What are deleterious substances in concrete?
Certain chemical contaminants such as soluble chlorides and sulphates, organic compounds such as mono- and polysaccharides, humic acid and lignins, and also soluble salts of lead, zinc, cadmium and tin, can retard the setting of cement, and hence affect the final strength and durability of concrete.
What are deleterious materials?
Deleterious materials (also known as prohibited materials) are materials that are prohibited for use in a project. This could be for a variety of reasons including: reliability. health and safety. structural stability/performance/physical integrity/life-expectancy of a project.
What does deleterious mean in biology?
harmful to health or well-being; injurious.
What is the FM of sand?
The Fineness Modulus (FM) of fine aggregates (sand) is an empirical figure obtained by adding the total percentage of the sample of a sand retained on each of a specified series of sieves, and dividing the sum by 100.
What is the specific gravity of sand?
2.65 to 2.67
Sand particles composed of quartz have a specific gravity ranging from 2.65 to 2.67. Inorganic clays generally range from 2.70 to 2.80. Soils with large amounts of organic matter or porous particles (such as diatomaceous earth) have specific gravities below 2.60.
What is deleterious matter?
What are the deleterious materials in concrete?
Commonly deleterious materials are organic matters, dust (materials passing through 75 micron sieve), clay lumps, shale, coal iron pyrites, friable particles, chert (weak in terms of freezing and thawing), etc. which are weak, soft and fine. They affect the properties of concrete in fresh as well as in hardened state and are undesirable.
What is a deleterious substance?
The substances, who affect harmful physically or chemically on the aggregates, are considered to be deleterious.
What are the types of harmful substances in aggregates?
6 Types of Deleterious Substances in Aggregate 1 Organic Impurities. Organic impurities interfere with the hydration reaction. 2 Clay. Clay may coat the surface of aggregates which impair bond strength between aggregate and cement paste. 3 Silt and crusher dust. 4 Salts. 5 Unsound Particles. 6 Alkali- Aggregate Reactions.
How do you analyze aggregates for deleterious properties?
Aggregates suspected of deleterious properties will be analyzed by physical, chemical, and petrographic properties. Most research aggregates will be characterized by the Aggregate Image Measurement System for shape, angularity, and texture. The Micro-Deval test can also be a tool to see how aggregates breakdown in the presence of water.