Factors Controlling Properties and Durability of Concretionary Laterite Gravel Aggregates

Inadequate understanding of the factors that control the strength and durability of concretionary laterite gravels constitutes a major constraint in the development of practical quality‐control specifications. This results in improper use of these aggregates in road construction, causing poor service performance. To remedy this situation concretionary laterite gravels from across Nigeria were subjected to several physical, mechanical, and chemical tests in the laboratory. The relationships between these tests and the major factors influencing the test results were determined by factor (R‐mode) analysis. The results of the study revealed that four principal component factors control the measured properties of laterite gravels. They are, in decreasing order of importance; (1) iron oxide content (degree of lateritization); (2) porosity and pore‐size distribution; (3) micropores; and (4) adsorbed water. These factors explain 79% of the total variance observed in the measured properties. The degree of lateritization accounts for 51% of the variance, and this indicates its dominating influence on the physical and mechanical properties of laterite gravel aggregates. The results of cluster analysis show that the parent material rock types also have considerable influence on the physicomechanical properties of laterite gravel aggregates and on the relative contribution of each factor group to the property variance.