Sandbags
Sandbags are sacks made of burlap, polypropylene or other materials that is filled with sand or soil and used for such purposes as flood control, military fortification, shielding glass windows in war zones and ballast.
Advantages are that burlap and sand are inexpensive, and that the bags can be brought in empty and filled with local sand or soil.
Sandbags may be used during emergencies when rivers threaten to overflood, or a levee or dike is damaged. Sandbags are not always an effective measure in the event of flooding because water will eventually seep through the bags and finer materials, like clay, may leak out through the seam. After usage, dry sandbags can be stored for future use.
flood sandbags
The military uses sandbags for field fortifications, or as a temporary measure to protect civilian structures. The friction created by moving soil or sand grains and multiple tiny air gaps makes sandbags an efficient dissipator of explosive blast. As plain burlap sandbags deteriorate fairly quickly, sandbag structures that are meant to remain in place for a long time may be painted with a portland cement slurry to reduce the effects of rot and abrasion.
Cotton Ducking sandbags last considerably longer than burlap and are hence preferable for long-term use. However, the vast majority of sandbags used by modern militaries and for flood prevention are made of circular woven polypropylene. The easy availability to military personnel, size and construction of the bags has also led to the use of sandbags as makeshift hoods for prisoners of war.
Sandbags have been used since at least the late 1700s. Sandbags are also used in weight training either homemade or products like the neoprene SandBell from Hyper Wear.
There are alternatives to sandbags which can be used for light water diversion and ballast.
Also, check out other information on Poly Bags and Cellophane Bags.
Summary about sandbags. Source from Wikipedia
