Abstract: Vehicle arresting blocks of cellular concrete are usable to safely slow travel of an object and may be used to construct an aircraft arresting bed at the end of an airport runway. For such purposes, cellular concrete blocks must be fabricated to exhibit compressive gradient strengths of predetermined values to provide sufficient, but not excessive, deceleration forces on an object. Material uniformity characteristics must be met to avoid unacceptable drag force variations, so that arresting blocks desirably exhibit a predetermined compressive gradient strength (e.g., a 60/80 CGS) over a depth of penetration of 10 to 66 percent of block thickness. A 60/80 CGS will typically represent an average compressive strength of 70 pounds per square inch over such depth of penetration. Prior applications of cellular concrete typically involved meeting minimum strength values and the production methods did not meet uniformity or compressive gradient strength predictability as required for arresting blocks.

Abstract: An apparatus for controlling the rate of deceleration of a moving body. The apparatus has a cable or net for engaging a moving body and tape connected to the cable or net. The tape is wound onto a reel at the start of a deceleration and is unwindable from the reel during the deceleration so that unwinding the tape from the reel causes a corresponding rotation of the reel. A pump is operatively connected to the reel so that rotation of the reel causes pumping of a hydraulic fluid at a rate which increases as the rate of rotation of the reel increases. A control valve disposed across the discharge of the pump varies pressure drop across the control valve. A brake is provided for applying a braking force to the reel, and an actuator is provided for varying the braking force applied by the braking means in response to the pressure drop.