Browsing by Author "Iwu, Uchenna"

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    Models for predicting the compressive strenght of compressed stabilized earth blocks
    (Federal University of Technology, Owerri, 2025-07) Iwu, Uchenna
    This study presents models for predicting the compressive strength of compressed stabilized earth blocks (CSEBs). The blocks were produced using Ordinary Portland Cement (OPC) and suitable soil obtained by mixing laterite, river sand, and granite chippings in appropriate proportions. Varying OPC contents of 5%, 6% and 8% were used. A constant compressive pressure of 6MPa was used in molding all the blocks using universal compression machine. 27 mix ratios were used for the work, 18 for designing the models, and 9 for testing them. Three blocks were molded for each mix ratio, compressed, and cured by sprinkling of water twice daily and covering with nylon mat for 28 days, after which the blocks were crushed at saturated surface dry state. Using Ibearugbulem’s Regression Function, three mathematical models were formulated for predicting the compressive strengths of CSEBs when the mixture proportions are known. The average 28th day compressive strength values of the blocks for 5%, 6%, and 8% OPC content were 3.6N/mm2 , 5.5N/mm2 and 6.8N/mm2 respectively, well above the 2.5N/mm2 recommended by The Nigeria Industrial Standard (NIS 87: 2000) for load bearing walls. The compressive strength values predicted by model 2 at 5%, 6%, and 8% OPC content were 3.50N/mm2 , 5.53N/mm2 and 7.30N/mm2 respectively, while the corresponding laboratory values were 3.60N/mm2 , 5.50N/mm2 and 7.31N/mm2 respectively. Predicted and laboratory values for models 1 and 3 were similarly close. The predictions from the three models were tested with the statistical Fisher test and found to be adequate at 95% confidence level. Thus, the models are suitable for predicting the compressive strength of CSEBs compressed with a pressure of 6MPa