We normally keep a water-to-cement ratio of 0.35-0.50. Remember that the aforementioned numbers may vary depending on the moisture content of the sand and aggregate. For 1 cubic meter of M20 grade concrete, 8 bags of cement are required. 1 cu.m of M20 grade concrete requires 672 kilogram of sand. 1 cu.m of M20 grade concrete requires 1326 kg of 20mm aggregate. The total weight of the mixture is therefore 1 ton 10 kilograms.
The amount of cement needed depends on the type of cement used. Ordinary portland cement will set up to a strength of about 30 MPa (4500 psi), while high-performance cements can set up to 60-80 MPa (8,600-11,200 psi). However, these high-strength cements are more expensive and less available than ordinary portland cement.
In general, it takes about 25% more cement to get M20 grade concrete compared to standard concrete. This is because 20% less water is used when making M20 grade concrete and this increases the risk of dry mixes. Also, more coarse aggregates are required for M20 grade concrete which increases its cost.
M20 grade concrete should be mixed by hand or using a mixer truck with a mixing blade. Use a plastic shovel to add water to the cement mix to ensure even distribution.
The concrete must then be placed in a smooth layer and allowed to cure for at least 24 hours before being moved or loaded.
1 cubic meter of M20 grade concrete requires 1260 kg of 20mm aggregate. For comparison, 725 kg of gravel works well too.
The amount of aggregate required depends on the type of concrete you are making and the type of sand or gravel used. The standard recommendation is to use 20 percent of the total volume of concrete as aggregate. This means that 80 percent of the concrete should be void of aggregate to achieve maximum strength.
As a rule of thumb, one needs about 2-4 times more aggregate than the specified quantity of cement because some of it will get lost during mixing and hardening of the concrete.
Aggregate is used to provide stability when casting concrete. It can be as small as 0.5 mm if desired but larger particles are easier to find and handle. Concrete requires a certain amount of water to mix and this also removes some of the oxygen that would otherwise break down the cement paste so the mixture has to be mixed with air in order to cure properly.
Cement is the main ingredient in concrete and it determines its final strength. Cements come in the form of powder or rock and depending on how they are made they range from very expensive to very cheap.
M20 concrete has a volumetric mix ratio of 1:1.5:3, which means that 1 part cement, 1.5 parts sand, and 3 parts aggregate are required in volume to make M20 grade concrete. Volume Ratio of Concrete Mix
| Concrete Grade | Mix Ratio (Cement : Sand : Aggregate) | Compressive Strength |
|---|---|---|
| M15 | 1:2:4 | 15 N/mm2 |
| M20 | 1:1.5:3 | 20 N/mm2 |
1 cubic metre of M25 concrete requires -36 cft (0.77 m3, 1194 kg) of aggregate. 1 cubic metre of M25 concrete requires 11 bags (0.385 m3, 554 kgs) of cement, 18 cubic feet (0.385 m3, 6244 kgs) of sand, and 36 cubic feet (0.77 m3, 1194 kgs) of aggregate. The total weight of a cubic metre of M25 concrete is 0.98 tonnes.
The density of M25 concrete is 2700 kg/m3. The strength of M25 concrete reaches its maximum value in 28 days and then decreases until it reaches its minimum value after one year, at which time it needs to be replaced.
The volume of concrete that must be mixed to make a single cubic metre varies depending on the type of mix used. For example, a common household mix requires only 2 cups (473 ml) of water per 2 cups (473 ml) of dry cement, while a super-strength mix may require as much as 20 cups (473 ml) of water per 2 cups (473 ml) of dry cement.
In general, though, about 10 litres (26 fl oz/2 cups) of water are required per 2 cups (473 ml) of dry cement. To determine how many bags of dry material you will need, simply multiply the number of cubic metres by the density of your concrete.
The needed weight of cement is calculated by multiplying the volume of cement by the bulk density of cement. The bulk density of commonly used cement types (both PPC and OPC) is 1440 kg/cu.m. As a result, 8 bags of cement are needed to make one cubic meter of M20 grade concrete.
The maximum load capacity of a standard truck trailer is 22 tons. Thus, if you need to transport fresh concrete, it should be done in no more than two 20-foot loads or four 10-foot loads. If necessary, you can divide the total amount of cement into smaller batches so that they will fit into one trailer.
As with any other building material, the price of cement increases as the quality gets higher. Ordinary Portland Cement, or OPQC, is the lowest quality cement and is most commonly found at home improvement stores. It is suitable for use in parking lot surfaces, driveways, and similar applications where its color isn't important. It's also very affordable - around $15 per barrel at my local store. Higher quality cements include Type I and Type II. Type I has a bright white color and is suitable for painting your concrete surface before adding decorative items. Type II has several colors available and is best used for making decorative concrete designs or patterns. It's also more expensive - about $35 per barrel.
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