Latitude of the position
STANDARD CONSISTENCY, INITIAL & FINAL SETTING TIME OF CEMENT
Aim: To determine (a) Normal Consistency, (b) Initial Setting Time & (c) Final Setting Time of given cement sample. Goal and Purpose: Cement when mixed with water forms paste which gradually becomes less plastic and finally a hard plastic is obtained. Cement Concrete should be placed in position of its use before it starts setting.
In the process of setting a stage is reached when the cement paste is sufficiently rigid to withstand a definite amount of pressure. The time to reach this state is termed as setting time. Setting time is divided into two parts Initial setting time and Final setting time. It is essential to keep suitable initial setting time for cement. Similarly when concrete placed in position it should get hardened as early as possible, So that the structure is put to use earliest. The time at which cement loses its plasticity or the process of hardening after which any crack developed in concrete will not reunite is termed as initial setting time and the time taken to reach the stage when the paste becomes a hard mass when concrete acquires sufficient strength is known as final setting time. For Ordinary Portland Cement (OPC) Initial setting time should not be less than 30 minutes and final setting time should not be more than 10 hours. The Standard Consistency, Initial setting time and Final setting time is determined with the help of Vicat’s Apparatus. It consists of a frame to which a movable rod is attached. An indicator is attached to the movable rod weighing 300 grams to measure the penetration. Vicat’s Apparatus consists of three attachments – square needle, plunger and square needle with annular collar used to determine initial setting time, standard consistency and final setting time of cement respectively. Apparatus: Vicat’s Apparatus, Measuring Jar, trowel, weighing balance, cement sample, stop watch. Precautions: 1. Sample should be selected carefully. 2. Weighing Machine should be calibrated. 3. Sieve Sets must be properly cleaned. No residue should be left. 4. Mechanical or Manual shaking must be done carefully so that no loss of material will be there.
COMPASS SURVEY
Aim: To perform Traverse surveying with prismatic compass, check for local attraction, and determine corrected bearing. Goal and Purpose:Compass surveying is a type of surveying in which the directions of surveying lines are determined with a magnetic compass, and the length of the surveying lines are measured with a tape or chain or laser range finder. The compass is generally used to run a traverse line.
The general principle on which the compasses work is the same for all types of compass. If a long and narrow magnetized iron or steel strip suspended on a pivot at its center is allowed to oscillate freely about its vertical axis passing through the pivot, it will always tend to assume a direction of the magnetic meridian at the place. Traversing Traversing is that type of survey in which a number of connected survey lines from the frame work and the directions and lengths of the survey lines are measured with the help of an angle measuring instrument and a tape or chain respectively.There are two types of traverse surveying.
Closed traverse When the lines form a circuit which ends at the starting point, it is known as closed traverse.
Open traverse
When the lines form a circuit ends elsewhere except starting point, it is said to be an open traverse.
Apparatus: Prismatic Compass, Tripod, Tape, Chain, Arrows, and Ranging Rods. Precautions:
