Following Are The Formulas To Calculate How Much Concrete You Will Require For A Square Or Rectangular Shaped Pour:
L x W x T ÷ 12 = cubic feet of concrete
Number of bags of concrete needed:
CF ÷ 0.45 = number of 60 lb. bags
CF ÷ 0.6 = number of 80 lb. bags
Number of cubic yards of concrete needed:
CF ÷ 27 = cubic yards
L = Length in feet
W = Width in feet
T = Thickness in inches
CF = Cubic feet of concrete
Following Are The Formulas To Calculate How Much Concrete You Will Require For A Circle Tube Or Column Shaped Pour:
3.14 x r x r x H ÷ 1728 = cubic feet of concrete
Number of bags of concrete needed:
CF ÷ 0.45 = number of 60 lb. bags
CF ÷ 0.6 = number of 80 lb. bags
Number of cubic yards of concrete needed:
CF ÷ 27 = cubic yards
r = radius of the circle in inches
H = Height in inches
CF = Cubic feet of concrete
Following Are The Formulas To Calculate How Much Concrete You Will Require For A Circular Slab:
3.14 x r x r x T ÷ 12 = cubic feet of concrete
Number of bags of concrete needed:
CF ÷ 0.45 = number of 60 lb. bags
CF ÷ 0.6 = number of 80 lb. bags
Number of cubic yards of concrete needed:
CF ÷ 27 = cubic yards
r = radius of the circle in feet
T = Thickness in inches
CF = Cubic feet of concrete
What Does Psi And Mpa Mean When They’re Used To Describe A Concrete’s Strength
Psi means “Pounds per square inch”.
This is a measure of the concrete’s compressive strength or it’s ability to handle compression per square inch.
It’s also a measure of the concrete’s ability to carry a “load”.
MPa’s means Megapascals, this is how concrete strengths are labeled in the metric system.
It also refers to the concrete’s compressive strength and it’s ability to handle “loads” put upon it.
Should I Order Concrete By The Yard From A Ready Mix Company Or Just Use Bags
Larger jobs such as driveways are easier to complete when ordering concrete by the yard, rather than trying to mix bag after bag by hand. For smaller jobs, like a walkway, modest patio or footings, you should calculate the number of concrete bags instead.
Bagged concrete is ideal for:
- Pouring small slabs for sidewalks or patios
- Setting posts for fences or mailboxes
- Making repairs to foundation walls, walkways or steps
- Pouring small curbs, steps, or ramps
- Footings for decks, pergolas, walls and more
If you’re purchasing bagged concrete you may be able to have it delivered, but if it is only a few bags you’ll be responsible for transporting it yourself. You’ll also need additional equipment for mixing the concrete. A rented mixer can be very helpful, but a wheelbarrow works for just a few bags.
Ready mixed concrete by the yard is good for:
- Large patios, driveways, pool decks and more
- Foundation slabs for a house
- Parking lots or commercial sidewalks
If you’re planning to order concrete from a ready mix supplier, they’ll need to know how many yards of concrete to deliver. Many ready mix companies will have a minimum order of 1 yard, and will charge shortage fees when ordering partial batches. The average truck holds between 9 and 11 yards total. If your project requires more concrete, multiple trucks will be necessary.
These Are Actual Concrete Mix Ratios For 3000 3500 4000 And 4500 Psi Concrete
These concrete mix ratios for 3000, 3500, 4000, and 4500 psi concrete come from the ready mix concrete company I use to pour concrete floors, slabs, patios, pool decks, and stamped concrete.
I’m going to show you the actual batch plant ticket they give me when the concrete trucks show up on the job and we pour the concrete.
My name is Mike Day. I own Day’s Concrete Floors, Inc. My company pours concrete almost every day of the work week. We use the 4 mix designs shown above for most of our projects.
See me explain this page in the video below!
How Many 40lb 50lb 60lb And 80lb Bags Of Concrete Are In A Cubic Yard
How many 40lb, 50lb, 60lb, 80lb and 90lb bags of concrete are in a cubic yard | How many 60lb bags of pre mix concrete in 1 cubic yard | How many 80lb bags of pre mix concrete in 1 cubic yard | How many 90lb bags of pre mix concrete in 1 cubic yard | How many 40lb bags of pre mix concrete in 1 cubic yard | how many bags of concrete for a cubic yard | how many bags of concrete are in a cubic yard
Concrete ready mix made of blended mix of Portland cement, sand gravel and other approved ingredient, generally, dry ready mix concrete are available in different bag size and weight condition like 40lb bag, 60lb bag, 80lb bag 90lb bag and etc.
Weight of Ready mix concrete in dry condition is about 133 lbs per cubic foot, 3600 lbs per cubic yard, or 2136 kg per cubic meter. The weight of concrete is determined by its density, which can vary based on the amount of aggregate, water, and air in the mix.
In United States, based on Imperial measurement system, 1 cubic yard is unit of measurement of volume represented by 3 feet long by 3 feet wide by 3 feet depth , so 1 cubic yard is equal to 27 cubic feet.
How Many 40lb 60lb 80lb And 90lb Bags Of Concrete Are In A Cubic Yard
In United States, based on Imperial measurement system, 1 cubic yard is unit of measurement of volume represented by 3 feet long by 3 feet wide by 3 feet depth , so 1 cubic yard is equal to 27 cubic feet.
Weight of Ready mix concrete in dry condition is about 133 lbs per cubic foot, 3600 lbs per cubic yard, or 2136 kg per cubic meter. The weight of concrete is determined by its density, which can vary based on the amount of aggregate, water, and air in the mix.
In this regard, “how many bags of concrete are in a cubic yard”, according to imperial or US customary measurement system, generally there are 40 bags of 90lb, 45 bags of 80lb, 60 bags of 60lb, 72 bags of 50lb or 90 bags of 40lb of concrete you will need to make a cubic yard. Thus 40 bags of 90lb, 45 bags of 80lb, 60 bags of 60lb, 72 bags of 50lb or 90 bags of 40lb of concrete is a cubic yard of concrete.
One may ask, how many bags of concrete in a yard?”, generally you will need 40 bags of 90lb, 45 bags of 80lb, 60 bags of 60lb, 72 bags of 50lb or 90 bags of 40lb of concrete mix to make a cubic yard of concrete that will cover around 108 square feet area upto a standard depth of 3 inch for your slab and patio.
What’s The Difference Between 3000 Psi Concrete Vs 4000 Psi Concrete
The MAIN difference is in the amount of cement used. A cubic yard of concrete, whether it’s 3000 psi or 4000 psi, weighs about 4000 pounds .
But, there’s 511 pounds of cement used to make 1 yard of 3000 psi concrete and there’s 624 pounds of cement used to make 1 yard of 4000 psi concrete.
The ratio of cement to stone stays about the same but the ratio of cement to sand goes down with less sand being used as the strength of the concrete goes up.
In simple terms, MORE CEMENT PER YARD = HIGHER PSI CONCRETE
The same is true for 20MPa concrete VS 30MPa concrete.
How Do I Achieve These Strengths If I’m Mixing The Concrete By Hand
Just use the mixing ratios above as a guideline. However you’re measuring the cement, stone, and sand, just understand it takes a little more cement to achieve a stronger concrete mix.
If you’re mixing concrete by hand, there’s probably no way you’ll be able to tell if it’s 3000 or 4000 psi concrete.
Keep the water to a minimum, just use enough to make a “workable mixture”. Using too much water will weaken the mix and it’ll be more likely to crack.
DISCLAIMER: All the concrete mixing ratios above are from the Ready Mix Concrete Company I use to place and finish my concrete projects.
I only specialize in placing and finishing concrete flatwork. I don’t make, batch, design or sell concrete.
Use these concrete mixing ratios at your discretion. I only wrote this page to help you understand the differences in mixing ratios between 3000, 3500, 4000, and 4500 psi concrete.
Would you prefer to share this page with others by linking to it?
Hi, I am Mike Day, owner of Day’s Concrete Floors, Inc. in Maine, where I’ve been working with concrete for 40 years now, and this website is where I can share with you all the knowledge and wisdom I’ve gained from installing all kinds of decorative concrete, concrete floors, concrete overlays, stained concrete and also fixing cracked or spalled concrete.
What Equation Should I Use To Find Out How Much Concrete I Need
How to calculate concrete:
Here’s what the math looks like for a 10’ by 10’ concrete patio:
Essentially you are solving for volume and then converting to cubic yards. For concrete, the formula for volume is as follows: length x width x thickness.
To determine how many bags of concrete you will need, divide the total cubic yards needed by the yield.
Use the following yields per each bag size:
- 40 pound bag yields .011 cubic yards
- 60 pound bag yields .017 cubic yards
- 80 pound bag yields .022 cubic yards
Whats The Difference Between A Concrete Slab And A Cement Slab
What is the difference between cement and concrete? Although the terms cement and concrete often are used interchangeably, cement is actually an ingredient of concrete. Concrete is a mixture of aggregates and paste. The aggregates are sand and gravel or crushed stone; the paste is water and portland cement.
Calculating The Amount Of Concrete Needed For Footings
Footings will rarely follow the drawing exactly. In rocky soil the footings may collapse when big rocks are excavated
This was supposed to be a 12″*12″ footing, but note how the left side of the footing has collapsed. Calculate the true width.
The excavator may have dug too deep, or it may have rained and footings needed to be dug out deeper to reach firm soil. So it is important to check a variety of spots on your footing and get an average size. Then use the calculator to figure the amount of concrete needed.
House slabs on grade that are 8″ out of grade with a 4″ slab also have some of the footing above the grade too.
This 12″ x 12″ footing needs to be calculated 12″ x 16″ so the footing is figured to go above grade to reach the 4″ slab thickness.
How Do I Calculate How Much Concrete I Need For A Slab
To calculate the amount of concrete you need for a slab, you should find the cubic yardage of the area you will be filling. Just follow these steps:
Ready to start your Concrete Project?
What Is The Concrete Mix Ratio For 3000 Psi Concrete
The concrete batch plant ticket you see below is for an 8 yard load of concrete.
On the bottom of the ticket it shows you the actual weight of cement, sand, aggregate, and water. It also shows the air-entrainment and a water reducer .
Air-entrainment is used in climates that have freeze & thaw cycles to help keep the concrete from scaling.
Water reducer is used to help make the concrete mix more workable without adding water to the mix.
On the ticket you can see the actual weight of 8 yards of concrete:
1. Cement = 4086 pounds
2. Stone = 13,270 pounds
3. Sand = 11970 pounds
THIS GIVES YOU A BASIC 3000 PSI CONCRETE MIX RATIO OF:
- 1 PART CEMENT
Rounded off it’s basically a 1 : 3 : 3 mix ratio
If I break the weights down per yard of concrete it comes to:
1. Cement = 510.75 pounds
2. Stone = 1658.75 pounds
3. Sand = 1496.25 pounds
A sack or “bag” of cement weighs 94 pounds so this tells us a 3000 psi concrete mix is also equal to a 5.5 sack mix of concrete.
94 pounds x 5.5 bags of cement = 517 pounds
For more 1 on 1 help with concrete mixing ratios, join The Concrete Underground where I can help you with your specific questions through my private forum.
I have a lot of experience and knowledge with mixing ratios and I have access to many professionals in the business that may be able to help you with your specific needs.
What Is The Concrete Mix Ratio For 3500 Psi Concrete
The concrete ticket below shows a 3500 psi concrete mix for 10.5 yards of concrete. The ticket breaks down the weights of the amount of cement, stone, and sand used to make the 3500 psi concrete.
The actual weights used to make this 10.5 yard load were:
1. Cement = 5,805 pounds
3. Sand = 15, 440 pounds
THIS GIVES YOU A BASIC 3500 PSI CONCRETE MIX RATIO OF:
- 1 PART CEMENT
Rounded off it’s basically a : 1 : 3 : 2.5 mix ratio
If I break the weights down per cubic yard of concrete it comes to:
1. Cement = 553 pounds
2. Stone = 1630 pounds
3. Sand = 1470 pounds
There are 94 pounds of cement in a “sack or bag” of cement. That means 3500 psi concrete is called a 6 sack mix or 6 bag mix of concrete. .
Cool Things You Can Make By Mixing Your Own Concrete
- for your lawn or garden
For very small projects, such as setting a mailbox post or doingrepairs, you may want to purchase a packaged concrete mix. Such a mixcombines cement, sand, and gravel in the correct mixing ratios andrequires only the addition of water to create fresh concrete.
These concrete mixture ratios are designed for the concrete toreach full strength at or around 28 days old.
Curing the concrete can bedone by keeping it wet after the first day until the concrete is 7 daysold.
Curing is an important step to take for the concrete to achieve fullstrength by 28 days.
Watch my video talking about what concrete mixing ratios it takes to achieve 3000 psi, 3500 psi, 4000 psi, and 4500 psi concrete.
I also break down the equivalent 20mpa, 25mpa, 30mpa, and 35mpa concrete mixing ratios.
See the video HERE.
Calculating The Amount Of Concrete Needed For Slabs
Rule of thumb: add 1/4″ to the thickness of your slab for your slab concrete budget. This assumes you have the job evenly graded to the right depth, and the grade is well compacted.
If you check your grade and one spot is 4″, some spots are 4.5″ to 5″-the best solution for both the job quality and your concrete budget is to fix the grade.
Odd shapes: Transform odd shapes into rectangles and odd shapes are suddenly easy to figure.
Figure driveway 14′ x 20′ and your estimate will be good. Here is why: The driveway is 16′ at the top and 12′ at the bottom. Through the center the width averages 14′.
How Many 50 Lb Bags Of Concrete Are In A Cubic Yard
50lb bag of premixed cement, sand and gravel as concrete is around 0.375 cubic foot per bag , as we know there are 27 cubic feet in one cubic yard, so number of 50 lb bags of concrete are in a cubic yard = 27/0.375 = 72 bags,
In this regard, “how many 50 lb bags of concrete are in a cubic yard?”, generally you will need 72 bags of 50lb concrete mix to make a cubic yard of concrete that will cover around 108 square feet area upto a standard depth of 3 inch for your slab and patio. Thus there are 72 bags of 50lb concrete needed to make 1 cubic yard of concrete.
Deciding The Thickness Of Your Patios Concrete Slab
A patio’s best feature is that it has next to zero maintenance. Though you do need to put in a few fine touches here and there, you really don’t have to do much to keep up the appearance of your outdoor escapade.
This varies from one type to the next.
Three of the most commonly chosen patio types include the paver, stone and concrete slab patio. Among the three, the easiest to sustain are those made out of concrete. While they come in many forms, the concrete slab is the best option to go for when you are looking for a flat, smooth and stable patio that gives you thermal heating and the best flooring to work with.
Being the best option naturally has its drawbacks. While it may seem to be quite simple, constructing a Concrete Slab for your patio can be complicated in itself. Don’t even get me started on the concrete composition, placement and measurement to get the slab into place. On top of that, timing and proper setup of your concrete slab is essential for the stability of your patio floor. That said, let’s dig into all the details before you get started.
How Many 60lb Bags Of Concrete Are In A Cubic Yard
60lb bags of concrete mix in ideal for both structural and non structural application 2 inch thick or more, this is ready mix to use as concrete contains mix blended of Portland cement, sand, gravel and other approved ingredients.
60lb bag of premixed cement, sand and gravel as concrete is around 0.45 cubic foot per bag, as we know there are 27 cubic feet in one cubic yard, so number of 60 lb bags of concrete are in a cubic yard = 27/0.45 = 60 bags.
In this regard, “how many 60 lb bags of concrete are in a cubic yard?”, generally you will need 60 bags of 60lb concrete mix to make a cubic yard of concrete that will cover around 108 square feet area upto a standard depth of 3 inch for your slab and patio. Thus there are 60 bags of 60lb concrete needed to make 1 cubic yard of concrete.
How Many 80lb Bags Of Concrete Are In A Cubic Yard
80lb bags of concrete mix in ideal for both structural and non structural application 2 inch thick or more, it is ideal for sidewalks, curbs, steps, ramp, walkway and patio. This is ready mix to use as concrete contains mix blended of Portland cement, sand, gravel and other approved ingredients.
80lb bag of premixed cement, sand and gravel as concrete is around 0.60 cubic foot per bag, as we know there are 27 cubic feet in one cubic yard, so number of 80 lb bags of concrete are in a cubic yard = 27/0.60 = 45 bags.
In this regard, “how many 80lb bags of concrete in a yard?”, generally you will need 45 bags of 80 lb concrete mix to make a cubic yard of concrete that will cover around 108 square feet area upto a standard depth of 3 inch for your slab and patio. Thus there are 45 bags of 80lb concrete needed to make 1 cubic yard of concrete.
How Many 90lb Bags Of Concrete Are In A Cubic Yard
90lb bags of concrete mix in ideal for both structural and non structural application 2 inch thick or more, 90 lb bag of Concrete Mix can be used for building or repairing foundation walls, sidewalks, curbs, steps and ramps and for setting posts. This is ready mix to use as concrete contains mix blended of Portland cement, sand, gravel and other approved ingredients.
