You may be looking to lay some concrete to improve the look around your home or extend the usable space for your driveway or backyard space. You may be also considering a concrete contractor to complete your project or tackle it yourself. Whichever project you are looking to tackle you will need to know how to determine how much concrete you will need for tasks around the home including patio slabs, fence posts, pathways, and more. Calculators and tables are available online. However, such calculators are frequently associated with certain brands. Once you understand how to calculate concrete requirements, you can apply this knowledge to any type of concrete, any brand, and any project.
Measure the project area and determine the project depth
The very first thing you would need to do is to figure out how much space you need to fill with concrete. After that, you can figure out how many bags of dry concrete you may need to fill that space. Begin by measuring your project area, take down the length of one side then measure the length of the next perpendicular side. With those two measurements multiply them together to get the project area. In the case that your project area is in another shape other than a square or rectangle like a semi-circle or an intricate shape, measure the space in the shape of a square or rectangle and account for that area. You may have some excess concrete but having excess is better than having less than you need. After the area has been calculated, determine the project depth. This will dictate how deep the concrete will fill which will directly affect how much concrete is needed for your project.
Determining concrete volume
After calculating the area and depth of your project, determining the volume is your next step in knowing how much concrete you need. You take the area where you want to pour the concrete and the depth of that area, and from there you have the cubic feet of the concrete you need. We determine the amount of concrete required by multiplying the width by the length by the depth of the area where the concrete is to be poured. When measuring places that are not perfectly square and taking into account variables like grade and slope, this may get complicated. However, volume is always determined by the same formula, height by width by depth.
Choosing the ideal concrete mix
A concrete mix is made up of five basic components in varying proportions: cement, water, coarse aggregates, fine aggregates (i.e. sand), and air. Additional components, such as pozzolanic minerals and chemical admixtures, can be added to the mix to give it desired qualities. A ready-mix concrete design is a process of choosing the materials for a concrete mixture and determining their proportions. When creating a mix, keep in mind the needed strength, durability, and workability of the concrete for the project at hand.
Needless to say, all ready-mix companies attempt to identify the optimal amounts of these materials in order to maximize their concrete mixes and provide strength, durability, workability, and other desirable attributes. It is critical to optimize concrete to ensure the lowest possible cost while keeping the maximum possible strength of your mixture. This is far from simple since each addition or subtraction to the concrete mix requires changes to the components, making the process extremely difficult and sometimes inefficient. Concrete suppliers can offer a great amount of customization of mixes, where each mix can be custom tailored to every project type. The main characteristics of concrete mixtures are customized through PSI, slump, color, and texture.
Keep in mind the PSI of the concrete
PSI is an acronym for Pounds per Square Inch, which is a unit of measurement that is used to determine how much pressure a material can bear before failing. Your tires on your vehicle or bicycle have a PSI rating and you may find it in basketball or football as well. When an object exceeds its PSI limit they give in the pressure and break or explode. In relation to concrete, this implies that a specific mix can sustain a given amount of pressure before failing, breaking, or cracking. Aside from having the right amount of concrete to fill the area of your project you also want to ensure you have concrete that is durable and can withstand the weight of whatever will be passing or resting on your concrete surface. Measuring the PSI of a concrete mix is not something you can do at home as it usually takes the testing more than a month to determine. However, with the right supplier and professional concrete contractor, you can rest assured that the mix used will fit your desired project.
Concrete slump for different projects
A characteristic that can be overlooked when deciding how much concrete you need for your project is slump. Concrete slump is a measurement specific to the concrete industry that measures the consistency or workability of a substance such as concrete.
A slump test can be used to obtain that measurement. A simple slump test using a specific cone and tamper may be done on-site. You could most likely do one at home if your project is somewhere around your residence. Pour the mixed concrete into the cone, tamp it down slightly, and then remove the cone.
The slump is measured from the top of the cone to the top of the concrete. If it completely collapses, then it is a “collapse” slump. If some of it collapsed and some of it stood up, this is referred to as a “shear” slump. If the entire body stood up and retained its form, this is referred to as a “true” slump. You measure the “shear” droop from the top of the cone to the bottom of where the concrete fell.
Very dry mixes with slumps of 0 – 1 inch are commonly used in road construction, whereas poor workability mixes with slumps of about .25 inch – 1.5 inch are commonly used for foundations with little reinforcement. Slump 2-3.5-inch mixtures are commonly used for regular reinforced concrete poured with vibration. In selecting the right amount of concrete for the project, choosing a mix with the proper amount of sump is also important. It allows you to preview what your concrete will be like before it sets, allowing you to make adjustments to the mix to create a better product with more favorable consistency.
The dry weight of concrete is always displayed prominently on the face of the bag. However, it is not what you require. You must determine how much concrete is generated once it has been combined with water. You will approximately need 133.33 pounds of dry concrete mix to fill 1 cubic foot. You can take the total cubic footage once you have calculated the total volume of the project. Once you have determined how many pounds of dry concrete you require the next step is to determine how many bags to purchase. Simply multiply the total weight required by the weight of each bag to get the total amount of bags required. Now, if this may seem overwhelming or the project you are looking to complete is quite large, or have little experience working with concrete, speak with a professional concrete contractor.