Guide to Cement and Aggregates Factors per Concrete Class Mixture

Handy guide on factors to multiply per cubic on different concrete class mixtures. Just multiply each factor to the total volume (in cubic meter) and you’ll get the needed amount of cement (40Kg/bag), sand (cu.m.) and gravel (cu.m.).

Class C (2,000 psi)
Cement 5.634 Bags
Sand 0.4794 cu.m.
Gravel 0.898 cu.m.
Class B (2,500 psi)
Cement 7.399 Bags
Sand 0.486 cu.m.
Gravel 0.8856 cu.m.
Class A (3,500 psi)
Cement 8.799 Bags
Sand 0.5724 cu.m.
Gravel 0.856 cu.m.
Class AA (4,000 psi)
Cement 11.729 Bags
Sand 0.475 cu.m.
Gravel 0.8344 cu.m.

The following factors were already added an average wastage add-ons of around 5% to 8%. This numbers should help average Filipinos to know draft amount of materials needed for minor concreting works.

To see all the material prices we have posted click here.

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15 thoughts on “Guide to Cement and Aggregates Factors per Concrete Class Mixture”

  1. Why is there a difference in formula? example class AA (1:1.5:3) Fajardo, Tagayun and yours. How did you came up with that multiplier? Correct me if I’m wrong, my elementary math understands ratio of 1:1.5:3 means 1 part cement in cbm : 1.5 part sand in cbm and 3 parts of gravel in cbm. 1 bag of 40 kg cement is 0.02cbm, right? How do we decide which one is correct? Thanks in advance.

    Reply
    • Hi John, these factors came from our previous company’s in-situ data which has been passed on to engineers. Yes, those ratio you stated should be correct. In fact, one of our workmate tried to measure how many bags of cement are there in one cubic meter using an improvised 1mx1m box. He came up with 0.0267cbm. We believe factors like how compact the cement is in the box matters. Several factors play with the overall strength of the concrete (aggregate’s quality, w/c ratio, curing etc.). If in the end each [or any of the three guides] came up with the required strength after 28 days, then, that’s the one you should follow. Thank you!

      Reply
  2. wastage factor of 5%-8% is rather high. the accepted norm (based on dpwh bidding documents) is 3% maximum only. however, if the preparation of concrete is not strictly monitored, then the 5%-8% wastage factor is acceptable. but then again, the owner should be vigilant when it comes to materials usage; oherwise . . .

    Reply
    • Hi Engr. Reginaldo, yes po. We considered low to average skilled workers on this, that is why. Salamat po sa remarks 🙂

      Reply
      • for 21Mpa (3000psi; assuming 1.00 cu.m. volume), it is normally as follows:
        cement (40kg bag) = 9.23 bags
        sand = 0.52 cu.m.
        gravel 3/4″ = 0.49 cu.m.
        gravel 3/8″ = 0.34 cu.m.
        admixture (superplasticizer G2) = 2.952 lit
        water = approx 170-208 liters

  3. I’m not very familiar with the classes of concrete but am I reading it correctly that A is 3ksi, B is 2.5ksi (lower than Class A), C is 3ksi and D is 3.5ksi?

    Reply

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