XRF analysis revealed that the SHA contain less than 70 % SiO2+Al2O3+Fe2O3 stipulated by ASTM C618 for pozzolanas, but has very high CaO content. The SiO2 +Al2O3+Fe2O3 and CaO content though varies slightly with the calcination time of soybean husk. The specific gravity of SHA varies with calcination time of SH and ranges between 2.3 and 2.7 and is less than that of OPC irrespective of the calcination time. Setting times of OPC/SHA pastes at 10 % replacement of OPC with SHA increases with calcination time and is greater than that for OPC paste. The SEM analysis shows that the crystal structure of the SHA changes with calcination temperature. The compressive strength of mortar using OPC/SHA as a binder was determined after 7, 14 and 28 days curing and was found to be less than that for OPC mortars at all ages. However, the percentage reduction in strength decreased with curing age, with SHA calcined at 4 hours having the greater strength (i.e. 87.4 % of OPC strength at 28 days). The percentage gain in strength was more pronounced from 7 to 14 days. In all, SH calcined at 600 °C for 4 hours optimizes the pozzolanic potential of SHA.Kathmandu University Journal of Science, Engineering and Technology Vol. 12, No. I, June, 2016, Page: 13-22

Mathematical model of compression creep for Terminalia ivorensis (Black Afara) timber were developed and presented in this paper. One-year creep test was performed in this process on Terminalia ivorensis timber samples. The creep data were fitted to linear, exponential and logarithmic regression models. The coefficients of determination for each of the model was determined. The coefficients of determination of the linear, exponential and logarithmic models were determined as 0.689, 0.650 and 0.941 respectively. Since the logarithmic model has the highest correlation with coefficient of determination of 0.941, it gave the best compression creep prediction model for the Terminalia ivorensis timber.

This research work investigates the durability-based properties of a ternary calcined clay and limestone powder blended Self Compacting Concrete by measuring the short- and long-term permeation properties using water absorption and sorptivity properties testing. Also, the variation of compressive strength with age was evaluated at 7, 14, 28 and 56 days, while the split tensile strength was determined at 7 and 28 days curing. The Mineralogy and morphology of the ternary SCC was evaluated using FT IR Spectroscopy, SEM imaging and EDS. The results obtained shows that the ternary SCC showed improved durability and strength properties with age with dense and improved microstructure.