Specification of construction material in building

 Construction material code: - 

        Construction material is the materials used in the construction process of any kind of structure. The selection of construction material is very much important in construction in order to ensure the quality of the work. Some of the materials in building construction are shown below: -

1) Cement: -

         Cements stored more than two months from the date of receipt should either be avoided or tested in the lab. Cement should be ordinary Portland cement meeting the requirement of NS049-2041.

2) Coarse Aggregate: - 

        Shall consist of crushed or broken stones, shall be hard, strong, dense, and durable. Should be angular in shape, flankey elongated pieces shall be avoided. Aggregate should confirm the requirement if IS 383-1970 and IS515-1959.

Sizes: -

        a) Normal cement concrete with a thickness of 100mm and above graded from 20mm downward.

        b) Cement concrete from 40mm to 100mm thickness is graded from 12mm downward.

                                

                                                            
                                                            Fig: - Sand and Aggregates

3) Sand: -

        a) Shall consist of silicious material hard, strong and uncoated particles.

        b) Shall be free from dust, lumps, soft or flakey particles, shale, salts, organic matter.

        c) In no case shall the total of the undesirable substance exceed 5% by weight.

4) Bricks: -

        a) Should have minimum crushing strength of 3.5N/mm2.

        b) Standard size (240x115x57) mm with 10mm thick horizontal and vertical mortar joints is                       preferrable.

        c) Tolerance of -10mm on length, -5mm on width, -+3mm on thickness.

        d) Minimum wall thickness is half brick and a maximum thickness of one brick shall be used.

        e) Generally should not break when dropped from height of about 1m and should give clear ringing sound when striked with one another. ( Field testing of brick)

        f) Should be well burnt or shightly over burnt.

Fig: - Brick Dimension

5) Mortar: -

        Cement sand mixes of 1:6 and 1:4 shall be adapted for 1 brick and half brick wall. Freshly hydrated lime in a ratio of ¼ to ½ of cement can be added to the mortar which will highly increase the plasticity without reducing the strength of the mortar.

6) Plasters: -

        All the plasters should have the cement sand mix not leaner than 1:6. The mortar shall have 28 days cube test of 3KN/mm2.

7) Steel bars: -

        a) Reinforcement bars shall be clean and free from dust, rust, coats of paints, oils, grease or other                 coatings.

        b) It shall conform to the following NS specifications: -

            Mild steel bars conforming to NS 85-2042 with fy=250N/mm2.

            Higher deformed bars conforming to NS: 191-2046 with fy= 415 N/mm2 or fy= 500 N/mm2.

NOTE: -

        i) According to MRT, fy=415 N/mm2 steel is assumed for main bars in beams and columns.   For using any other steel with a lower value of fy, the area of steel shall be correspondingly increased.

        ii) High strength bars fy= 500 N/mm2 may be used as reinforcement in slabs.

        iii) 7 dia of Fe 500 can be replaced by 8dia bars of Fe415.

All datas are according to Nepal Building Code (NBC 109: 1994)

            Prepared  By: - Er. Biplov Sapkota

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