Types, technical specifications, and a guide to selecting the appropriate excavator class for demolition and aggregate recycling on construction sites
The hydraulic crusher for excavators is one of the attachments that has the greatest impact on the profitability of a demolition site: it allows concrete, bricks, asphalt, and natural stone to be crushed on-site into recyclable aggregate, eliminating or drastically reducing transportation and landfill disposal costs.
Choosing the wrong crusher—one that is too small, too heavy, or has hydraulic requirements that are incompatible with the available excavator—results in lost productivity and additional costs. This guide explains the available types, the technical specifications to check, and how to properly match the crusher to the machine.
What is a hydraulic crusher for excavators, and how does it work?
The excavator jaw crusher attachment is a piece of equipment that replaces the bucket and uses the machine’s hydraulic power to drive two opposing jaws: one fixed and one movable. The material is fed into the feed opening, crushed by compression, and discharged in a size controlled by adjusting the discharge opening.
Unlike a hydraulic hammer, which strikes the material, the crusher compresses it between its jaws: this makes it ideal for producing recycled aggregate with a uniform particle size, which is more useful on construction sites and more easily marketable as a secondary raw material under Ministerial Decree 69/2018.
Types of jaw crushers for excavators
There are two main configurations on the market, each designed to meet different operational needs.
| Feature | Movable-jaw crusher | Fixed-jaw crusher |
|---|---|---|
| How it works | Both jaws move alternately | One fixed jaw, one movable jaw with eccentric motion |
| Crushing force | Distributed on a continuous cycle | Focused on eccentric movement |
| Suitable materials | Reinforced concrete, granite, basalt | Mixed demolition, unreinforced concrete |
| Output size | More uniform | Higher cycle speed on medium-weight material |
| Maintenance | More complex | More comfortable on the field |
| Excavator class | 12 tons and up | Also available for 6–10-ton excavators |
Technical specifications to consider before purchasing
Feed opening size
The feed opening (width × height) determines the maximum size of the input material. For the demolition of reinforced concrete structures, an inlet of at least 600 × 400 mm is recommended to allow for the feeding of medium-sized blocks without the need for pre-crushing. Larger inlets increase productivity but require larger excavators.
Discharge opening and output size
The discharge opening is adjustable and determines the particle size of the output material. For the production of recycled aggregate intended for road subbases, the optimal opening is generally between 40 and 80 mm. Smaller openings require more passes and reduce hourly throughput; larger openings produce less uniform material.
Hydraulic flow rate and required pressure
The crusher must be compatible with the excavator’s auxiliary circuit. Always verify the required flow rate (liters/min) and operating pressure (bar) against the machine’s actual specifications. Crushers for 20-ton excavators typically require flow rates of 120–180 l/min at 250–350 bar. Insufficient flow reduces crushing force; excessive pressure can damage the seals.
Weight and excavator class
The weight of the crusher is the most critical factor in making a choice: an accessory that is too heavy reduces the machine’s stability, accelerates joint wear, and can cause the boom’s rated load to be exceeded. As a general rule, the crusher should not exceed 6–8% of the excavator’s operating weight.
| Excavator class | Recommended weight for the crusher | Recommended minimum opening | Approximate hydraulic flow |
|---|---|---|---|
| 6–10 tons | 400–700 kg | 400 × 250 mm | 60–100 L/min |
| 10–20 tons | 700–1,400 kg | 550 × 350 mm | 100–160 L/min |
| 20–35 tons | 1,400–2,500 kg | 700 × 450 mm | 150–220 L/min |
| 35–50 tons | 2,500–4,000 kg | 900 × 550 mm | 200–280 L/min |
Table 1 — Recommended crusher/excavator class combinations. Values may vary depending on the manufacturer and specific model.
