MORTAR NON SHOT NOTES TOPICS Flashcards
What is bulking of sand?
It is the increase in the volume of sand due to the presence of moisture.
Why does moisture cause an increase in the volume of sand? IN BULKING
Moisture forms a film of water around the sand particles, increasing the volume.
What is the percentage increase in volume for dry rounded fine aggregate with 5 to 8% moisture content?
For a moisture content of 5 to 8 percent, the increase in volume may be about 20 to 40 percent, depending upon the grading 0 of sand.
How does the grading of sand affect bulking?
The finer the material, the greater the increase in volume for a given moisture content.
What happens to the bulking of sand when more water is added?
Sand particles pack closer together, and the amount of bulking decreases.
PROPERTIES OF GOOD MORTAR
Good mortar should have strong adhesion, resist rainwater, be economical, durable, workable, quick-setting, crack-resistant, and compatible with materials. Key properties include mobility, placeability, and water retention.
Preparation of Cement Mortar (Summary)
Cement mortar is prepared by adding clean, impurity-free water to a mix of binding material and sand. Only potable water should be used. Mixing can be done manually or mechanically, with mechanical mixing preferred for large quantities.
Mixing in a Mechanical Mixer (Summary)
Cement and sand are dry-mixed in the mixer, followed by gradual addition of water. Wet mixing continues for at least one minute to achieve the desired consistency. Mortar should be prepared in quantities usable within 30 minutes, as it starts setting afterward.
Manual Mixing (Summary)
Sand is spread on a clean, dry platform, and cement is added on top. The ingredients are thoroughly mixed with a spade until a uniform color is achieved. The dry mix is then transferred to a shallow tank, and water is added to form a paste of the desired consistency. Each batch should be small enough to use within 30 minutes to prevent setting
What does IS 2250-1981 specify?
It is the code of practice for the preparation and use of masonry mortar
What does IS 13077-1991 specify?
It is the code of practice for the preparation and use of mud mortar in masonry.
Properties of Good Sand (Summar
Chemical Inertness: Should be chemically inert, not reactive.
Cleanliness: Must be free from impurities like vegetation and organic matter.
Grain Quality: Should contain sharp, angular, coarse, and durable grains.
Moisture Absorption: Should not contain salts that attract moisture.
Grading: Should be well-graded for better workability and strength.
Functions of Sand in Mortar (Summary)
Bulk: Sand adds bulk or volume to the mortar, making it more economical.
Strength: The proportion of sand adjusts the strength of the mortar, allowing for customization.
Shrinkage: Sand helps reduce shrinkage during drying, preventing cracks in the mortar as it set
