Fundamentals of Concrete Mix Design (Part 4): Concrete Mix Design Sample (ACI 211.1)

 Concrete Mix Design အကြောင်းအခြေခံ (၄)

Concrete Mix Design Sample (ACI 211.1)

ACI နည်းလမ်းဖြင့် နမူနာ Concrete Mix design တစ်ခုပြုလုပ်ကြည့်ပါမယ်။ ACI 211.1 မှာပါတဲ့ Table တွေအသုံးပြုပြီး assumed design requirement တွေရအောင် တွက်ကြည့်ပါမယ်။

 ✳️ Assume Design requirement 

-Target strength (f′c) :  28 MPa (at 28 days)

-Max. w/c ratio:  0.50

-Slump:  100 ± 25 mm

-Max aggregate size:  Assume 19 mm

-Air entrainment:  Assume non-air-entrained concrete

✳️ Assumed material property

-S.G of Cement: 3.15, Sand: 2.6, Aggregate: 2.7

-FM of Sand: 2.7

-Unit Weight of aggregate: 1600 Kg/m3

✳️ Step-1 Water content (from Table A1.5.3.3)

From Table A1.5.3.3 for non-air-entrained, slump 100 mm, 19 mm aggregate,

Water content = 205-Kg/m3

✳️ Step-2 Cement content (from W/C ratio)

Cement content = 205/0.5 = 410-Kg/m3

✳️ Step-3 Coarse Aggregate (SSD)

From ACI Table A1.5.3.6: for 19mm Aggregate, slump 100mm and FM of sand 2.7,

Volume of coarse aggregate = 0.63 m3 / m3 of concrete 

Unit Weight of coarse aggregate: 1600 Kg/m3, 

Mass of aggregate = Unit Weight x Volume = 1600 x 0.63 = 1008 Kg/m3

 

✳️ Step-4 Absolute Volume of ingredient

အပေါ်မှာတွက်ချက်ခဲ့တဲ့ Cement, water, coarse aggregate တွေဟာ Mass (Weight) အနေနဲ့ တွက် ယူထားပေမယ့် Concrete 1-m3 Volume ထဲမှာ ပါ၀င်နေတဲ့ ပမာဏ တွေဖြစ်ကြပါတယ်။ ဒါကြောင့် အဆိုပါ material များကို Volume ပြောင်းပေးရပါမည်။

-Cement 410-Kg/m3, S.G of cement: 3.15, Volume= 410 / (3.15 x 1000) = 0.13-m3 [from formula: Volume of material = Mass / (S.G x 1000)]

-Water 205-kg/m3, S.G of water: 1.0, Volume 0.205-m3

-Coarse aggregate 1008 Kg/m3, S.G of aggregate (oven dry) = 2.7, Volume = 1008 / (2.7 x 1000) = 0.373-m3

✳️ Step-5 Fine aggregate/sand (SSD)

Volume of sand = [concrete 1m3- cement V- Water V- Coarse aggregate V) = 1 - 0.13 - 0.205 - 0.373 = 0.292-m3

Mass of Sand= 0.292 x 2.6 x 1000 = 759 Kg/m3

✳️ Content of material per cubic meter (m3) of concrete (Mix Design)

✏️By Weight

-Cement: 410-Kg/m3

-Water: 205-kg/m3

-Aggregate: 1008-Kg/m3 (max: 19mm)

-Sand: 759-Kg/m3

Total Weight: 2382-Kg/m3

✏️By Volume

-Cement: 0.13-m3

-Water: 0.205-m3

-Aggregate: 0.373-m3

-Sand: 0.292-m3

Total Volume: 1-m3 of fresh Concrete

📝Note: FA/CA ratio (by weight) = 759 / 1008 = 0.75 (It should be in between 0.35 to 1. Lower ratio for harsh mix and higher ratio for higher workability and pumpable concrete)

