Concrete ke liye kitna cement, reti aur aggregate?

Slab, footing, ya column — wet volume mil gaya to baaki arithmetic hai। Yeh guide batati hai ki Indian estimators volume ko cement bags, reti (cft), aur aggregate (cft) mein kaise split karte hain, aur supplier ko call karne se pehle material cost ka ballpark kaise nikalein।

Kya chahiye

Teen dimensions (ya agar volume pehle se hai to seedha volume):

1. Lambai (Length)
2. Chaudai (Width)
3. Depth / motai (Thickness)

Aur drawing se concrete grade — ghar ki slabs ke liye aksar M20, bhari load ke liye M25, PCC / lean concrete ke liye M15 ya M10।

Units consistent rakhein। Feet/inches ko metres mein convert karke multiply karein (ya poora feet mein kaam karein)।

Step 1: Wet volume

Wet volume = length × width × depth

Example: 3 m × 3 m slab, 100 mm (0.1 m) moti।

Wet volume = 3 × 3 × 0.1 = 0.9 m³ (~31.8 cft)

Yeh woh space hai jahan finished concrete baithti hai — order ki hui reti aur gitti ka loose pile nahi।

Step 2: Dry volume (× 1.54)

Materials dry measure hote hain। Site practice wet volume ko 1.54 se multiply karti hai:

Dry volume = wet volume × 1.54

0.9 m³ ke liye: 0.9 × 1.54 = 1.39 m³ dry volume

1.54 factor particles ke beech voids, paani milne par shrinkage, aur thodi wastage cover karta hai। Iske bina har baar kam order hota hai।

Step 3: Mix ratio se split

Har grade ka fixed nominal ratio (volume se cement : reti : aggregate):

| Grade | Ratio | Total parts | |-------|-------|-------------| | M10 | 1 : 3 : 6 | 10 | | M15 | 1 : 2 : 4 | 7 | | M20 | 1 : 1.5 : 3 | 5.5 | | M25 | 1 : 1 : 2 | 4 | | M30 | 1 : 0.75 : 1.5 | 3.25 |

M20 ke liye (residential slabs mein common):

• Cement = dry volume × (1 ÷ 5.5) = 1.39 × 0.182 ≈ 0.25 m³
• Reti = dry volume × (1.5 ÷ 5.5) ≈ 0.38 m³
• Aggregate = dry volume × (3 ÷ 5.5) ≈ 0.76 m³

Step 4: Bags aur cft mein convert

Indian cement bags 50 kg hain। ~1440 kg/m³ bulk density par ek bag ≈ 0.0347 m³।

Cement bags = ceil(cement m³ ÷ 0.0347)

0.25 ÷ 0.0347 ≈ 7.2 → 8 bags

Reti aur aggregate local supplier se aksar cft mein order hote hain:

cft = m³ × 35.3147

• Reti: 0.38 × 35.3 ≈ 13.4 cft
• Aggregate: 0.76 × 35.3 ≈ 26.8 cft

Step 5: Rough material cost

Cost fixed nahi — sheher, season, aur haul distance se badalti hai। Simple first pass:

Cost ≈ (bags × ₹/bag) + ((reti cft + aggregate cft) × ₹/cft)

Agar cement ₹400/bag aur reti+aggregate combined ₹55/cft:

8 × 400 + (13.4 + 26.8) × 55 ≈ 3,200 + 2,210 ≈ ₹5,410 sirf materials ke liye

Steel, shuttering, mazdoori, aur pump hire alag hain। Yeh number cement, reti, gitti order ke liye hai — poori slab ka turnkey cost nahi।

Worked summary (3 m × 3 m × 100 mm, M20)

| Item | Value | |------|--------| | Wet volume | 0.9 m³ (~31.8 cft) | | Dry volume (×1.54) | 1.39 m³ | | 50 kg cement bags | 8 bags | | Reti | ~13 cft | | Aggregate | ~27 cft | | Rough material cost | ~₹5,000–6,000 (rates vary) |

Manual math skip karein — Cement Reti Aggregate Calculator se turant result. Dimensions m ya ft mein, M10–M30 choose karein, local rates ke liye ₹/bag aur ₹/cft edit karein।

Kab use karein vs slab calculator

Dono tools simple rectangular slab par overlap karte hain। Yeh calculator tab use karein jab reti aur aggregate alag-alag chahiye editable per-material rates ke saath, ya shape box hai par kaam footing, column, ya beam hai floor slab nahi। Quick slab estimate with ready-mix ₹/m³ range ke liye slab ke liye cement calculate dekhein।

Practical tips

• Cement bags hamesha upar round karein, neeche kabhi nahi।
• Structural drawing par grade confirm karein — engineer ki marzi ke bina M20 ko M25 mat badlein। M20 vs M25 compare karne ke liye padhein।
• Reti aur aggregate aise supplier se order karein jo site par alag stacks deliver kar sake — materials kam hone par ratio bigad jati hai।
• Irregular shape, steps, ya uneven shuttering par 5–10% extra rakhein।

FAQ

Footing ya column ke liye use kar sakte hain?

Haan। Koi bhi rectangular wet volume: footing L × W × D, ya column plan mein square/rectangle × height। Irregular shape: boxes mein todo, volumes jodo, phir 1.54 aur grade ratio lagao।

M20 mein aggregate reti se lagbhag double kyun?

Nominal mix 1:1.5:3 mein aggregate reti se double volume (3 vs 1.5 parts)। Site par concrete zyada tar patthar hoti hai, cement nahi।

Isme steel aur mazdoori hai?

Nahi। Yeh material quantity aur material-only cost hint hai। Site par RCC slab cost aksar 60–70% mazdoori, steel, formwork — materials ek line item।

M15 vs M20 — bags mein kitna farq?

Same volume par M15 (leaner) mein M20 se kam cement bags — cement mix ka chhota hissa hai। Hamesha drawing grade follow karein; grade kam karke bags bachana safe nahi।

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Slab ke liye cement-only shortcut? Slab ke liye cement kaise calculate karein padhein। Saari Hindi guides dekhein, ya grades compare karne ke liye M20 vs M25।