Transport Damage: Is the Problem on the Truck or in the Stack?
When blocks arrive at the construction site and are unloaded, edge chipping, stack tilting, or even partial collapse is discovered. The supplier's first reaction is usually to look for the logistics cause-poor road conditions, rough loading and unloading, or sudden braking by the driver. But when the damage rate is traced to its root, a considerable portion of the problems are not created during transport at all; they are already "designed into" the stack shape at the moment the blocks leave the palletizing station.
The industry has a common baseline for transport damage: the transport damage rate of blocks is typically around 2% as the normal range, and below 2% is considered an acceptable level. This figure may not look high, but it means that for every 1 million blocks delivered, 20,000 blocks have already lost their value before reaching the customer. And when stack shape control at the palletizing stage is inadequate, this proportion quickly breaks through the baseline.
The starting point of damage often lies in the way loads are transmitted between layers. If the blocks in the upper and lower layers do not form an effective interlocking arrangement during palletizing, the weight of the upper layers will concentrate on the weak edges of a few blocks in the bottom layer. Vibration and bumps during transport do not "create" damage; they merely expose the stress concentration points that already existed during palletizing. A stack that looks neat in a static state may begin to loosen from the inside after the first bump. This is precisely the significance of a stack pattern that uses interlocking placement supplemented by restraining layers: let the load be distributed evenly across the entire stack body, rather than concentrated on a few lines.
The verticality of the stack body is the second easily overlooked indicator. With manual palletizing or equipment with insufficient control precision, cumulative deviation often exists in the vertical direction-a few millimeters of deviation per layer, and over a dozen layers it becomes a visibly tilted stack. A tilted stack has an offset center of gravity during transport, and when turning or braking, inertial forces concentrate on the tilted side, multiplying the risk of collapse. An automatic palletizing system with sufficient precision can control the stack verticality error within ≤3 mm, keeping the stack body stable as a whole after long-distance transport and multiple loading and unloading cycles.
Packaging is the last line of defense, but the loopholes it can patch are limited. "Well"-shaped packaging combining horizontal and vertical straps, together with sufficient welding strength, can indeed reduce the transport damage rate from the higher levels of traditional methods to below 1%. But the role of the strapping is to "restrain displacement," not to "repair structure." If the stack itself is loosely arranged and there is no interlocking between layers, the straps can only bind a pile of loose blocks together to sway as a whole, and cannot prevent mutual friction and edge crushing between blocks.
The control of transport damage is essentially a quality gate that starts at the palletizing station. Palletizing precision, grouping logic, and stack stability determine whether the stack is "already at risk" when it leaves the factory, or whether it "has the structural integrity to withstand transport stress." Keeping the damage rate below the baseline does not rely on adding more cushioning materials to the truck, but on ensuring that every layer of blocks is in the correct position before the stack leaves the palletizer.