90lb bag of premixed cement, sand and gravel as concrete is around 0.676 cubic foot per bag, as we know there are 27 cubic feet in one cubic yard, so number of 90 lb bags of concrete are in a cubic yard = 27/0.676 = 40 bags.
Regarding this, “how many 90 lb bags of concrete in a yard?”, a 90 lb bag of concrete yields 0.025 cubic yard, as we know 1 yard concrete weighs around 3600 lb, so number of 90 lb bags of concrete in a yard = 3600/90 = 40 bags, so there are 40 bags of 90 lb concrete in a yard.
In this regard, “how many 90 lb bags of concrete in a yard?”, generally you will need 40 bags of 90lb concrete mix to make a cubic yard of concrete that will cover around 108 square feet area upto a standard depth of 3 inch for your slab and patio. Thus there are 40 bags of 90lb concrete needed to make 1 cubic yard of concrete.
How Many 40lb Bags Of Concrete Are In A Cubic Yard
40lb bags of concrete mix in ideal for both structural and non structural application 2 inch thick or more, 40 lb bag of Concrete Mix can be used for building or repairing foundation walls, sidewalks, curbs, steps and ramps and for setting posts. This is ready mix to use as concrete contains mix blended of Portland cement, sand, gravel and other approved ingredients.
40lb bag of premixed cement, sand and gravel as concrete is around 0.30 cubic foot per bag, as we know there are 27 cubic feet in one cubic yard, so number of 40 lb bags of concrete are in a cubic yard = 27/0.30 = 90 bags.
In this regard, “how many 40 lb bags of concrete are in a cubic yard?”, generally you will need 90 bags of 40lb concrete mix to make a cubic yard of concrete that will cover around 108 square feet area upto a standard depth of 3 inch for your slab and patio. Thus there are 90 bags of 40lb concrete needed to make 1 cubic yard of concrete.
How Do You Calculate A Smaller Concrete Mix Ratio
If you need less than 1 cubic yard of concrete you can mix your own on site either by hand, using the tools above, or by using an electric concrete mixer like the one in the link above.
To make smaller batches of concrete, use the sameproportions, but with smaller quantities, substituting buckets forcubic feet.
For any batch size, the most important thing is to keep theproportions of the ingredients the same. You can double or triple thebatch size simply by doubling or tripling the number of buckets of eachingredient you add to the mix.
Number Of Bags Of Concrete Needed For A 1010 Slab
Knowing how many bags of concrete mix you need before your pour cement is a crucial step to take before starting the whole process. Most concrete mixes are already prepared in specific bag sizes that you can then order from Amazon or other manufacturing websites. Ordering the right amount will save you money, time, and a headache.
To construct a 10×10 slab of concrete with a minimum depth of 4-inches, you will need the following number of bags depending on the weight of the mix:
Sure, there are calculators out there to help you figure this out, but this is an easy process you can do by yourself. In order to calculate how much concrete you need for any given concrete project, all you need is to know the cubic feet of the concrete slab you’re making, the cubic feet a bag of concrete yields, and a little bit of math.
What Is The Concrete Mix Ratio Of 25mpa Concrete
25 MPa concrete is equivalent to a 3500 psi concrete mix. So the mix ratio is the same as above:
- 1 Part Cement
Rounded off it’s basically a 1 : 2 : 2 concrete mix ratio
If I break the weights down per cubic yard of concrete, it comes to:
1. 702.5 pounds of cement
2. 1587 pounds of stone
3. 1217 pounds of sand
NOTE: This load of concrete only had 3/8″ stone in it. Some of the other ones had 3/4″ or a mixture of both 3/4″ and 3/8″.
This would be considered a 7.5 bag mix of concrete.
What’s The Difference Between Concrete & Cement
The words “concrete” and “cement” are often used interchangeably, however, they are two very different things. Concrete is a mixture of cement and other items, such as sand or gravel. Cement is an ingredient in concrete and is the “glue” that helps hold the mixture together. Once concrete hardens, it can be used to create stairs, sidewalks, landing pads, or other solid surfaces, as well as footers for decks.
How Many 60 Pound Bags Of Concrete Make A Yard
You will need 60 bags of concrete mix to make a cubic yard of concrete.
