Air pollution occurs due to the presence of undesirable solid or gaseous particles in the air in quantities that are harmful to human health and environment. It can be defined as presence of foreign matter either gaseous or particulate or combination of both in the air which is detrimental to the health and welfare of…
The following terms are used in direct method of levelling: (i) Plane of Collimation: It is the reduced level of plane of sight with respect to the datum selected. It is also known as ‘height of instrument’. It should not be confused with the height of telescope from the ground where the instrument is set. (ii)…
Types of defects in plaster This post describes 7 different categories of defects most frequently noticed in plaster (as mentioned below) 1. Non-structural cracks 2. Structural cracks 3. Debonding 4. Lack of hardness 5. Grinning 6. Expansion 7. Popping The causes and repair methods for each are discussed below. 1. NON-STRUCTURAL CRACKS Crazing Crazing is a network of fine cracks, usually in a hexagonal…
Introduction Land filling is the most common and environmentally safe method of disposal for the fractions of municipal solid waste (MSW) that cannot be reduced, recycled, composted, combusted or processed. Open dumping of MSW, which is practiced by about three-fourths of the countries and territories in the world is a primitive stage of landfill development…
Gravity walls can be helped by reinforcement of the wall itself during its building or even by the use of anchor bolts, geotechnical material in the earth or material being retained, and gabions among other means. Gravity Retaining Wall Basics It is sometimes necessary to maintain level differences in adjacent areas of a project so…
In order to achieve a complete shape description, it is necessary to get more than one projection, and therefore, additional planes of projection are used to project more views on them, for the object. As such, the orthographic system of projection is also called multi-view projection method. In the orthographic projection drawing, for getting the…
The jackhammer is a versatile drill that may be powered hydraulically, electrically, or pneumatically. It is used for drilling rocks, breaking pavement, and other work that needs violent hammering. It functions like a chisel and hammer by poking with the bit, and not a rotary motion. Basics of Jackhammers Jackhammers are drills that are generally…
Kinematical analysis of a structure can also be done using the static equations. The following criteria for instantaneously changeable systems may be used: (a) Load has finite quantity but the internal forces have infinite values (b) Load is absent and the internal forces are uncertain (type of 0/0) Let us discuss these criteria for structure…
Plastering Applying mortar coats on the surfaces of walls, columns, ceiling etc. to get smooth finish is termed as plastering. Mortar used for plastering may be lime mortar, cement mortar or lime-cement mortar. Lime mortar used shall have fat lime to sand ratio of 1 : 3 or 1 : 4. If hydraulic lime is used mix…
If the theory of consolidation, presented in the previous chapters, were a perfect description of the physical behaviour of soils, it should be rather simple to determine the value of the coefficient of consolidation cv from the data obtained in a consolidation test. For instance, one could measure the time at which 50 % of…