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Showing posts from March, 2020


The topic brick includes Composition of good brick earth, Harmful ingredients in brick earth, Factors affecting quality of bricks The all content is related to Indian standard of bricks. Composition of good brick earth: 1. Alumina It is the chief constituent of every kind of clay. Good brick earth and contain about 20 to 30% of alumina. It imparts plasticity to the earth it can be moulded. If alumina present in excess with inadequate quantity of sand, the raw brick shrink and warp during drying and burning. 2. Silica It exist in clay either as free or combined. Good brick earth contain 50 to 60% of silica. Presence of this constituent prevents cracking, warping, shrinkage and warping of raw bricks.  It imparts uniform shape to the brick. Excess of silica destroys cohesion between particles and the brick become brittle material. 3. Lime Small quantity of lime and exceeding 5% is  desirable. It should present in very finely powdered state. Lime prevent

Pycnometer method

Pycnometer is a 900 ml density bottle having conical brass top with 6 mm diameter and a hole at its center.  Pycnometer is used  to determine water content or specific gravity of a soil sample. Pycnometer cost or pycnometer price  varies from 500 to 1200 in Indian currency. Pycnometer is also a quickest method  that gives result in  10 to 20 minutes  to find water content of a soil sample whose specific gravity is known. Series of observation: Empty weight of the Pycnometer is initially noted as W1 200-400 gm of moist sample in case of water content and oven dried sample  to determine specific gravity is used. This sample is placed in the Pycnometer and is again weighted as W2. Empty volume of the Pycnometer is filled with water in multiple stages by subsequent removal of the air present in the sample either by the use of vacuum or by constant stirring of the sample. Mass of the Pycnometer after filling it with water in noted as W3. Now Pycnometer is completely emptied an

Sensitivity & thixotropy

Consistency of undisturbed sample of clay is altered even at same water content upon its remolding. This change in consistency (loss of strength of clay or decrease in degree of firmness of clay) takes  place due to following factors:- Due to permanent destruction of soil solids during remolding. Due to re-orientation of water molecules in the adsorbed layers of soil solids This loss of strength of soil is analyzed in terms of its sensitivity. Higher sensitivity soils mean high loss in strength of soil upon remolding. Hence, sensitivity denotes the degree of distribution of undisturbed sample of clay upon remolding at the same content. It is defined as the ratio of unconfined compressive strength of the soil in its undisturbed state to the unconfined compressive strength of the soil it its remolded state. Over a period of time, a part of the strength lost by the soil upon remolding is regained by it on the account of rehabilitation of the water molecules in the

Effect of compaction on engineering properties of soil / Effect of compaction on properties of soil

Effect of compaction on properties of soil or effect on engineering properties of soil  1. Structure Effect of compaction on structure is found to be more prominent in fine grained soils in comparison to coarse grained soils. With increase in water content at a particular compactive effort, orientation of the soil particles improves. Hence, structure on dry of optimum is found to be flocculent and wet of optimum is found to be dispersed. With increase in compactive effort, at same water content, orientation of soil particles also improves. Structure of C, B and D are more oriented than structure at A. Structure of C is more oriented than structure at A (Both Flocculent structure) 2. Permeability At the same compactive effort with increase in water content permeability reduces sharply on dry of optimum and on wet of optimum with increase in water content, it initially increases and then further starts decrease with increase in water content. The decrease in perme

Consistency of soils or Consistency limits

Soil consistency or consistency limit is meant the relative ease with  which soil can be deformed. This term is used for the fine grained soils as it denotes the degree of firmness of the soil which may be termed as soft,stiff or hard. Atterberg analyzed the consistency of soil in four stages Solid Semi-solid Plastic Liquid Consistency of the soil is related to its water content and the water content at which soil passes from one stage of consistency to another is termed as 'consistency limit' which are as follows: 1) Liquid limit It is defined as the minimum water content at which soil is in liquid state of consistency or it may also de defined as a minimum water content at which the soil has tendency to flow. From the point of view of determination of liquid limit, it may be defined as minimum water content at which a part of the soil cut by a groove of standard dimensions flows together by a distance of half inch (approx. 12mm) under the impact of 25 numb


Varnish is used to indicate the solution of resins or resinous substances prepared either in alcohol oil, turpentine Main object of varnishing on a wooden surface:- Brightens the appearance of the grain in wood and protect the painted surface from the atmospheric actions Renders brilliancy to the painted surface Protects the unpainted wooden surface of doors, windows, floors etc from the action of atmospheric agencies Characteristics of an ideal varnish: It should render the surface glossy Colour of varnish should not fade away when the surface is exposed to the atmospheric action It should not shrink or show cracks after drying It should dry rapidly and present a finished surface which is uniform in nature and pleasing in appearance The protecting film developed by varnish should be tough, hard and durable Ingredients of a varnish: 1) Resins or Resinous substance Commonly used resins are canal, lac, shellac Canal is a hard substance and available from th

Structure of tree

Tree basically consist of three parts i.e. trunk, crown, and roots. Function of trunk is to support the crown and to supply water and nutrients from the roots to the devices through branches and from leaves to the roots. Further subdivided in two parts: 1) macrostructure The structure of wood , visible to naked eye or at a small magnification is called the macrostructure. a) Pitch Inner molt, central position or core of the tree is called the pitch or medullar Vary in size and change for different trees b) Heart wood Inner annual rings surrounding the pitch constitute heart wood Dark in colour and imparts rigidity to the tree c) Sap wood Outer annual rings between Heartwood and cambium layer is known as sapwood It is light in weight and colour d) Cambium layer Thin layer of sap between  sapwood and inner bark is known as cambium layer If the bark is removed for any reason, then the surface of exposed and cells cease to be inactive resulting in the

Soil structures

The arrangement of the soil particles in soil mass constitute the soil structures which may be of following types: 1. Coarse Grained structure: This structure is found for the soils having size greater than 0.02mm (for coarse grained soil) Example: Sand and gravel In the formation of this structure, gravitational force plays the pre-dominant role and surface electrical forces as the result of which soil solids settle down under the effect of their own weight during deposition resulting in particle to particle contact. 2. Honey comb structure: This structure is formed for the soils having size of the particle in the range of 0.0002mm to 0.2mm Example: clay and silt In the formation of this structure, both gravitational and surface electrical forces play the equally important role as both are of almost same magnitude. When the particles settle down form the suspension during deposition surface electrical forces prevent these solids to roll down into new state of equili