A standard concrete truck typically holds between 9 and 11 cubic yards of concrete, though capacities can vary. This guide will delve into the specifics of concrete truck capacities and help you determine how much concrete a truck holds for your project.
Image Source: silo-pros.com
Deciphering Concrete Truck Capacity
When you’re planning a construction project that requires concrete, one of the most fundamental questions is: “How many yards of concrete can a truck carry?” This isn’t a one-size-fits-all answer, as several factors influence the concrete truck capacity. The most common units used in the industry are cubic yards, and knowing this is crucial for ordering the right amount of material.
The Standard Concrete Mixer Truck Size
The standard concrete truck volume is generally around 9 to 11 cubic yards. These are the trucks you’ll most frequently see on roads, delivering concrete for driveways, patios, small foundations, and various commercial applications. They are designed for efficiency and maneuverability, making them suitable for a wide range of job sites.
What Determines How Much Concrete a Truck Holds?
Several elements play a role in the concrete truck load size. It’s not just about the physical size of the drum.
Drum Volume vs. Actual Payload
- Drum Volume: The actual volume of the rotating drum is larger than the amount of concrete it can legally and practically carry.
- Legal Weight Limits: Trucks have strict weight restrictions based on road regulations and axle load limits. Overloading a truck is illegal and dangerous.
- Mix Design: Different concrete mixes have varying densities. A heavier mix will reduce the total volume that can be carried within legal weight limits.
- Slump: The slump of the concrete (how easily it flows) can also slightly affect how much can be loaded.
Types of Concrete Trucks and Their Capacities
While the 9-11 cubic yard range is common, there are variations.
Rear Discharge Trucks
These are the most prevalent type. They typically have a truck mixer capacity of:
- 9 Cubic Yards: A very common size, offering a good balance of capacity and maneuverability.
- 10 Cubic Yards: Slightly larger, providing a bit more material per trip.
- 11 Cubic Yards: Often the maximum capacity for standard rear discharge trucks, pushing the limits of legal weight and operational efficiency.
Front Discharge Trucks
Front discharge trucks offer a different loading and unloading mechanism. They are often preferred for tighter job sites or where precise placement is needed. Their capacities are similar, usually ranging from 9 to 10 cubic yards. The advantage here is the ability for the driver to control the chute from the cab, reducing the need for additional personnel.
Volumetric Concrete Trucks
These are a distinct category. A volumetric concrete truck doesn’t carry pre-mixed concrete. Instead, it carries the raw ingredients: cement, aggregates, water, and admixtures. The concrete is mixed on-site, in precise quantities, as needed.
- Flexibility: This offers incredible flexibility, as you can mix only what you need, minimizing waste.
- On-Demand Mixing: If you need more concrete than a standard truck can carry, or if your pour is spread over a long period, a volumetric truck can be the solution.
- Capacity: The “capacity” of a volumetric truck is less about a fixed volume of concrete and more about the total amount of raw materials it carries and its mixing rate. They can often produce 8-12 cubic yards of concrete per hour, and some larger units can produce even more. The key is that they can mix continuously as long as they have materials.
How Much Concrete Per Load?
The question of “how much concrete per load” directly relates to the concrete truck load size. For a standard rear discharge mixer, you can expect 9 to 11 cubic yards to be the typical load. If you need more than that for a single pour, you’ll need to coordinate multiple truck deliveries.
Calculating Your Concrete Needs: More Than Just Truck Size
Knowing how much concrete a truck holds is essential, but it’s only part of the equation. You need to accurately estimate the volume of your project.
Measuring Your Project for Concrete
This involves calculating the volume of the space you need to fill with concrete. The general formula is:
Volume = Length × Width × Depth
Make sure all measurements are in the same units, and then convert to cubic yards.
Converting Units to Cubic Yards
- Inches to Feet: Divide the measurement in inches by 12.
- Feet to Cubic Feet: Multiply length (ft) × width (ft) × depth (ft).
- Cubic Feet to Cubic Yards: Divide the total cubic feet by 27 (since there are 3 feet in a yard, and 3 × 3 × 3 = 27 cubic feet in 1 cubic yard).
Example:
Let’s say you need to pour a patio that is:
* Length: 20 feet
* Width: 15 feet
* Depth: 4 inches (which is 4/12 = 0.333 feet)
Calculation:
Volume in cubic feet = 20 ft × 15 ft × 0.333 ft = 100 cubic feet
Volume in cubic yards = 100 cubic feet / 27 = 3.7 cubic yards
Accounting for Waste and Overages
It’s always wise to order slightly more concrete than your exact calculation. A common recommendation is to add 5-10% for waste, spillage, uneven subgrade, and form bowing.
Continuing the Example:
If you need 3.7 cubic yards, adding 10% for overage:
3.7 cubic yards × 1.10 = 4.07 cubic yards
In this case, you would likely order 4.5 cubic yards to be safe, ensuring you have enough and allowing for the possibility of a truck delivering a standard increment.
Ordering Concrete: Working with Ready-Mix Suppliers
Ready-mix concrete suppliers usually work with standard delivery increments. You can’t typically order exactly 3.7 cubic yards. You’ll usually order in half-yard or full-yard increments.
