The tunnel to the shelter was some eight hundred and thirty meters long, with its entrance toward the center of the island. The tunnel entrance, too, had outlying bunkers to cover it, which bunkers could only be reached from culverts leading off from the tunnel.
* * *
'Who are they?' Carrera asked, still shouting over the jackhammers below.
'The 'Rebars,' ' Cheatham shouted back. 'The 'Rebar and Mold Detachment.' Concrete hasn't much tensile strength on its own. They put in the rebar lattice—reinforcing iron rods—that give tensile strength to the concrete.'
Cheatham pointed as a different crew, sweating, straining, grunting and cursing for every meter gained, as they rolled precast concrete culverts to the site and laid and joined them in the trench behind a bunker's hole.
'We use from twenty to seventy meters of culvert to join each bunker to either the central shelter or a tunnel. We mostly cut and cover those. See those old plastic soft drink bottles?'
Carrera, tired of shouting, nodded.
'They keep their shape and they don't degrade under environmental stress. We put them around the culverts to provide a bit of space for earth displaced by bombardment. It ain't perfect but we think it will help.'
* * *
Away from the central shelter, the BFW carpentry department (Bravo Maniple, 2nd Cohort) built—or rather, since the parts were manufactured at a central site near the cantonment area and then moved, rebuilt—the wooden interior mold to a fighting bunker. That was heavy plywood, mostly, with strong wooden beams at the corners and edges. Heavier logs formed a roof that would absorb spalling if the shelter took a direct hit on top from a bomb large enough to break pieces from the interior face of the concrete. A thick layer of synthetic rubber was glued to the interior of the plywood mold to help reduce the concussive effects of incoming high explosives.
A steel mold was erected around the rebar. It was perpendicular to the ground on the sides. Several other mold sections, which formed a dome when joined over the main construction, were set up nearby. The overall site engineer, in the corporation's military configuration he was a tribune, returned during the molding and rebaring phase to direct the placement of the flattish trapezoidal shapes that defined the firing ports so that they would cover the maximum possible terrain while providing the minimum possible target. The sometime captain had to slither through the rebar, snake-like, to get behind the trapezoidal mold in order to orient it just right.
The Rebars also installed the pipes that would allow grenades to be dropped from the inside of the design to the revetted ditch that would be left in front of it. They emplaced the double curved pipe that would provide an air vent—doubly curved with a drainage pipe that led outside to prevent inflammables being poured down it into the bunker. Fixtures for steel shutters were added in this phase of construction along with the pintle that would hold and guide the cradle for the bunker's eventual main weapon.
* * *
'Come on,' Cheatham shouted, 'they're ready to pour that one.'
That one, Carrera saw, was a major fighting bunker.
The molds were in place, covering the lattice of rebar that would reinforce the structure. A trough led to them from a cement truck just off of the road. At a signal from the engineer foreman (who also happened to be a reserve centurion; go figure) the truck driver wrenched a lever. Cement, good quality Portland with a partially coral aggregate and reinforcing aramid fibers for added tensile strength, began to flow down the trough, helped by engineers with paddles.
'We put in an additive,' Cheatham explained, in a somewhat softer voice now that they'd left the jackhammers behind. 'It helps the concrete flow.'
The first concrete filled the floor and sealed around the culvert that, along with the bunker, would later be covered by earth. The culvert led to another excavation, deeper and wider. The first truck was empty before the area defined by the molds was more than one sixth filled.
When the first truck had pulled out, empty, another pulled into position to dump its six cubic meters. Then came a third, fourth, and fifth through ninth. During the pour of the sixth, seventh, and eighth trucks the construction crew added sections of dome mold and threw in an assortment of shaped pieces of plastic, of an average dimension of two inches on a side.
'Good job, boys,' said the foreman of the crew. 'Back to the truck. We can fill three or four more before nightfall.'
* * *
'It'll be a couple of days,' Cheatham said, as he escorted Carrera back to his vehicle, 'but that bunker is now the responsibility of the 'Recovery' team. They'll wait until the concrete's set sufficiently for the molds to be taken down, then pass the molds on back to the 'Rebars.' The interior mold, the treated plywood, we leave in place.
'After that, a couple of days after, the 'General Labor Group' comes in to put more hollow plastic cubes and soda bottles around the sides and then fill the dirt back in over the bunker and the cubes and culvert. They also do the re-camouflaging with the foliage we stripped off in the beginning.'
'Remind me,' Carrera said, a look on his face composed half of wonder . . . and half of financial desperation, 'remind me of just how much concrete we are going to be using.'
'This fort will take seventy-two hundred cubic meters,' Cheatham answered, without hesitation. 'Some forts will take a bit less, others, somewhat more. More than ten times what goes into the forts is going into the entire program. If you want a big figure, that's one hundred and five thousand truckloads of concrete. If you want a little one, it's only going to equal a cube about one hundred and ten meters on a side.
'Of course, that's still about what went into the Maginot Line, six centuries ago, on Old Earth. And,' Cheatham added, 'we have some advantages over that system of fortifications. We can't be flanked.'
Chapter Ten
Along with all the other illusions and frauds of human existence, there have been and are the millennial philosophies, those reform movements who promise us a paradise in this life, if only we would X or Y or Z. There
