RANDOM RUBBLE MASONRY

1.   MATERIALS

A.  STONE:

Stone used shall be Basalt stone. It should have a minimum crushing strength of 400 kg/sq.cm. It should not absorb water more than 5% by weight. The stone shall be obtained from quarry approved by the Engineer/Architect. The stones shall be of such size as can be easily lifted and placed in position by a single worker. Rounded stones should not be used. Stones should be free from soft materials, cracks, veins and organic impurities.

B.  Cement:

Cement used shall be ACC 43 grade cement. The cement used shall be fresh (within 2 months from the date of manufacture)

C.  Sand:

Fine aggregate shall be river sand. It should be well graded. It should be free of excessive amount of silt (not more than 8%). It should not contain organic impurities. If the sand is wet it should be tested for bulking. If the sand has bulked, extra sand shall be added of the required percentage volume. Crushed stone can also be used as fine aggregate if allowed by the structural Engineer. The amount of crushed stone used as fine aggregate shall be as per the instructions of the Engineer.

D.  Water:

Water used shall be potable water. It should be free from organic and chemical impurities and excessive amount of salt. If in doubt the water shall be got tested from the laboratory.

2.   DRESSING:

The stones used shall be randomly picked to fit into the required position, The faces and the sides of the stones shall be roughly hammer dressed to ensure proper fit.  The stone shall be so placed as to ensure that no bushing of the stone projects more than 40mm from the face of the wall.

3.   LAYING:

The stones shall be laid in cement mortar 1:6 in such a way that the stones are properly bedded and no hollows or cavities are left. Smaller spaces between stones shall be filled with stones of smaller sizes (SPALLS). The stones shall be placed randomly but taking care to break joints in all the three directions. The line and level of the stonework shall be checked from time to time.

4.   THROUGH STONES:

Stones occupying the entire width of the wall shall be placed at approx.1meter apart  in elevation both in height and length of the wall.

5.   BONDERS:

Where width of the wall is large and through stones of required width are not available. Two stones overlapping each other shall be used (bonders.)

6.   SPALLS:

The gaps between stones is large it shall be filled with smaller stones (spals)

7.   MORTAR:

The mortar used shall be cement mortar of proportion 1:6

8.   MORTAR JOINTS:

The mortar joints between stones shall not exceed 20mm in thickness. Where ever plastering or pointing is to be done the joints shall be raked to a depth of 10mm when the mortar is still green (fresh)

9.   CURING:

The stone work shall be cured by spraying water for a period of minimum 7 days.

10.                SCAFFOLDING:

Single scaffolding shall be used where ever required

11.                MEASUREMENT:

The stone work shall be measured in cubic meters.