This set of Basic Civil Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Damp Proofing”.
1. DPM stands for:
a) Damp Proof Material
b) Damp Proof Mix
c) Damp Proof Member
d) Damp Proof Membrane
Explanation: DPM is a membrane material applied to prevent dampness. It can be used for a DPC (Damp Proof Course). An example is laying a polyethylene sheet under concrete slabs.
2. If the soil is dry, DPC for ground floor consists of layer of:
b) Coarse sand
c) Fine sand
Explanation: Coarse sand layer of about 75-100mm thickness is provided over the entire area under the floor. Over this, a layer of plain concrete with a ratio of 1:4:8 of 100mm thickness is laid.
3. Dampness spreads upwards from ground only.
Explanation: Dampness does spread from the ground upwards. In addition to this, dampness can also spread from roof downwards due to rain water.
4. At roof slab level over the DPC, __________ are provided.
d) Rubber sheet
Explanation: Tiles are provided to reduce the dampness. The treatment of dampness at roof level involves treating parapet and roof slab. A PCC is provided on parapet, then DPC and then tiles on roof slab.
5. DPC materials can be classified into:
Explanation: The materials can be classified into 3 categories. They are flexible material, semi rigid materials and rigid materials.
6. DPC materials should ideally be flexible, where differential thermal movements occur.
Explanation: Although semi rigid and rigid materials can be used, flexible materials are the best. These do not tend to crack or puncture under differential thermal movements, between the material of roof and parapet.
7. Which of the below is an example of semi rigid DPC material?
a) Plastic sheeting
b) Cement concrete
Explanation: Plastic sheeting is an example of flexible material. Cement concrete and stone are examples of rigid materials.
8. For DPC at plinth level, which grade of concrete is used?
Explanation: Cement concrete is used to provide DPC at plinth level. 38-50mm thickness of M15 (1:2:4) cement concrete is provided and it serves the purpose under normal conditions.
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