The mix ratios for concrete are typically expressed in terms of the proportions of cement, sand, and coarse aggregates. In the case of C20 concrete, the “C” stands for compressive strength, and “20” denotes a characteristic compressive strength of 20 megapascals (MPa) or 20 N/mm2.

Concrete is a blended mix of Portland cement, sand, aggregate, water with approve ingredient. The ready mix concrete can be used for building or repairing foundation walls, fence post, sidewalks, curbs, steps and ramps and for setting posts and others concrete structure like, footing, slab, beam and columns.

The compressive strength of concrete is typically measured in megapascals (MPa), N/mm2 or Psi (pounds per square inch). The strength depends on factors like mix design, curing, and quality of materials. Common strengths range from 20 MPa for low-strength applications to over 60 MPa for high-performance concrete.

In general, the compressive strength of C15 concrete is approximately 15 Mpa (or 2175 Psi), 20 Mpa ( or 2900 Psi) for C20 concrete, 25 Mpa ( or 3625 Psi) for C25 concrete, 30 Mpa ( or 4350 Psi) for C30 concrete, 35 Mpa ( or 5075 Psi) for C35 concrete, and 40 Mpa ( or 5800 Psi) for C40 concrete,

**Here are approximate mix ratios for different concrete grades:**

- The mix ratio for C10 concrete is typically 1:4:8, which means 1 part cement, 4 parts fine aggregate (sand), and 4 parts coarse aggregate (gravel or crushed stone).
- The mix ratio for C15 concrete is typically 1:3:6, which means 1 part cement, 3 parts fine aggregate (sand), and 6 parts coarse aggregate (gravel or crushed stone).
- The mix ratio for C20 concrete is typically 1:2:4, which means 1 part cement, 2 parts fine aggregate (sand), and 4 parts coarse aggregate (gravel or crushed stone).
- The mix ratio for C25 concrete is typically 1:2:3, which means 1 part cement, 2 parts fine aggregate (sand), and 3 parts coarse aggregate (gravel or crushed stone).
- The mix ratio for C30 concrete is typically 1:1.5:3, which means 1 part cement, 1.5 parts fine aggregate (sand), and 3 parts coarse aggregate (gravel or crushed stone).
- The mix ratio for C35 concrete is typically 1:1:2, which means 1 part cement, 1 parts fine aggregate (sand), and 2 parts coarse aggregate (gravel or crushed stone).
- The mix ratio for C40 concrete is typically 1:1:1.5, which means 1 part cement, 1 parts fine aggregate (sand), and 1.5 parts coarse aggregate (gravel or crushed stone).

**How much sand, cement and stone required for 1m3 concrete**

In general, 225kg of cement, 785 kg of sand and 1090kg of 20mm stone are required for 1 cubic meter of C15 concrete. This grade of concrete are used for footings for small walls and floor slab.

Roughly, 255kg of cement, 780 kg of sand and 1080kg of 20mm stone are required for 1 cubic meter of C20 concrete. This grade of concrete are used for single story foundations and internal floor slab.

Normally, 285kg of cement, 775 kg of sand and 1070kg of 20mm stone are required for 1 cubic meter of C25 concrete. This grade of concrete are used for foundation, mass concrete and trench fills.

In general, 330kg of cement, 760 kg of sand and 1050kg of 20mm stone are required for 1 cubic meter of C30 concrete. This grade of concrete are used for driveways, path, garage base, and structural RCC.

Roughly, 365kg of cement, 750 kg of sand and 1030kg of 20mm stone are required for 1 cubic meter of C35 concrete. This grade of concrete are used for external slab heavy duty application, and structural rcc.

Typically, 395kg of cement, 730 kg of sand and 1010kg of 20mm stone are required for 1 cubic meter of C40 concrete. This grade of concrete are used for external rcc floors, beams and columns.

**Here’s are table for the mix ratios for C20, C25, C30, C35, and C40 concrete and quantity of cement, sand and aggregate required for 1 cubic meter of concrete:**

SL.no | Concrete grade | Mix ratio | Cement quantity | Sand quantity | 20 mm stone quantity |

1 | C15 | 1:3:6 | 225 kg | 785 kg | 1090 kg |

2 | C20 | 1:2:4 | 255 kg | 780 kg | 1080 kg |

3 | C25 | 1:2:3 | 285 kg | 775 kg | 1070 kg |

4 | C30 | 1:1.5:3 | 330 kg | 760 kg | 1050 kg |

5 | C35 | 1:1:2 | 365 kg | 750 kg | 1030 kg |

6 | C40 | 1:1:1.5 | 395 kg | 730 kg | 1010 kg |

**Conclusions:**

The mix ratio for C20 concrete is typically 1:2:4, while the mix ratio for C25 concrete is typically 1:2:3. Likewise, the mix ratio for C30 concrete is typically 1:1.5:3, while the mix ratio for C35 concrete is typically 1:1:2. In addition, the mix ratio for C40 concrete is typically 1:1:1.5.