"How far along are you with this one, Sam?" Carrera asked.
The engineer shrugged, saying, "About a quarter done, though the thing won't really be ready until the concrete's had some time to cure.
"Come on down, let me show you how the boys work."
* * *
BFW had organized itself into several teams for the effort. The first, or 'survey,' team found and marked the site for the fort's bunkers, shelters, and tunnels according to the master plan. It also marked the direction in which the bunkers were to be able to fire. Following the survey team, an 'access' team made sure that the construction equipment and materials would be able to get close enough to the planned site.
Sometimes the access team needed to do nothing; trees in triple canopy jungle grew rather far apart. At other times the team had to cut a tree or a few trees, lay some steel planking, gravel or light asphalt, or build a trough from the nearest convenient point to the bunker site.
An excavation team did such digging as the bunkers, the shelters, and the culverts and tunnels that would lead to them required. Where needed they also put in temporary supplements to the main drainage system. The excavators were careful to preserve the top soil and any vegetation separately before digging deeper. There was no ecological motive in this; they simply wanted the soil and plant life for natural, self-replenishing camouflage.
Some excavators used heavy digging equipment. Other excavation was done by hand by some hundreds of healthy and strong criminal prisoners—politicals were not used on the works—serving sentences of less than fifteen years. These earned two days of 'good time' for every day of adequate performance. The work was hard but, since the food was rather better than a prison's mess, because a small stipend was paid, and because of the chance to live something closer to a normal life, convicted criminals tried very hard to get on the program. Another inducement, not much mentioned, was occasional access to a small brothel integral to the temporary prison camp. Female criminals—again not politicals—gained the same benefits as the male laborers for service in the brothel. As with the excavators, only volunteers were accepted for service in the brothel and health was an absolute requirement.
Looks were not but, then again, criminals didn't really deserve the best.
* * *
"We reached bedrock with this one," Cheatham explained in a loud voice, pointing into a hole. "We don't always."
Over the noise of the jackhammers scoring the bedrock to allow rock to displace in the event of a subsurface burst from a penetrating bomb, Carrera asked, shouting, "What if you can't reach bedrock?"
"In those cases," Cheatham answered, "the excavators bore anywhere from three to seven holes down to bedrock and set up concrete pylons to support the base of the bunker. Sometimes, the bunker has to be built on a sort of concrete 'raft' to prevent it sinking into the ground or being displaced by a near miss from a bomb."
Carrera nodded. "Ah, yes, Sitnikov mentioned the rafts to me once."
* * *
A substantial team of tunnelers, these from Balboa Exploratory Mining, a wholly owned subsidiary of Balboa Foundation and Wall (and also known as 4th Battalion (Heavy Construction), 70th Engineer Tercio) had dug space for the two hundred and forty man shelter inside of the hill the fort was intended to dominate. This was more than the strength of a normal infantry maniple but it was assumed that the fort might well be cut off and have to be self-sufficient for a period of time until relieved. It would be manned by a very overstrength company.
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."