When to use the crusher: main operating scenarios
The hydraulic crusher for excavators is not a one-size-fits-all tool: it has ideal operating conditions, and there are situations where other attachments are more suitable.
| Use case | Recommended crusher | Why |
|---|---|---|
| Demolition of concrete foundations and footings | Movable jaws, wide mouth | High compressive strength on solid blocks; produces recyclable aggregate directly in the pit |
| Recycling of construction demolition debris | Fixed jaw, medium size | Optimal cycle speed on unreinforced concrete; uniform aggregate size for the subbase |
| Crushing of asphalt and bituminous concrete | Fixed jaw with wear-resistant liners | A tough but not hard material; special coatings extend the life of the jaws |
| Recycling of natural stone (excavations, quarries) | Movable jaws, very wide mouth | High-hardness abrasive material; requires high-manganese steel jaws |
| Urban construction sites with limited space | Mini crusher for 6–10-ton excavators | Compact design; operates in tight spaces without having to move materials off-site |
Table 2 — Operating scenarios and recommended crushers for each.
Economic and environmental benefits of on-site recycling
The most immediate benefit of a hydraulic crusher for excavators is the reduction in the volume of waste sent to landfills. By crushing concrete on-site, you obtain aggregate that—if processed in accordance with the requirements of Ministerial Decree 69/2018 (End of Waste)—can be reused directly as a subbase or sold as recycled aggregate.
Estimated savings on a typical construction site (demolition of 500 m³ of reinforced concrete):
- Landfill disposal cost (without crushing): €18,000 – €25,000
- Cost of disposal, including on-site crushing and recycling: €2,000 – €4,000
- Estimated savings: €14,000 – €21,000, excluding the cost of renting or depreciating the crusher
Source: Average market estimates. Actual figures may vary depending on the distance from the landfill and local pricing.
In addition to direct savings on disposal costs, the recycled aggregate produced has its own market value: the costs of purchasing virgin materials for subgrades and embankments are reduced or eliminated, resulting in a twofold economic benefit for the construction site.
CMB crushers for demolition and recycling
CMB Attachments manufactures jaw crushers for excavators compatible with machines ranging from Class 6 up to over 50 tons. The construction, featuring high-manganese steel for the jaws and Hardox for the structural components, ensures long service life even in the most abrasive applications, with 100% testing prior to delivery.
Frequently Asked Questions About Hydraulic Breakers for Excavators
What is the difference between a hydraulic crusher and a hydraulic hammer?
The hydraulic hammer strikes the material using a high-frequency pneumatic piston and is ideal for the targeted demolition of compact structures (rock, thick reinforced concrete). The jaw crusher compresses the material to break it into fragments of controlled size, and is ideal for reducing the volume of large quantities of demolition material. The two attachments are complementary: the hammer is often used for initial demolition, while the crusher is used to reduce the resulting aggregate.
Can the crusher process concrete with rebar?
Yes, movable-jaw crushers are designed to process reinforced concrete as well. The metal reinforcement is stripped and compressed between the jaws; however, the jaws must be made of high-manganese (Mn) steel, and the operator must periodically monitor wear. In the presence of particularly heavy rebar, it is recommended to combine the crusher with a Hydraulic Shear for the preliminary cutting of longer bars.
How much material can a crusher produce in an hour?
The hourly throughput depends on the crusher class, the feed size of the aggregate, and the hardness of the material. Under standard conditions (unreinforced concrete, input size 300–500 mm), a 20-ton excavator-mounted crusher produces between 40 and 80 tons of crushed aggregate per hour. For harder materials or larger input sizes, the throughput is reduced by 20–40%.
Do the jaws wear out quickly? How are they replaced?
Jaw wear depends heavily on the abrasiveness of the material: on standard concrete, they last an average of 500–1,000 hours; on basalt or granite, this can be reduced to 200–400 hours. CMB models feature reversible jaws (which can be flipped to use the unworn side) and are easily removable using standard tools, reducing on-site replacement time to 1–2 hours.
Looking for the right crusher for your excavator? CMB’s technical team can help you choose the model best suited to your excavator size and specific application. Request a personalized assessment or explore CMB’s Demolition line.