Concrete is a building material known for its marvellous strength and wide range of applications. Its usage worldwide (weight for weight) is twice that of wood, steel, plastic and aluminium combined. When mixed concrete hardens, it gives a stone-like finish that is extremely useful in construction. However, how is concrete produced, and how is the right mix achieved? In this article, we will enlighten you about the correct concrete mix ratio using ballast.
What Is Concrete Made Of ?
Mixed concrete is made up of basically two materials:
- Cement, the binder which holds other materials.
From rapid hardening cement to portland cement, natural or synthetic, cement is made of finely ground powder which hardens when it reacts with water. Water is crucial in the production of cement. Water-cement mix sets through a chemical process known as hydration.
Additives are added to give concrete other desired properties. Accelerators hasten the hydration process, and plasticisers improve the workability of concrete. Also, corrosion inhibitors minimise corrosion.
- Concrete ballast or aggregates, which provide the bulk, increases the strength of the concrete and improves its properties to suit its application.
Ballast for concrete comprises of coarse materials like sharp sand, gravel, and limestone. Concrete ballast or aggregates make up the bulk of the cement mix. Recycled materials such as air-cooled furnace slag or quenched molten slag are also used in ballast. The amount and particle sizes and distribution of concrete ballast added to a cement mix significantly affect the strength and the amount of cement used in the cement mix. Sometimes decorative stones such as river stones, quartzite and shattered glass are added for a more elegant finish known as an exposed finish.
More Ado About Concrete
High strength concrete has relatively high compressive strength. This strength is measured in megapascals (MPa) or pounds per square inch (psi). The compressive strength gives a measure of how well a material resists load due to compression. This high strength makes it suitable for roads, patio, bridges and other structural uses. Steel reinforcement is added to make it stronger. A wide range of concrete grade is used for different applications.
Low strength concrete has a strength of about 14MPa. It is often made by adding foam or using lightweight ballast mix. Concrete with over 35MPa in strength is regarded as commercial-grade concrete and is used in road works, foundations, support and structural beams. Concrete greatly exceeding 40 MPa is used in bridges and other heavy construction. The strongest of concrete grades used for super rigid structures generally exceed 100 MPa in strength.
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One of the most important factors in making concrete with your required strength is the cement to water ratio. Using less water makes the concrete stronger, and using excess water will make the concrete less workable. Also, using too much water leads to segregation of the sand and aggregate particles and cause microscopic pores in the concrete. This process is called bleeding, and it makes the concrete weaker than it should be.
Generally, your water to cement ratio should be between 0.35 and 0.6. If you need to mix concrete more than once for the same project, you should ensure that all batches of the concrete mix are consistent. More importantly, adjusting the cement to ballast ratio gives you varying concrete strength.
Ensure that the concrete is blended expertly to maintain its properties and for better workability. The aggregates and additives should be added after the water and cement have been mixed to achieve maximum strength.
Mixing The Right Amountof Ballast
For making a cubic metre of cement with 20 MPa strength, mix 320 kg of cement, 600 kg of sand with 1200 kg of aggregate. This can be easily scaled down to whatever amount you require. This concrete mix can be used on driveways and paths and other domestic purposes. The right amounts of ballast or sand-aggregate can also be expressed in simple ratios. So for the concrete mix mentioned above, your cement: sand: aggregate ratio should be 1:2:4 or ballast to cement ratio of 6 to 1.
For a low-grade concrete with 10MPa strength, the perfect ratio should be 1:3:6. For 30MPa concrete use 1:0.75:1.5. The cement to aggregate ratio should be increased to produce concrete with higher strength.
In Conclusion
Getting the right concrete mix ratio can be a tricky thing, but something else can be much more inconvenient, and that is transporting all the materials. You need professionals who will put you first at all times. At TJC Transport, we offer a wide range of aggregates which can be delivered to you. You can also choose to come to collect them. Contact us today!
FAQs
Mixing The Right Amount of Ballast
How much ballast do I need to mix concrete? ›
Mixing 1 part cement to 6 parts ballast creates concrete suitable for driveways, paths and patios, and increasing the ratio to 1:8 gives foundation-strength concrete. It is of course possible to add other materials to increase the strength of the concrete – these often include steel reinforcing bars (“rebar”).
How do you calculate how much ballast you need? ›
Determine how much ballast you need: As a general rule, you can assume about 1,750 kg to 1,800 kg of ballast per metre squared. So, for 2 cubic metres, you will need 3,500 kg of ballast. Ballast is relatively inexpensive so buying extra can be helpful.
What is the ratio of ballast to sand to cement? ›
Opting for 1-part cement and 5-part ballast will create a mix suitable for slabs and concrete panels. For the strongest concrete, such as that used within foundations, a 1-part cement to 8-part ballast mix will be used.
How much does one bag of ballast cover? ›
Quantity: 1000kg (1 tonne) bulk bag. Coverage: 1000kg of concrete ballast will typically cover 11m2 (11m x 1m) at a depth of 50mm.
How much ballast do I need for half a bag of cement? ›
About 12 shovels of ballast to half a bag. Lay bag of cement on floor, cut across the top/middle with a Stanley then lift it up quickly from the bottom so it folds in half. Cut through remaining paper then you can just whack half a bag straight in the mixer.
What is the mix ratio for concrete driveways? ›
A concrete mix of 1 part cement : 2 parts sand : 4 parts coarse aggregate should be used for a concrete slab. Concrete must be placed within half an hour of mixing.
