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Due to the high costs of traditional concrete materials in Nigeria, such as river sand, there is an increasing demand to explore alternative materials like laterite for fine aggregates. Although laterite is abundant in Nigeria, its full potential in the construction industry remains untapped. Previous studies have shown that partially replacing river sand with laterite produces concrete with competitive strength properties. This research aims to validate and extend these findings, evaluating the impact of different aggregate sizes (12 mm, 20 mm, and 40 mm) on the strength of concrete with 10% and 25% laterite replacements for fine aggregate. Results revealed that as the laterite percentage increased, compressive, flexural, and split tensile strengths decreased. While 0% and 10% laterite replacements met the required strength, the mix with 25% laterite fell short. Increasing maximum coarse aggregate size led to higher strengths, with 40 mm sizes exhibiting the highest, and 12 mm the lowest. Compressive strengths ranged from 22.1 to 37.6 N/mm 2 , flexural strengths from 4.07 to 5.99 N/mm 2 and split-tensile strengths from 2.93 to 4.30 N/mm 2 . This research highlights the need for meticulous mix design adjustments when using laterite, balancing workability with strength objectives. The developed regression models offer a valuable tool for predicting concrete properties based on mix parameters, providing insights for optimizing laterized concrete designs across diverse construction applications and supporting sustainable building practices.

Pervious concrete provides a tailored surface course with high permeability properties which permit the easy flow of water through a larger interconnected porous structure to prevent flooding hazards. This paper reports the modeling of the flexural properties of quarry dust (QD) and sawdust ash (SDA) blended green pervious concrete for sustainable road pavement construction using Scheffe’s (5,2) optimization approach. The simplex mixture design method was adapted to formulate the mixture proportion to eliminate the set-backs encountered in empirical or trials and the error design approach, which consume more time and resources to design with experimental runs required to evaluate the response function. For the laboratory evaluation exercise, a maximum flexural strength of 3.703 N/mm2 was obtained with a mix proportion of 0.435:0.95:0.1:1.55:0.05 for water, cement, QD, coarse aggregate and SDA, respectively. Moreover, the minimal flexural strength response of 2.504 N/mm2 was obtained with a mix ratio of 0.6:0.75:0.3:4.1:0.25 for water, cement, QD, coarse aggregate and SDA, respectively. The test of the appropriateness of the developed model was statistically verified using the Student’ t-test and an analysis of variance (ANOVA), and was confirmed to be acceptable based on computational outcomes at the 95% confidence interval. Furthermore, the scanning electron microscopy (SEM) and energy dispersive X-ray (EDX) were used to evaluate the morphological and mineralogical behavior of green prior concrete samples with various additive mixture compositions. The addition of QD and SDA, on the other hand, aided the creation of porous microstructures in the concrete matrix due to fabric changes in the concrete mixture, potentially aided by the formation of cementitious compounds such as calcium aluminate hydrate and calcium silicate hydrate.

This study explored the impact of elevated temperatures on the residual structural properties of concrete made with a non-conventional fine aggregate such as laterite and quarry dust. In regions prone to high temperatures, such as tropical climates, the structural integrity of concrete can be compromised when exposed to elevated temperatures. Concrete samples were subjected to high temperatures (250 °C) and compared with control samples tested under normal conditions. In this research, the concrete mix was altered by replacing fine aggregates with different combinations of laterite (Lat) and quarry dust (QD) at varying percentages: 10%Lat:90%QD, 25%Lat:75%QD, 90%Lat:10%QD, 75%Lat:25%QD, and 50%Lat:50%QD. The physical properties of the constituent aggregates, including sand, laterite, quarry dust, and granite, were assessed, and an experimental mix was designed. The concrete samples underwent curing for 3, 7, 14, and 28 days, and their mechanical properties, specifically compression and flexural strength, were analyzed. The results demonstrated that as the percentage of laterite in the concrete matrix increased, there was a linear improvement in performance in terms of density, sorptivity, and strength gain. The maximum compressive strength reached 32.80 N/mm 2 at 90% laterite replacement. However, flexural strength showed a different response, with the highest strength of 5.99 N/mm 2 observed at 50% laterite replacement, after which strength declined with further increases in the laterite ratio. For economic and engineering considerations, it is recommended to use 25% laterite replacement with sand to produce grade 30 concrete, while 50% laterite replacement is suitable for grade-25 concrete. Importantly, the study found that a temperature of 250 °C did not significantly affect concrete strength, with changes of no more than 5%, which is consistent with expectations for conventional concrete. Furthermore, this research suggests that an optimal laterite replacement range of 25–50% should be considered when using laterite in concrete production.

This study presents optimization of mechanical properties of quarry dust (QD) and saw dust ash (SDA) blended pervious concrete for sustainable road pavement construction with Scheffe’s (5, 2) simplex lattice design. This research will offer opportunity for the re-use and reutilization of waste materials to control indiscriminate waste disposal which endanger our environment and to achieve eco-friendly and sustainable green construction materials. The method provides analytical approach for factor levels optimization of a mixture design problem in respect of the response parameters whereby the number of model terms to be developed is influenced by the total number of components and the order of regression polynomial to fully explore the factor space. Laboratory works were carried out using the Scheffe’s formulated mixture ratios to evaluate the concrete’s strength properties after 28 days of hydration. According to the results of the optimization exercise and the derived responses, the maximum compressive strength is 21.71 MPa with a mix proportion of 0.55:0.8:0.25:3.55:0.2 for water, cement, QD, coarse aggregate, and SDA, respectively. However, minimum compressive response of 16.58 MPa was obtained with a mix proportion of 0.435:0.95:0.1:1.55:0.05 for water, cement, QD, coarse aggregate, and SDA, respectively. Furthermore, the mathematical model developed was statistically validated based on the results of analysis of variance and Student’s t test at 95% confidence interval. Hydraulic conductivity tests were then performed on the sample mixes at the five vertices of Scheffe's factor space, and the results showed a linear increase in the hydraulic conductivity value as the ratio of SDA and QD increased, indicating that the cavity content of the pervious concrete mixtures proliferates with minimum SDA and QD content of 2.833% and 3.683%, respectively. Spectrum electron microscopy and energy-dispersive X-ray (EDX) were also used to investigate the mineralogical and morphological constituents of pervious concrete samples with varying admixture mixture compositions. However, due to changes in the fabrics of the concrete mixture, boosted by the cementitious composites development such as calcium silicate hydrate and calcium aluminate hydrate, the cement-admixtures blend aided the concrete matrix in forming porous microstructures and enhanced its mechanical and permeability properties for road pavement applications.