Common Ordering Increments
- 4 cubic yards
- 4.5 cubic yards
- 5 cubic yards
- …and so on, up to the truck’s maximum capacity.
If your calculation, including overage, comes to 4.07 cubic yards, you would order 4.5 cubic yards. If it came to 9.2 cubic yards, you’d likely order 9.5 or 10 cubic yards, depending on the supplier’s increments and your comfort level with the overage.
Factors Affecting Concrete Delivery and Truck Size
Beyond the basic capacity, several other factors influence the delivery process and the choice of truck.
Job Site Accessibility
The size and accessibility of your job site are critical.
- Tight Spaces: If your job site is in a confined urban area or has narrow access roads, a smaller truck might be necessary. While a 10-yard truck might have the concrete truck capacity, it might not be able to reach the pour location.
- Bridge Load Limits: Some older bridges may have weight restrictions that could limit the size of concrete trucks allowed to cross them.
- Maneuverability: Even if a truck can reach the site, it needs space to maneuver into position to discharge the concrete. Front discharge trucks are often favored for their maneuverability.
The Role of Admixtures
Admixtures are chemicals added to concrete to modify its properties.
- Water Reducers: Can allow for less water, leading to a stronger mix, but might slightly impact the volume a truck can carry if weight is the limiting factor.
- Air Entrainers: Improve freeze-thaw resistance but can slightly reduce density.
- Retarders/Accelerators: Affect setting time and can influence the mix’s flowability.
These admixtures generally don’t drastically change the cubic yards concrete truck can legally carry, but they are part of the overall mix design that a supplier considers.
Truck Mixer Capacity Specifications
Manufacturers build trucks with different drum sizes and chassis configurations.
- Drum Size: The physical size of the steel drum is the primary determinant of its maximum potential volume.
- Chassis Strength: The truck’s chassis, suspension, and axles must be strong enough to handle the weight of the concrete and the drum.
- State and Local Regulations: As mentioned, weight limits vary significantly by region. A truck with an 11-cubic-yard drum might only be legally allowed to carry 9 cubic yards in certain areas due to weight restrictions.
Beyond Standard Trucks: Specialized Concrete Delivery
While the standard mixer truck is the workhorse, other options exist for specific needs.
Conveyor Belt Trucks
Some trucks are equipped with conveyor belts that can extend the reach of the concrete pour.
- Reach: These belts can typically reach 60-70 feet, allowing concrete to be placed over obstacles or in difficult-to-access areas without chutes.
- Capacity: The underlying concrete delivery truck volume is still the same (9-11 cubic yards), but the conveyor adds placement versatility.
Boom Trucks (Concrete Pumps)
Concrete pumps are not trucks that mix concrete; they are separate pieces of equipment, often mounted on a truck chassis.
- Function: They receive concrete from a standard ready-mix truck and pump it through a pipeline to the desired location.
- Reach: Booms can reach significant heights and distances, making them ideal for high-rise buildings, bridge decks, or large foundations where direct truck access is impossible.
- Volume: The truck supplying the pump still carries its standard truck mixer capacity. The pump’s capacity is measured in cubic yards per hour.
Frequently Asked Questions About Concrete Truck Loads
Here are some common queries related to how much concrete a truck carries.
Q: Can I order less than a full truckload?
A: Typically, no. Ready-mix suppliers usually have a minimum order quantity, often around 1-2 cubic yards. If you need less than what a standard truck can carry, you might be charged a “short load” fee. It’s best to discuss your project size with the supplier.
Q: What happens if I order too much concrete?
A: If you have leftover concrete, you’ll be charged for it. This is why accurate measurement and adding a reasonable overage percentage are crucial. Some suppliers might have a policy for taking back a small amount of unused concrete, but this is rare and usually involves significant fees.
Q: What is the maximum concrete a truck can hold?
A: The maximum concrete truck capacity for a standard rear-discharge truck is typically 11 cubic yards. However, legal weight limits might restrict the actual amount carried to 9 or 10 cubic yards in many areas. Volumetric trucks can produce more over time but are not limited by a single pre-mixed load.
Q: How does the slump affect how much concrete a truck holds?
A: While the primary limit is weight, a very high slump (very wet) mix can sometimes be slightly more challenging to control during discharge, potentially leading to minor spillage. However, the difference in total volume carried due to slump alone is usually not significant compared to weight restrictions.
Q: What does “cubic yards concrete truck” refer to?
A: This phrase refers to the volumetric measurement of concrete that a concrete mixer truck is designed to carry. It’s the standard unit of measure for concrete volume in North America.
Q: Is a volumetric concrete truck the same as a standard mixer?
A: No. A standard mixer carries pre-mixed concrete. A volumetric concrete truck carries raw materials and mixes the concrete on-site as needed. This offers more flexibility but requires different logistical considerations.
Q: How much concrete per load should I plan for my project?
A: This depends entirely on your project’s size. For small projects like a patio, 4-5 cubic yards might be sufficient. For larger foundations or slabs, you might need 10-20 cubic yards or more, requiring multiple truck deliveries. Always calculate your project’s volume and add an overage.
By carefully calculating your needs, considering the concrete truck capacity, and communicating effectively with your ready-mix supplier, you can ensure you get the right amount of concrete delivered for your project, efficiently and without unnecessary cost.