Laterite

In comparison with engineering, geology is a relatively new domain of know­ ledge. Man has been building almost from the moment he came down out of the trees or emerged from the caves. All of his structures were founded in or upon rock or soil. Before the end of what we call ancient history, he had learned a great deal about materials, mechanics, and structures. This empirical information had become an organized field of practical knowledge by the time of Leonardo da Vinci. Although both foundations and ma­ terials of construction were largely earthy, codified knowledge of neither one nor the other existed at that time. During the last two centuries, geology has emerged and has recently begun to take on a more quantitative aspect. A generation ago, it joined hands with civil engineering to create soil mechanics. Engineers began to apply the science of geology to foundations and materials with astoundingly successful results, and geologists began to acquire an understanding of engineering methods, applying what they could to their problems. Geologi­ cal engineering was born of this union. People of an older time employed stone and brick in construction, although cut brick and sawed stone were used more sparingly because of a scarcity in both suitable raw materials and techniques. They were used in Cambodia, for example. A material able to meet requirements was found nearby, known as itica culla. In India it was called vettu culla, but F. A.

Contenu

1. Genesis.- General.- Chemical Characteristics.- Environmental Conditions.- Chemical Action.- Physiography of Occurrence.- 2. Geology of Laterites.- Preparation of Soil Mantle.- Lateritization.- Induration.- Sedimentary Laterites.- Lateritized Gravel.- 3. Finding Laterites.- World Distribution and Map.- Identifying and Classifying Known Sources.- Defining Area of Need.- Terrain Keys.- Aerial Photographic Study.- Infrared Aerial Scanning.- Exploring Suspected Locations.- Field and Laboratory Identification.- 4. Uses of Laterite.- Evaluating Local Uses.- Building Material.- Road and Airfield Subgrade.- Base Courses and Wearing Surfaces.- Embankment for Dams.- 5. Construction Techniques.- Borrow Development.- Induration in Air.- Artificial Induration.- Placing Borrow Rock.- Crushing.- Compacting.- Testing Placed Materials.- 6. Maintaining Laterite.- Surfacing.- Road Surveillance.- Traffic Control.- Treatment.- Repairs.- References.