Rock Civil Blog

Bolted Joints:- Bolts may be used in place of rivets for structure not subjected to vibration. The following types of bolts are used in structure. Unfinished bolts:- These types of bolts are also called as ordinary, Common, rough or black bolts. These are commonly used in light structure subjected primarily to static loads and for secondary members like purlins, bracings etc. These bolts are made from low carbon steel (circular rods) by forging process. High strength bolts:- High strength bolts are fabricated from bars if medium carbon heat treated steel and from the alloy steel. There high strength is obtained from the quenching process followed by the tempering process or by the allowing steel.

Hoisting Equipment:- Hoisting is the operation of lifting the load. Hence equipment used for hoisting purpose lift the load from the place, hold it in suspension during transfer from one location to the other and Finley place it on the desired location. Types of hoisting Equipment (1) Pulley:- Pulley and sheave are used for lifting rough surfaced and heavy objects. Both chains and wire ropes are used for this purpose. (2) Chain Hoists:- It is used for lifting loads up to 50 tonnes. The system consists of hand chain and the load chain. The pull applied through the hand chain is transmitted to The load chain with a multiplication factor of over 20. (3) Winch:- A winch is a combination of gears (spur and pinion), Clutches and brakes. The operation is controlled through a serie of levers. It is commonly used in lifting the railways gates. (4) Cranes:- Cranes are most widely used equipment as an independent unit. Lifting capacity varies from 0.5 tonne to 500 tonnes.

Impurities in Limestones 1. Magnesium Carbonate:- The magnesium Limestones are hard, heavy and Compact in texture. The magnesium Limestones display irregular properties of calcination, Slaking and hardening Upto 5% of magnesium oxide imparts excellent hydraulic in properties to the lime 2.Clay:- It is mainly responsible for the hydraulic properties of lime. The percentage of clay to produce hydraulicity in lime stone usually varies from 10 to 30. Limes Containing 3-5 percentage of clay do not display any hydraulic properties and do not set and harden under water. 3.Silica:- In its free from it has a detrimental effect of the properties of lime. 4.Iron Compounds:- Iron occurs in small proportions as oxides, carbonate and sulphides. Pyrite or iron sulphides is regarded to be highly undesirable. For hydraulic limes 2-5% of iron oxide is necessary. 5. Sulphates:- Sulphates if present slow down the Slaking  action and increase the settings raye of limes. 6. Alkalis:- When pure lime is r...

Classification of Limes:-               (1) Fat Lime              (2) Hydraulic Lime              (3) Poor Lime or Lean Lime ( 1) Fat Lime:- This lime is also known as the high calcium lime.pure lime, rich lime or white lime. It is popularly known as the fat lime as it slakes vigorously and its volume is increased to about 2-2.5 times the volume that of quick lime. The impurities in such limestone is less than 5%. (2) Hydraulic Lime:- This lime is also known as the water lime as it sets  under water. It contains clay and some amount of ferrous oxide. The hydraulic lime can set under water in thik walls where there is  no free calculation of air. (3) Poor Lime:- This Lime is also known as the impure or  lime. It contains more than 30% of clay . It slake very slowly. Lemon Limes

Test for mortar:- Adhesiveness to Building Units:- Mortar is  placed to join them so as to form a horizontal joint. If size of bricks is 19cm x 90cm x 90cm, a horizontal joint of 9cm x 9cm=81cm. square will be formed. Ultimate adhesive strength of mortar  per cm square area is obtained by dividing maximum load with 81cm square area. Crushing strength:- Brick masonry or stone masonry laid in mortar to be tested are crushed in connection machine. The load at which the masonry crushes gives the crushing strength. Tensile strength:- The briquettes are tested in a tention testing machine. Cross- Sectional area of central portion is 38mm x 38mm or 1444 mm square or 14.44cm square.

What is mortar:- Building mortar is defined as a mixture of Cement, Sand and Water.Mortar is similar to Connect but it doesn't contain coarse Aggregate.Mortar are used for filling joints as a binder in stone and brick masonry is called Mortar. as shown in fig below Bulking of Sand:- In the case of aggregate there is another effect of the presence of moisture viz.bulking  which is an increase in the volume of given  mass of sand (Fine Aggregate)Caused by the films of water pushing the sand partical a parts.For a moisture content of about 5-8% this increase of volume my be as much as 20-40% depending upon the grading of sand. As shown in fig below. Classification of Mortar:- Mortar are classified in the basis of the following:                   1. Bulk density                  2. Kind of binding materials                  3. Nature of application...