Section 2: SITE WORK

MIL-HDBK-1011/1

2.1

Scope. This section covers earthwork, pile foundation systems,

paving, soil treatment, landscape work, and landscape irrigation systems.

General Design Considerations

2.2

Site Materials. The earthwork materials in the tropics are

2.2.1

dominated by three major groups: coral and coralline limestone, residual

soils, and rock aggregate. Because of the warm climate, high humidity, and

frequent rainfall, earthwork materials in the tropics are usually more

weathered and weaker than materials found in temperate regions. In addition,

erosion is a major problem. Therefore, for site work in the tropics, place

high emphasis on erosion control during design.

2.2.2

Site Investigation. When planning site work for heavy foundation

loads and important structures in coral and volcanic formations, site

investigation by exploratory borings is required. Ground-penetration radar

(GPR) can be used to locate shallow voids and cavities. Coral may have voids

and solution cavities. Volcanic rock formations also may have hidden lava

tubes and cavities. Therefore, the site selection as well as the type of

structure may well rest on the results of the exploratory borings. And, until

those results are known, no predetermination of building foundations or

foundation systems can be made.

2.3

Soil

2.3.1

Coral. Abundant in tropical regions, coral is a good subgrade

material. Reef coral is very dense, hard, and is an excellent source for

armor-rock in breakwater construction. Reef coral can also be crushed and

graded to produce good subbase and base course materials. Coralline sands and

gravels commonly found along the shoreline, being softer and more porous than

the reef coral, are usually only suitable as subgrade and subbase materials.

2.3.2

Coralline Limestone. Recrystallized coralline limestone can be

quarried and screened to produce aggregate suitable for subbase, base course,

and concrete aggregate. Coral concrete products generally have lower

compression strengths than concretes made with other types of rock aggregates.

It is important that coral used in concrete be free of salt. Washing of the

coral produces coral that is suitable for concrete mix, but in some areas lack

of adequate fresh water will make it difficult to get a thorough wash.

2.3.3

Residual Soils. Residual soils in the tropics are predominantly

silty clays and clayey silts. To be technically correct, the tropical

residual soils can generally be categorized into three major soil classes:

oxisols, andisols, and vertisols. Oxisols are by far the most common residual

soils in tropical regions. They cover approximately 50 percent of the land

areas in the tropics.

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