Civil boost

 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 linear relationship. Thank you. Gracious !

 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 force does not

 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.