Civil boost

Creep is defined as gradual increase in strain without increase in stress with time. It is also known as plastic flow or time yield.   Creep may be due to viscous flow of cement-water paste or flow of water out of the cement resulting in the closure of internal voids. It also takes place due to readjustment of molecules. Factors affecting creep of concrete :- Influence of aggregate - aggregate shows a restraining effect on creep. stronger the aggregate, more is the restraining effect and less is the creep. Light-weight aggregate shows higher creep than normal weight aggregate due to lower modulus of elasticity.       2. Influence of mix design -  Creep increases with increase in w/c ratio. Creep is inversely proportional to the strength of concrete. Poor paste shows higher creep.            3. Age of concrete - Since quality of concrete improves with time. So older concrete is creepless whereas young concrete shows creep. After...

Objective - To find out the silt content in sand. Apparatus required -     A measuring cylinder (250 ml) Water Sand Theory - A good quality construction sand should has particles of 150µ to 4.75 mm. Particles smaller than this are classified as silt. The presence of excess quantity of silt in sand reduces the bonding capacity of raw materials and affects the strength and durability of work.  It is recommended to conduct silt content test  for every 20 ㎥ of sand. Procedure -  A 50 ml solution of 1% salt and water is prepared in the measuring cylinder. The sample of sand is then added to the cylinder until the level reaches 100 ml. 50 ml of the solution of 1% salt and water is again added to the measuring cylinder. The open end of the measuring cylinder is closed and then it is shaken well.  After 3-4 hours, it is noticed that a layer of silt is settle over the sand. Now the volume of silt layer settle over the sand is taken as v1. The volume of settle s...

 Abrahm's law expresses the relation between compressive strength of concrete mix and the  water-cement ratio which is taken in designing concrete mix.   This law states that the compressive strength of concrete mix is inversely related to its water/cement ratio.     If water/cement ratio (w/c ratio) increases, the strength of concrete decreases. He presented his classic law as :- S = A/B* where, S = compressive strength of concrete mix             * = water/cement ratio             A and B are constants.  The graph showing the relation between the strength and w/c ratio of the concrete mix is approximately hyperbolic shape.     The graph says, lower w/c ratio is taken when the concrete is vibrated for compaction and higher w/c ratio is required for hand compaction of concrete.   If we draw a line graph to show the relation between strength and c/w ratio , it shows approximately a li...

 Permeability is the property of a porous material which permits the seepage of water through its interconnecting voids. The flow of water through soil may either be a laminar flow or a turbulent flow. Darcy's law states that, " For laminar flow conditions in a saturated soil, the rate of flow or the discharge per unit time is proportional to the hydraulic gradient." V ∝ i V  ＝ ki where k is co-efficient of permeability. since, q =   AV = kiA q = discharge per unit time A = total cross-sectional area of soil mass i = hydraulic gradient V = Discharge velocity      If a soil mass of length L and cross -sectional area A is subjected to differential head of water ( ∆h), the hydraulic gradient i will be ∆h/L. And, q = k(∆h/L)A. When hydraulic gradient is unity, k = V. Thus, co-efficient of permeability is the average velocity of flow that will occur through the total cross-sectional area of soil under unit hydraulic gradient.  Thank you. Gracious !   ...

  LAP JOINT - In this joint, two members are overlapped and connected together. The load in lap joint has eccentricity because centre of gravity of load in both members are not in same line. Thus, a couple is formed which causes undesirable bending in the connection and the rivets may fail in tension. Also due to the eccentricity, the stresses are distributed unevenly across the contact area between the rivets and members to be connected.   BUTT JOINT - In butt joint, both members are placed end to end and additional plate/plates (cover plate) is provided on either one side or both sides and connected to the main plates. When one cover is provided, it is called single cover riveted butt joint and when double cover is provided,it is called double cover riveted butt joint.   It was the difference between lap and butt joint. Now, we will know superiority of butt joint. Butt joint is superior than lap joint because 1. In the case of a double cover butt joint, eccentricity of ...

 We  can visualize the all three columns on three basis - Their length Slenderness ratio Mode of failure. Short column :- Length ≤ 8 times of its least lateral dimension. Slenderness ratio = 0 - 32 Failed due to crushing. Intermediate column :- Length = 8 - 30 times of its least lateral dimension. Slenderness ratio = 32–120. Failed due to crushing and buckling combinedly. Long column :- Length > 30 times of its least lateral dimension. Slenderness ratio > 120 Failed due to buckling.