Detailed specification of cement sand mortar 1:6

Detailed specification: cement sand mortar 1:6

Scope: Preparation of cement sand mortar of 1 part cement to 6 parts sand by volume, for general brick masonry, stone masonry and similar work where moderate strength is needed.

Materials

• Cement: fresh OPC 43 grade/PPC conforming to the Nepal Standard/IS, free from lumps and moisture, stored on a raised platform in a dry shed.
• Sand: clean, hard, well-graded river sand, free from clay, silt (< 4%), mica, organic matter and salts; fineness modulus 1.5–2.5.
• Water: potable, free from oil, acid, alkali and organic matter.

Proportion: 1 : 6 by volume; cement measured as 0.035 m³ per 50 kg bag; sand in gauge boxes with allowance for bulking of damp sand. Approximate material for 1 m³ mortar: about 5.5–6 bags cement and 1.2 m³ sand (indicative).

Mixing

• Dry mixing of sand and cement until the colour is uniform, then add water slowly and mix to a workable, non-segregated paste, either in a mixer or on a watertight platform by hand (turned at least three times).
• The least water that gives workability should be used.

Use: Used within 30 minutes of mixing; stale mortar is rejected and re-tempering is not allowed.

Strength: 28-day compressive strength of standard mortar cubes about 3–5 N/mm², tested if asked by the engineer.

Measurement and payment: By volume (m³) when separate; otherwise included in the item rate.