Construction material mixing system

A system for preparing a construction material mixture, the system comprising:

• a container including a generally flexible body, the flexible body having an interior for holding construction material mixture components for preparing the construction material mixture, the flexible body having an interior surface at least partially bounding the interior, the flexible body comprising a liquid impervious material constructed to prevent passage of the construction material mixture components through the flexible body, the flexible body having a mouth sized for receiving construction material mixture components into the interior and for dispensing the construction material mixture from the interior, the flexible body having a base section including a bottom portion opposite the mouth, the flexible body having an intermediate section between the base section and the mouth, the interior having a longitudinal axis extending from the mouth to the bottom portion,
• the flexible body being configurable in a loading configuration in which the mouth is open, the interior surface at least partially bounds the interior, and the interior has a shape and a first volume for receiving the construction material mixture components, the flexible body being sufficiently robust to maintain the mouth open and substantially maintain said shape of the interior when in the loading configuration with the flexible body at rest and the interior empty, the flexible body being sufficiently resilient to substantially regain said shape of the interior from at least one distorted shape of the interior if the flexible body is partially collapsed to the at least one distorted shape when the interior is empty,
• the flexible body being configurable in a collapsed configuration in which the interior has a second volume less than the first volume for forcing the construction material mixture out of the mouth to dispense the construction material mixture, the flexible body in the collapsed configuration having the base section collapsed toward the longitudinal axis and the intermediate section collapsed toward the longitudinal axis to decrease the interior to the second volume,
• the flexible body being configurable in an everted configuration in which the interior surface is exposed outside the mouth, the flexible body being sufficiently flexible to permit movement of the interior surface through the mouth to evert the flexible body to the everted configuration, and the flexible body being sufficiently flexible to permit movement of the interior surface back through the mouth to revert the flexible body.