What is the best ballast for concrete? ›
The best choice of all, however, is 20mm ballast, a mix of gravel and sand that is perfect for a concrete mix.
What is the formula for concrete mixing? ›
The ideal concrete mixing ratio for any concrete is 4:2:1, where 4 parts are crushed stones, 2 parts are sand, and 1 part is cement.
How do I know what size ballast I need? ›
How to pick a fluorescent ballast
- Step 1: Consider the lamps you're powering. ...
- Step 2: Consider how many lamps you're powering. ...
- Step 3: Consider what start type you need. ...
- Step 4: Consider the voltage powering your fixture. ...
- Step 5: Consider the dimensions of your ballast. ...
- Step 6: Consider the light output.
The amount of ballast force needed is equal to the weight it would take to counterbalance the buoyant force that is exerted on the station. The total ballast force is a combination of the weight of the soil column acting on the bottom flange of the tank, the weight of the tank, and the soil shear resistance.
What area does 1 ton of ballast cover? ›
Covers: A tonne bag of concrete ballast will normally cover 11m² (11m x 1m) at 50mm deep. Contains: Concrete ballast is a primary component in concrete and a mix of coarse sand, small pebbles and gravel.
What is the best cement sand ratio for concrete? ›
The standard mix, which has a ratio of 1:2:3 (cement: sand: aggregates) or 1:1.5:3.5, is the most popular kind of concrete mixture (cement: sand: gravel). This mix is malleable and hence can be used in multiple projects, such as foundations, walls, and slabs.
How much water do I add to ballast and cement? ›
W/c ratios of 0.45 to 0.6 are typically used . In case of high strength concrete , lower w/c ratios (0.23 to 0.35 )
What is the best sand for concrete mix? ›
Sharp sand is usually preferred over builders sand when making concrete because of its grittier consistency, however you can add a coarser aggregate to your builders sand if you don't have any sharp sand to make concrete.
How do I work out how much ballast I need? ›
To calculate the amount of ballast you will need find the weight of concrete required. To do this multiply the cubic meters by 1.5 which will give you the weight of the concrete required in metric tonnes.
How many bags of concrete do I need for a 10x10 slab? ›
How much concrete do I need for a 10x10 slab? The amount of concrete you need for a 10x10 slab depends on how thick it will be. So, for a 4-inch slab you'll need 1.24 cubic yards (56 80lb bags), but a 6-inch slab requires 1.85 yards (84 80lb bags).
What is the ratio of concrete base mix? ›
In terms of the ratio for concrete, it depends on what strength you are trying to achieve, but as a general guide a standard concrete mix would be 1 part cement to 2 parts sand to 4 parts aggregates. For foundations, a mix of 1 part cement to 3 parts sand to 6 parts aggregates can be used.
How much does 1 bag of ballast cover? ›
Coverage 1 x 25kg bag will cover 1metre x 1metre x 12. 5mm depth.
What is the ratio of ballast to concrete? ›
The right amounts of ballast or sand-aggregate can also be expressed in simple ratios. So for the concrete mix mentioned above, your cement: sand: aggregate ratio should be 1:2:4 or ballast to cement ratio of 6 to 1. For a low-grade concrete with 10MPa strength, the perfect ratio should be 1:3:6.
Concrete mix for shed base
A standard concrete mix ratio of 1 part cement to 5 parts ballast (aggregate and sand) is usually perfectly adequate for shed bases but you can add reinforcing fibres if you are housing anything particularly heavy. if you are unsure ask for advice from your ready-mixed concrete supplier.
What is the 1 2 3 rule for concrete? ›
Another "old rule of thumb" for mixing concrete is 1 cement : 2 sand : 3 gravel by volume. Mix the dry ingredients and slowly add water until the concrete is workable.
What is the strongest concrete mix for driveways? ›
Generally, the best concrete mix for your driveway should have a compressive strength of at least 3500 psi to 4000 psi, a cement-water ratio of around 0.50 to improve the concrete's longevity, and aggregates no larger than 1-inch in size with a slump of 4 to 5 inches.
What happens if I add sugar to concrete? ›
Sugar delays the setting time of cement by up to 1.33 hours at dosage level of 0.06% by weight of cement. No effect on workability, compaction by the use of sugar as admixture in concrete. Higher long-term compressive strength can be achieved in concrete by the use of sugar as admixture.
What is the ratio of ballast to cement for posts? ›
Making Dry mix concrete for fence posts.
20mm ballast, when mixed with cement, is also ideal for making dry-mix concrete which can be used to secure fence posts. Mix the ballast straight out of the bag with cement in a ratio of 7 ballast to 1 cement. Do not add any extra water. Mix well.
How much cement do I need for 3 ton of ballast? ›
3 tonne bags of ballast and 20 cement. 3:1 is too strong 5 ballast 1 cement and if you are to put a hot tub on it you should put at leat 1 layer of reinforcing mesh in. 3tonnes of concrete ballast and x12 cement.
What is the ratio for mixing cement? ›
The standard ratio for average mortar mix is 3:1 or 4:1 for bricklaying. If you are using a pointing mix, then you should have a ratio of 1:4 or 1:5 mortar to sand. As for concrete, it depends on the strength you need it to be at. Usually, it is good practice to mix concrete at 1:2 mix to materials.
How to mix ballast and cement by hand? ›
Carefully measure out about half the ballast (or sand and gravel) you are go mix - and dump it in the mixing area to form a cone shape. Use a shovel to form a crater in the middle of the heap, then measure out all the cement required and add this to the crater.