A 60 lb bag of concrete yields approximately .45 cubic feet
There’s 27 cubic feet of concrete in a yard. If you divide 27 by .45 it equals 60 bags of concrete.
How many square feet will a 60 lb bag of concrete do?
- @ 2″ thick a 60 lb bag of concrete will fill 2.7 sq. ft.
- @ 4″ thick a 60 lb bag of concrete will fill 1.35 sq. ft.
- @ 6″ thick a 60 lb bag of concrete will fill 0.90 sq. ft
How Many Square Feet Are In A Yard Of Concrete
The amount of square feet you will fill with a yard of concrete will depend on the thickness.
- @ 4″ thick a cubic yard of concrete will fill an area of 81 sq. ft.
- @ 5″ thick a cubic yard of concrete will fill an area of 65 sq. ft.
- @ 6″ thick a cubic yard of concrete will fill an area of 52 sq. ft.
FOR EXAMPLE: How many bags of concrete do I need for a 10′ x 10′ slab?
10 x 10 = 100 sq. ft.
- For a 4″ thick slab, 100 sq. ft. / 81 = 1.23 yards of concrete or 56 bags of concrete
- For a 5″ thick slab, 100 sq. ft. / 65 = 1.54 yards of concrete or 70 bags of concrete
- For a 6″ thick slab, 100 sq. ft. / 52 = 1.92 yards of concrete or 87 bags of concrete
For the calculations above, I rounded up to get an even number of bags.
How Do You Calculate Concrete For A Round Hole
They are 4 feet in height and 10 inches in width , or 4? x 10?.
You might be interested: How Long After Power Washing Can I Seal Concrete?
Concrete Patiowhat Type Of Mix: 4 Sack 5 Sack
27 FEET by 21 FEET by even 2″ thick is a LOT of concrete to be doing by hand.At the far more proper 4″ depth and allowance… you’re far closer to 8 yards.Any job using this much ‘crete should be getting it delivered.
Am taking estimates from local contractors. Apr 18, 2012Apr 18, 2012Apr 18, 2012Apr 18, 2012Apr 18, 2012Apr 19, 2012http://www.ce.memphis.edu/1112/notes/project_2/PCA_manual/Chap09.pdf
How Many 80 Lb Bags Of Concrete Are In A Yard
80bagcementbagyard80bags
The finished volume of an 80# bag of Sacrete or Quikrete is 0.6 cubic foot . There are 27 cubic feet in a cubic yard. Dividing 27 cubic feet by the volume of the bag will give you the number of bags you need.
Subsequently, question is, how many bags of concrete make a yard? # It takes approximately 5 Bags of Portland cement, 8 cubic ft of sand, and 20 cubic ft of gravel to make approximately 1 cubic yard of concrete.
Secondly, how many 60 pound bags of cement does it take to make a yard?
60 pound bag yields .017 cubic yards. 80 pound bag yields .022 cubic yards.
How many bags of concrete does it take to fill a tire?
Four to six bags of concrete depending on how big the tires are.
How Many Bags Of Cement And Ballast Do I Need
How Many Bags Of Cement And Ballast Do I Need? You will need 1 bag of cement for every 6 bags of ballast for a concrete mix suitable for driveways, paths, and patios. Change the ratio to 1:8 for concrete suitable for foundations.
Concrete is made up of a variety of ingredients. A primary component is a coarse aggregate, also known as “ballast.” This is a substance that is added to cement to help bind aggregate particles together.
The strength of the concrete is affected by the amount of ballast added. The strength of mixed concrete is usually determined by the application. 1 part cement to 5 parts ballast would be used to make high-strength concrete.
The following general rules are frequently used to make concrete of a specific hardness: For foundation-strength concrete, a 1:8 mix is ideal.
Seven 50 kg bags of cement can easily produce 1 cubic metre of concrete at 3500 psi . Patio slabs, footpaths, and steps can all benefit from this type of concrete.
For every ton of concrete, how many tons of ballast are required? 2.5 tons, possibly delivered on a small lorry, difficult to shovel out of 1 ton bags 2.7 tonnes of ballast is the answer There are 27 no. 25kg cement bags in 675kg of cement . To concrete a 5m x 3m area at 100mm thick, you’ll need 2.5 tons of ballast, which equals three one ton bags.