This study assessed the geotechnical suitability of eroded soils from active gully erosion sites across South Eastern Nigeria for the production of sustainable compressed earth bricks (CEBs), establishing a laboratory proof-of-concept for the dual valorization of a significant environmental liability as an affordable construction material resource. Soil samples were individually collected and geotechnically characterized from fifteen active gully sites (three per state, spanning all five states of the South Eastern geopolitical zone) at standardized depths of 0.5 to 1.5 m, with tests including particle size distribution, Atterberg limits, standard Proctor compaction, California Bearing Ratio (CBR), and unconfined compressive strength (UCS) conducted in accordance with BS 1377 and ASTM standards. Stabilization trials and brick production tests were subsequently conducted on a representative pooled sample reflecting the predominant high-sand composition of the region, which presents the most challenging stabilization scenario. Three stabilizer categories were evaluated: Portland cement (5, 7.5, and 10%), hydrated lime (5 and 8%), and xanthan gum biopolymer (1, 2, and 3%), with CEBs produced using a hydraulic press at 10 MPa compaction pressure and tested after 7 and 28 days of curing, with three replicates per treatment per curing age. Individually characterized eroded soils exhibited predominantly sandy textures (55–92% sand content) and low-to-moderate plasticity indices (5.3–24.8%), varying in suitability for CEB production across states. Portland cement stabilization at 7.5% and above consistently produced CEBs meeting NIS 87 minimum standards for the representative test soil. The combination of 7.5% Portland cement and 1% xanthan gum biopolymer yielded the highest mean compressive strength of 4.18 MPa (± 0.21 MPa) at 28 days, with a water absorption rate of 10.6% (± 0.6%), satisfying the Nigerian Industrial Standard NIS 87 minimums of 2.5 N/mm2 and 15% respectively, and meeting ASTM C62 Grade MW requirements – outperforming 10% cement alone (3.82 MPa, 12.4%) at a lower cement dosage. Shapiro-Wilk tests confirmed normality (W: 0.893–0.961), Levene’s test confirmed homogeneity of variance (F(9,20) = 1.24, p = 0.283), and one-way ANOVA confirmed significant treatment effects (F(9,80) = 48.64, p < 0.001, ηp2 = 0.845). Regression analysis identified cement content as the dominant strength predictor (β = 0.712, R2 = 0.874) with a statistically significant cement–xanthan gum synergy interaction term (β = 0.318, p = 0.004). These laboratory findings demonstrate that appropriately stabilized eroded soils with sandy profiles characteristic of South Eastern Nigeria can yield structurally viable CEBs meeting national and international performance standards. Field-scale validation, life-cycle cost and carbon assessment, and long-term durability monitoring under South Eastern Nigerian climatic conditions are recommended before broader deployment conclusions can be confirmed.

Assessing the geotechnical properties of eroded soils for sustainable compressed earth brick production in Nigeria

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发表日期：

2026年7月20日

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Sopuruchukwu Chikere Ike,
Victor Arinzechukwu Okanya

摘要

This study assessed the geotechnical suitability of eroded soils from active gully erosion sites across South Eastern Nigeria for the production of sustainable compressed earth bricks (CEBs), establishing a laboratory proof-of-concept for the dual valorization of a significant environmental liability as an affordable construction material resource. Soil samples were individually collected and geotechnically characterized from fifteen active gully sites (three per state, spanning all five states of the South Eastern geopolitical zone) at standardized depths of 0.5 to 1.5 m, with tests including particle size distribution, Atterberg limits, standard Proctor compaction, California Bearing Ratio (CBR), and unconfined compressive strength (UCS) conducted in accordance with BS 1377 and ASTM standards. Stabilization trials and brick production tests were subsequently conducted on a representative pooled sample reflecting the predominant high-sand composition of the region, which presents the most challenging stabilization scenario. Three stabilizer categories were evaluated: Portland cement (5, 7.5, and 10%), hydrated lime (5 and 8%), and xanthan gum biopolymer (1, 2, and 3%), with CEBs produced using a hydraulic press at 10 MPa compaction pressure and tested after 7 and 28 days of curing, with three replicates per treatment per curing age. Individually characterized eroded soils exhibited predominantly sandy textures (55–92% sand content) and low-to-moderate plasticity indices (5.3–24.8%), varying in suitability for CEB production across states. Portland cement stabilization at 7.5% and above consistently produced CEBs meeting NIS 87 minimum standards for the representative test soil. The combination of 7.5% Portland cement and 1% xanthan gum biopolymer yielded the highest mean compressive strength of 4.18 MPa (± 0.21 MPa) at 28 days, with a water absorption rate of 10.6% (± 0.6%), satisfying the Nigerian Industrial Standard NIS 87 minimums of 2.5 N/mm² and 15% respectively, and meeting ASTM C62 Grade MW requirements – outperforming 10% cement alone (3.82 MPa, 12.4%) at a lower cement dosage. Shapiro-Wilk tests confirmed normality (W: 0.893–0.961), Levene’s test confirmed homogeneity of variance (F(9,20) = 1.24, p = 0.283), and one-way ANOVA confirmed significant treatment effects (F(9,80) = 48.64, p < 0.001, ηp² = 0.845). Regression analysis identified cement content as the dominant strength predictor (β = 0.712, R² = 0.874) with a statistically significant cement–xanthan gum synergy interaction term (β = 0.318, p = 0.004). These laboratory findings demonstrate that appropriately stabilized eroded soils with sandy profiles characteristic of South Eastern Nigeria can yield structurally viable CEBs meeting national and international performance standards. Field-scale validation, life-cycle cost and carbon assessment, and long-term durability monitoring under South Eastern Nigerian climatic conditions are recommended before broader deployment conclusions can be confirmed.