Clarification အတွက် Air content, admixture volume များထည့်မတွက်ထားပါ။ moisture adjustment များ ထည့်မတွက်ထားပါ။ လက်တွေ့မှာတော့ အဆိုပါ အချက်တွေပါ ထည့်သွင်းစဥ်းစားတွက်ချက်ကြရပါသည်။

Concrete Mix Design နဲ့ ပတ်သက်တဲ့ အခြေခံအချက်များသာပြီး ဗဟုသုတရစေရန် အတွက်ရည်ရွယ်ပါတယ်။ 

ဆွေလှိုင်ဦး (မြို့ပြ ၂၀၀၄)

Fundamentals of Concrete Mix Design (Part 4)  

Concrete Mix Design Sample (ACI 211.1)  

We will now prepare a sample concrete mix design using the ACI method. Following the tables in ACI 211.1, we will calculate the assumed design requirements.  

Assumed Design Requirements  

- Target strength (f′c): 28 MPa (at 28 days)  

- Max. w/c ratio: 0.50  

- Slump: 100 ± 25 mm  

- Max aggregate size: 19 mm (assumed)  

- Air entrainment: Non-air-entrained concrete  

Assumed Material Properties  

- Specific Gravity (S.G):  

  - Cement: 3.15  

  - Sand: 2.6  

  - Coarse Aggregate: 2.7  

- Fineness Modulus (FM) of Sand: 2.7  

- Unit Weight of Coarse Aggregate: 1600 kg/m³  

Step 1: Water Content (from Table A1.5.3.3)  

For non-air-entrained concrete, slump = 100 mm, and 19 mm aggregate:  

Water content = 205 kg/m³  

Step 2: Cement Content (from w/c ratio)  

Cement content = Water content / w/c ratio = 205 / 0.5 = 410 kg/m³  

Step 3: Coarse Aggregate (SSD Condition)  

From ACI Table A1.5.3.6 (for 19 mm aggregate, slump = 100 mm, FM of sand = 2.7):  

- Volume of coarse aggregate = 0.63 m³ per m³ of concrete  

- Unit weight of coarse aggregate = 1600 kg/m³  

- Mass of coarse aggregate = 1600 × 0.63 = 1008 kg/m³  

Step 4: Absolute Volume of Ingredients  

The calculated quantities (cement, water, coarse aggregate) are in mass (weight), but we need their volumes in 1 m³ of concrete.  

- Cement (410 kg/m³, S.G = 3.15):  

  Volume = 410 / (3.15 × 1000) = 0.13 m³  

- Water (205 kg/m³, S.G = 1.0):  

  Volume = 205 / 1000 = 0.205 m³  

- Coarse Aggregate (1008 kg/m³, S.G = 2.7):  

  Volume = 1008 / (2.7 × 1000) = 0.373 m³  

Step 5: Fine Aggregate/Sand (SSD Condition)  

Volume of sand = 1 m³ – (Cement V + Water V + Coarse Aggregate V)  

= 1 – 0.13 – 0.205 – 0.373 = 0.292 m³  

Mass of sand = 0.292 × 2.6 × 1000 = 759 kg/m³  

Final Mix Design per m³ of Concrete  

By Weight:  

- Cement: 410 kg/m³  

- Water: 205 kg/m³  

- Coarse Aggregate (19 mm max): 1008 kg/m³  

- Sand: 759 kg/m³  

Total Weight: 2382 kg/m³  

By Volume:  

- Cement: 0.13 m³  

- Water: 0.205 m³  

- Coarse Aggregate: 0.373 m³  

- Sand: 0.292 m³  

Total Volume: 1 m³ (fresh concrete)  

Notes:  

- FA/CA Ratio (by weight) = 759 / 1008 = 0.75  

  (Should typically be between 0.35 to 1.0—lower for harsh mixes, higher for workable/pumpable concrete.)  

- This example does not include:  

  - Air content adjustments  

  - Admixture volumes  

  - Moisture corrections  

  (In practice, these factors must be considered.)  

This is a basic introduction to concrete mix design for educational purposes.