Chemical Seasoning and Preservatives of Wood
There are 3 main classes of preservatives Oily substances insoluble in water Water-soluble salts Salts carried in volatile solvent other than water. A) Oily Preservatives Coal-tar is the best known ►most widely used preservative Obtained from bituminous coal Available in many grades ► gives satisfactory results
Artificial Methods of Wood and Timber Seasoning
Kiln drying of lumber is perhaps the most effective and economical method available. Drying rates in a kiln can be carefully controlled and defect losses reduced to a minimum. Length of drying time is also greatly reduced and is predictable so that dry lumber inventories can often be reduced. Where staining is a problem, kiln drying is often the only reasonable
Storage of Cements at Site - Do's and Don'ts
Cement refers to material which acts as a binding substance. In construction and civil engineering cement is used to bind structural members for construction of buildings, pavements, bridges, tunnels, roads and highways etc. Cement bags should not be stored in an enclosed area where the walls, roof and floor is not completely weatherproof. Cement bags must not be
Uses and Applications of Different Types of Cement
Portland cement is a type of cement, not a brand name. Many cement manufacturers make Portland cement. Types IA, IIA and IIIA are cements used to make air-entrained concrete. They have the same properties as types I, II, and III, except that they have small quantities of air-entrained materials combined with them. Normal Portland cement. Type 1 is general use
Types of Cement & Characteristics of each Type
Type V: When concrete is exposed to highly alkaline soil or water having high sulphate content then this type is used. This cement has a low C3A content so as to avoid sulphate attack from outside the concrete. Otherwise the formation of calcium sulphoaluminate and gypsum would cause disruption of conrete due to an increase in volume of resultant compounds.Engineering Properties of Cement
Concrete is a compound material made from sand, gravel and cement. The cement is a mixture of various minerals which when mixed with water, hydrate and rapidly become hard binding the sand and gravel into a solid mass. The oldest known surviving concrete is to be found in the former Yugoslavia and was thought to have been laid in 5,600 BC using red lime
How to Manufacture Lime
For small quantity of limestone, burning is done in a clamp. On a clear surface about 5 meters in diameter, layers of broken limestones and fuel are laid to form a heap about 4 meters high. First and the last layers should be of the fuel. In case coal is used as fuel, it could be well mixed up with limestones and lay in a heap. Sides of the heap, which incline slightlyApplications of Fat lime in Engineering
It slakes rapidly. It consists of less than 5% of impurities such as silica and alumina (in clay form) and high %age of CaO. It is slow in setting and hardening and setting depends on CO2 from atmosphere, therefore rich lime is used for plastering but not mortar making. It may be used for inferior and temporary structures. It contains more than 5% clayey impuritiesEngineering Properties of Fat Lime
Fat lime is produced from sea shell, coral deposits etc or from lime stone containing impurities like free sand and soluble silica combined with alumina, magnesium, carbonate etc. If the proportion of free sand is large, the resulting lime becomes progressively poor and is called poor or lean lime. Fat lime slakes rapidly when water is added giving out considerableHydraulic Lime Uses & Applications
Feebly hydraulic lime contains less than 15% of silic and alumina. It slakes slowly. The expansion on slaking is small. It produces good mortar. Moderately hydraulic lime: It contains 15-25% of silica and alumina, slakes slowly with small expansion and is stronger than feeble type. It is suitable for good class of mortar, brick work and masonry. c. Eminently hydraulicProperties of Hydraulic Lime
Hydraulic lime is obtained from limestone or kankar, containing a very small %age of free sand and soluble silica combined with 10-39% of clay and magnesium carbonate. It also contains CaCO3. These components impart the property of Hydraulicity to lime. Hydraulic lime slakes very slowly (sometimes taking several hours even days to do so) without producingAcoustic and Sound Proofing Materials
Materials which have substantially greater ability to absorb sound than other conventionally used materials (wood, glass, concrete) are called acoustic materials. A majority of tiles used for acoustic purposes are made from wood, cane fibers matted and bonded into sheets of various thickness ranging from (3/16) in to (5/4)in. The sheets are cut into tiles of different sizes.
Aggregates - Types of Aggregates | Coarse Aggregate, Fine Aggregate
Aggregate is a granular material, such as sand, gravel, crushed stone, crushed hydraulic-cement concrete, or iron blast-furnace slag, used with a hydraulic cementing medium to produce either concrete or mortar. Those particles that are predominantly retained on the 4.75 mm (No. 4) sieve, are called coarse aggregates. Those particles passing the 9.5 mm (3/8 inch)Aluminous Cement or Calcium Aluminate Cements
This is the updated description for what used to be known as 'high-alumina cement' or HAC. The problem with this cement is that it is subject to what is known as 'conversion'.
