Concrete is a key material in construction. To ensure the concrete you use is strong and durable, follow a few important steps. Making sure that the concrete mix ratio is optimal for your project is one of the first things you must look out for. We will discuss the essential parts of concrete mix ratios, how to calculate them, different types, etc. Let’s start with the basics.
Simply put, a concrete mix ratio is the specific proportion of materials that go into making concrete. The main ingredients in concrete are cement, sand, and aggregate (usually gravel or crushed stones). Concrete mix ratios are normally written in a sequence of numbers, like 1:2:4, where each number represents parts of cement, sand, and aggregate, respectively. In this case, 1:2:4 means one part cement, two parts sand, and four parts aggregate.
Concrete Mix Ratios define the strength, durability, and workability of the concrete you mix. If your concrete is weak, it will not hold up well and could eventually crack or collapse. Think of it like a perfect recipe for your favourite dish. Too much or too little of any of the ingredients, and it won’t have the traits you need.
While this whole process might sound complex to calculate, there is a simple way to do it.
You start by first determining what the project needs. Are you building a slab or a column? Do you want the right concrete mix ratio for the foundation? Each project has different requirements.
Maintain the Ratio Formula: In the case of the 1:2:4 ratio, if you are using 1 cup of cement, then you should use 2 cups of sand and 4 cups of aggregate. If you need a large batch, and you are using a bucket of cement, you should use 2 buckets of sand, and 4 buckets of aggregate.
Adjust the Quantity You Need: Make an estimate of the amount of concrete you will need for your mould or project area. You will need to multiply the proportions accordingly to get the right amount for your needs.
Be careful when you add the water. Add it slowly, mixing till the concrete reaches the right consistency.
There are several types of concrete mix ratios, depending upon the required strength and application. Here are some of the common ones and where you might use them
M5 Grade Concrete (1:5:10): The strength of this concrete mix ratio is slow and suitable for simple, non-structural appliances, like pathways and light-duty floors.
M7.5 Grade Concrete (1:4:8): It offers moderate strength and is commonly used in lighter construction like pavements and driveways
M10 Grade Concrete (1:3:6): It offers medium strength and is ideal for lighter projects including filling gaps and building non-load-bearing walls
M15 Grade Concrete (1:2:4): It has strong durability, making it an ideal concrete mix ratio for slabs, driveways, and some walls.
M20 Grade Concrete (1:1.5:3): It offers high strength and versatility enough for standard construction projects like columns, slabs, beams etc.
M25 Grade Concrete (1:1:2): It offers quite a high strength and is usually used in foundation construction and heavy structural loads. This is the ideal concrete mix ratio for columns and large slabs. Also, Read All You Need to Know About Concrete Mix Design
Mixing concrete is a hands-on process. It can be done by hand or with a mixer. Here is how you can do it.
Gather Your Materials. Make sure you have enough cement, sand, aggregate, water, and other tools you might need like a shovel or trowel.
Measure out each ingredient you need according to the ratio.
Mix the Dry Ingredients: Combine the cement, sand, and aggregate and mix them until they are thoroughly blended.
Add Water Slowly: Add less water you think you need. Mix till it reaches your ideal consistency.
Test the Consistency: The concrete should hold its shape if you scoop it with a trowel. It will crumble if it’s too wet and be runny if it’s too wet.
Pour and Level the Concrete: Pour the mix into your mould or form and use a levelling tool to smooth the surface.
Take the Weather into Account: If it’s hot outside, your concrete may dry faster. Look for slowing down the drying time by adding extra water or using additives.
Keep It Clean: Make sure all tools, surfaces, and materials are clean because dirt, debris, or old concrete can weaken the final result.
Use a Mixer for Large Projects: You can use hand mixing for small projects, but using a concrete mixer will save time and ensure a more consistent mix for larger projects.
Plan for the Job Site Conditions: If you’re working in an area where the ground is wet or muddy, you might have to think about using a higher concrete grade, as the wet ground can affect the strength and drying time.
If you are new, test a small batch first: If you’re new to mixing concrete, start with a small batch to make sure the ratio and consistency are right before committing to a larger amount.
