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Walk-Behind Concrete Saw

A walk-behind concrete saw — flat saw, slab saw — cuts slabs, pavement and roadways with a diamond blade on a wheeled, depth-controlled carriage the operator guides from behind. It is the machine for joint sawing, utility cuts and demolition sawing at grade.

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Models

Commonly 14–30 in

Blade capacity

Brands

Cat classes

Pick a size class — capacity and reach differ across the range.

How it works

The engine drives the blade shaft through belts while a raise-lower control sets cut depth against a gauge; the operator tracks a chalk or string line with a guide pointer, either pushing the saw or letting self-propelled drive hold pace. Cutting runs wet on most work — water fed to both blade faces cools the diamond rim and suppresses slurry-bound dust — with depth taken in staged passes on deep cuts rather than forced in one. Blade speed is matched to blade diameter for correct rim velocity.

Types & variants

Push flat saw: Operator-propelled saw at the light end of the weight spectrum for joints and shallow utility cuts.
Self-propelled flat saw: Transmission-driven carriage holds constant feed rate on deep or long production cuts.
Electric flat saw: Motor-driven version for interior slab cutting where engine exhaust is prohibited.
Heavy sawing machine: High-power unit for full-depth roadway and runway cutting.

Key specifications

Specification	Typical range	What it means
Blade capacity	Commonly 14–30 in	Largest blade the guard and spindle accept, which fixes maximum achievable depth.
Depth of cut	Typically to about 12 in	Matched to slab or pavement thickness; full-depth cuts at the top end take staged passes.
Operating weight	137–2132 kg across models	Heavier saws track straighter and absorb vibration but need ramps and equipment to move.
Fuel capacity	20 gal on listed models	Sets run time between refuels on long production cutting.
Engine power	0.2–74.3 hp across models	Power scales with blade size to maintain cutting force in deep or hard material.

How the industry sizes it

Walk-behind concrete saws are sized by blade diameter against required depth of cut, since a blade cuts to roughly a third of its diameter. Machines under 20 in blade capacity handle slab openings and control joints to about 7 in deep. Self-propelled mid-size units in the 20–30 in range take road cuts and full-depth slab removal to about 12 in. Large self-propelled flat saws above 30 in capacity perform full-depth highway and bridge-deck cutting.

Applications

Sawing control joints in slabs and pavement
Cutting existing slabs for repair and removal
Utility trench cuts in asphalt and concrete
Sizing sections before demolition
Sidewalk, curb and driveway cutting
Full-depth roadway and runway cuts

Safety & operation

Wet cutting is the primary silica control for flat sawing; dry cutting without dust collection on concrete violates the specified OSHA Table 1 methods for walk-behind saws.
Blades must be rated for the saw's spindle speed and inspected before mounting; a damaged diamond blade can shed segments at speed.
Utility strikes are a defining flat-saw risk — buried electrical, gas and communication lines are located and marked before any pavement cut.
Gas saws cutting indoors require ventilation or an electric machine; slurry control keeps walking surfaces and adjacent traffic areas safe.

Standards & certifications

OSHA · 29 CFR 1926.1153 Table 1: Specified silica controls for walk-behind saws — water delivery to the blade or equivalent dust capture.
CSDA · Best Practices: Concrete Sawing & Drilling Association practice documents for flat sawing operations.

Frequently asked

How deep can a walk-behind saw cut?

Depth is governed by blade capacity — a blade reaches roughly a third of its diameter. Machines under 20 in blade capacity cut to about 7 in deep; 20–30 in mid-size units reach about 12 in; and large flat saws above 30 in handle full-depth highway cuts.

What separates push saws from self-propelled models?

Push saws are lighter and operator-propelled, suited to joints and shallow cuts; self-propelled units use transmission drive to hold constant feed rate on deep or long production work.

Why does saw weight matter?

Mass holds the blade in the cut and tracks a straighter line in deep or reinforced concrete — models span 137–2132 kg, with the heavy end needing ramps and equipment for transport.

Is water required when flat sawing?

Wet cutting is the default: it is the specified silica control for walk-behind saws and controls diamond blade temperature; electric saws with vacuum systems cover interior dry-cut cases.

Compare popular models

Find by spec →

Normalised to the same units. A dash means the figure was not published.

Model	Engine power	Operating weight
Husqvarna FS 400 LV	12 hp	220 lb (100 kg)
Multiquip ST61230 / ST61460	15 hp	302 lb (137 kg)
Multiquip ST1 / ST1F	0 hp	8.8 lb (4 kg)
Multiquip ST3020B1	2 hp	-
Multiquip ST4125G	10 hp	-
Multiquip ST-70	80 hp	4,700 lb (2,132 kg)