Cracks in Hardened Concrete Cracking in concrete after setting occurs for a variety of reasons. The two most common forms of cracking in hardened concrete are crazing and drying shrinkage cracking. 1. Crazing This is best described as a network of very fine cobweb-like or alligator-skin cracks, which appear on the surface of concrete after … Read more
What is Efflorescence in Concrete? Efflorescence in concrete simply means appearance of white colored powdered material on the concrete surface. Efflorescence is the formation of salt deposits, usually white, on or near the surface of concrete after it has been finished and causing a change in the appearance. Light-coloured concrete shows the deposit much less … Read more
Need for Soil Sampling A satisfactory design of a foundation depends upon the accuracy with which the various soil parameters required for the design are obtained. The accuracy of the soil parameters depends upon the accuracy with which representative soil samples are obtained from the field. Sampling is carried out in order that soil and … Read more
Aggregates for Asphalt Concrete The amount of aggregates for asphalt concrete mixtures is generally 90 to 95 percent by weight and 75 to 85 percent by volume. Aggregates are primarily responsible for the load supporting capacity of a pavement. Aggregate has been defined as any inert mineral material used for mixing in graduated particles or … Read more
DESCRIPTION OF ROCK MASS CHARACTERISTICS Standardized geologic mapping and logging procedures should be used for describing rock mass characteristics. The types of information collected will depend on site access, extent of rock outcrops, and the criticality of the proposed structure to be constructed on or in the rock mass. A method proposed by the International … Read more
Core Recovery and RQD (Rock Quality Designation) The easiest way to characterize the amount of material recovered during rock coring is to calculate “core recovery” as the amount (i.e. length) of recovered material divided by the total length of the core run (presented as a percentage). Rock Quality Designation (RQD) is a modified core recovery … Read more
How to Select Soil & Rock Properties for Engineering Design? A rational approach for selecting soil & rock properties for engineering design can be summarized as a logical twelve-step procedure that covers the 3 primary stages i.e. Site Investigation and Field Testing, Laboratory Testing and Interpretation, and Engineering Design This step-by-step process is presented on … Read more
Essential Properties of Asphalt Concrete Mix design methods and design requirements form an essential part for all asphalt concrete mixtures. The agency or authority responsible for paving construction (Department of Transportation) usually establishes the mix design method and design requirements. Once these are established, it becomes the responsibility of the Contractor/Producer and his technician to … Read more
Joints in Rigid Pavement Provisions of joints are necessitated due to: 1) Expansion, contraction and warping of concrete slabs resulting from temperature and moisture changes; 2) Facilitate a break in the construction at the end of day’s work or for any unexpected interruption to work progress; and 3) Construction of pavements in lanes of convenient … Read more
Fly Ash Fly ash or pulverized fuel ash (PFA) is the residue from the combustion of pulverized coal collected by mechanical or electrostatic separators from the flue gases or power plants. It constitutes about 75 per cent of the total ash produced. The properties and composition of fly ash vary widely, not only between different … Read more