Pavement shot blasting machines can prevent bridge deck cracks. Before waterproofing a bridge deck, the concrete surface must be pre-treated. This process is typically performed using a pavement shot blasting machine. After completion, if cracks develop on the bridge deck due to poor construction techniques or material quality, shot blasting equipment can often be used to assist in repair. This process is gentle on the concrete and, compared to milling machines, can prevent cracks and protect the bridge deck from severe mechanical impact. Let's look at the types of bridge deck crack damage.
1. Microcrack Stage (Initial Form)
Characteristics: Spot-like or short cracks, typically less than 0.2mm wide.
Forming Mechanism:
Insufficient low-temperature crack resistance of asphalt mixture (risk increases when penetration ≤ 50%)
Repeated stress caused by dynamic bridge loads (most likely to occur at vibration frequencies of 5-15Hz)
Water seepage accelerates freeze-thaw cycles (damage is significant when water absorption > 0.5%)
2. Linear Cracks (Development Form)
Spatial Distribution:
Longitudinal cracks: Mostly occur in the mid-span area of continuous beam bridges (deflections > L/500)
Transverse cracks: Common near the supports of simply supported beam bridges (shear stress concentration area)
Deterioration Mechanism:
The stress concentration factor at the crack tip can reach 2.5-3.0.
Annual growth rate: Approximately 1-3mm/year (under heavy traffic conditions)
3. Network Cracks (Compound Form)
Structural Characteristics:
Cracks spaced 20-50 cm apart, forming a grid.
Stripping is likely to occur at intersections (peel strength drops below 0.3 MPa).
Hazard Level:
Water permeability increases by over 300%.
Breaking distance increases by 15-20% (when friction coefficient is <0.45).
4. Cracking (Special Form)
Specific Cement Concrete Defects:
Surface Shrinkage: 3-5 mm deep, crack spacing 5-10 cm (caused by improper curing).
Alkali-Aggregate Reaction: Cracks are distributed radially (occur when ASR expansion ratio is >0.1%).
Warping: Maximum arching can reach 10-15 mm/m.
