Home | ACIP Piling | Projects | Links | Terminology | About us

a tool having a helical shaft that is used for boring holes into the ground and removing the loosened soil

is a portion of a pile, which protrudes beyond the nominal diameter of the pile. This occurs when piles are bored through strata of soils with differing density. Bulging occurs when good practices are being observed.

an earthy material that is plastic when moist but hard when fired, that is composed mainly of fine particles of hydrous aluminum silicates and other minerals

is a term used to indicate that piles have been placed too close together while the concrete grout is still fluid. Visual observations of changes in levels of grout in the pile above or below the ground indicate the adjacent shaft may have expanded which may result in reduced shaft diameter of the other pile.

is a residue left over from burning coal. Most fly ash is pozzolanic, which means it’s a siliceous or siliceous-and-aluminous material that reacts with calcium hydroxide to form a cement. Properly selected fly ash reacts with the lime to form CSH–the same cementing product as in portland cement. This reaction of fly ash with lime in concrete improves strength. Typically, fly ash is added to structural concrete at 15-35 percent by weight of the cement.

Advantages
The most important benefit is reduced permeability to water and aggressive chemicals. Properly cured concrete made with fly ash creates a denser product because the size of the pores are reduced. This increases strength and reduces permeability. The reduced permeability helps to protect the concrete from chloride penetration, the cause of rebar corrosion (see Rosenberg’s article on corrosion in the Fall 1999 issue of MC Magazine).

Advantages in Fresh Concrete
Since fly ash particles are spherical and in the same size range as portland cement, a reduction in the amount of water needed for mixing and placing concrete can be obtained. The use of fly ash can result in better workability, pumpability, cohesiveness, ultimate strength, and durability.

Advantages in Hardened Concrete
Strength in concrete depends on many factors, the most important of which is the ratio of water to cement. Good quality fly ash generally improves workability or at least produces the same workability with less water. The reduction in water leads to improved strength.

a summary report of the exploration of the subsurface soils and how they are to be used as construction materials.

is a term that normally refers to the height in feet that the concrete grout is above the tip of the auger discharge bit as it is being withdrawn from the hole. While this can’t be measured because it is below the ground it is normally estimated by observing height the grout on the auger after it is totally withdrawn from the hole.

is a geological term which describes the conditions existing in limestone formations containing solution filled cavities and voids.

is a condition most feared by engineers and designers. Should the withdrawal rate of the auger exceed the replacement rate of the concrete pumped into the pile the soil may collapse and make the pile shaft smaller than nominal. In other cases shaft could be discontinuous. This could result is serious structural inadequacies.

is a condition when piles are placed though compressible strata where the skin friction on the pile above the compressible layer is considered to reduce the overall load carrying capacity of the pile.

is a term that refers to the amount of concrete used in excess of the Neat Line Volume of a cylindrical shaft of a given diameter.

Is the Estimated Volume of Concrete pumped divided by the Neat Line Volume of the pile. Most engineers specify a minimum of 115%.

is a theoretical condition which occurs when a continuous helical auger is rotated into the ground and excessive soil is removed . It is thought that this condition may cause a reduction in the soil density and thus a reduction in available skin friction between the soils and the pile surface. Over-flighting may be considered occurring when large depressions occur around the hole while it is being installed..

is a test to determine the safe load carrying capacity of a pile. A load is superimposed on a pile the load deflection and given intervals are recorded and analyzed. Reaction systems for applying loads to test pile can consist of weighed blocks or anchor piles with steel beams.

are steel reinforced concrete structures , normally square or rectangular, of a thickness which combine piles in groups to support singular columns above.

is thought to be the pressure that is required to maintain the shaft of concrete when extracting the auger during casting of the pile. There are varying beliefs on the pressure required and where the pressure should be measured. Because there are numerous factors which affect the line pressure such as , concrete consistency, height, length of supply hoses, location of gages and pump ability, there is not a known authority on this subject.

is a multiple of safety greater than 1 that is applied to the design load carrying capacity of a pile. Engineers and codes may specify the factor of safety depending on the structure that is being supported. Most codes require a safety factor of 2. This is sometimes increased depending on the amount of information available about the site.

is the sampling of soils using a standard procedure in which a sampler of a given size driven into the soil with a 140 pound hammer falling from a height of 30 inches. The number of blows of the hammer is recorded for each successive 6 inches of penetration for a total of 18 inches. The total number of blows for the last 12 inches is called the “N” Value. See ASTM.

The a graphical representation of the inferred subsurface soil strata recorded at depth with it’s corresponding “N” Value.

is normally expressed in Cubic Yards. It is calculated by multiplying 3.1416 times the radius squared times the length. The Neat Line volume is referred to as 100%.