Construction Machinery, Earthwork and Foundation Techniques

Concrete Vibration Techniques and Frequencies

Frequencies:

• Low (1500-3000 rpm): Mobilize dry aggregates.
• Medium (3000-6000 rpm): Mobilize fine aggregates.
• High (12000 rpm): Affects mortar with little energy.

Classifications:

• Externals: Adapted to formwork or molds with vibrating rules (-amplitude, +frequency).
• Internals: Internal motor in the needle (40 mm diameter, electric high frequency and pneumatic converter -> few failures) or external motor in the needle (eccentric masses -> frequency multipliers by pinion and pendulum -> horizontal bearings).

Vibrators:

• Internal: Engine, hose, and needle.
• Frequencies: Massive 500-6000 rpm, 12000-20000 rpm for edification.

Needle Diameters in Edification:

• Normal: 38-40 mm
• 20 mm
• Solid

Action Radius and Execution:

Max radius 48-60 cm. The sink gets the 1st bar equal to the needle length in 1 minute. Internal vibrator rules: vibrate without touching the casing vertically, keep 1.5 pinx distance of effect radius, 5-10 seconds per pinx, do not leave holes, progress pinx laterally to level, layers under 50 cm, do not forge another tier until 1 day of vibration, and move vibrator to get the same slow speed.

End of VIBRATED: Up to the superior phase until the 1st fine liquid layer of mortar appears (leached or drained).

Defects in Vibrating:

• Lack of vibration: Air bubbles, gravel nests.
• Surface cavities: Entrained air pinned to the formwork.
• Loss of mortar: Due to poor fitting of formwork names, seat plastic cracking, or concrete mixing issues. Avoided by proper revibration.
• Color changes: Due to uneven vibration or formwork oil issues.
• Surface deformations: Excess power of the vibrator and critical crib vibration.

Excavations and Earthworks

Excavations:

• Open cast: Clearing the terrain, dismantling, trench (excavation below ground where length predominates), well, emptying, and trenching.
• Underground excavations: Tunnels, mines, and galleries.
• Underwater excavations: Require depletions under the phreatic level and are tested using pits.

Open Excavation Process:

1. Geotechnical information and setting out.
2. Clearing and cleaning.
3. Dismantling (if necessary).
4. Emptying.
5. Trenches (under 1.2 m might not require shoring).
6. Wells (with shoring or shielding).
7. Trenches.
8. Transversal cuts.

Backfilling:

Stone fill or earth fill. Backfill jobs: 1) Prepare seating layer, 2) Spreading (layers of 40-60 cm and compaction under 1/3 of layers), 3) Compaction with vibrators, 4) Leveling (coronation layer with finishing +-2 cm with motorgraders), 5) Moisture control (drying or watering). Complementary jobs: depletions, shoring, service lines, signaling, collective protections.

Terrain Classification:

• Rock (soft, hard, very hard), loose soils (light, ordinary, very dense).
• Regular (pick and shovel), transition (intermediate with ripper), rippable (requires ripper), and very hard (with explosives).

Emptied Methods Without Prior Structure:

1. Vertical cut (excavation and structure).
2. Cuts in slopes (definitive slope, slope and backfill, slope and benches).

Emptied Methods With Prior Structure:

1. Walls prior to containment structure (ditch, containment wall, and excavation).
2. Diaphragm walls (wall and excavation).
3. Simultaneous execution (initial excavation, wall part 1, anchors 1, excavation 2, partial wall 2, anchor 2).

Heavy Earthmoving Machinery

Bulldozers

On wheels (medium 60 hp and large 8t) and crawler tracks (optimal range 20-30m, regular up to 80-100m, pressure on soil 0.35-0.4 kg/cm²). Safety cabs (ROPS and FOPS). Blade types: U-blade (large capacity), semi-U, and angle blade. Ripper types: radial (1 pin) and parallelogram. Power ranges 70-770 hp, weights 7000-98000 kg. Movements include tilt and pitch. Speeds: excavation 2.5-3 km/h, return 7-10 km/h. Slope climbable up to 30%. Uses: hydraulic works, mountain roads, spreading earth fills.

Loaders (Bull)

Wheel (majority) and crawler types. Actions: load, dig, reverse, transport, discharge. Compositions include engine, frame, mechanisms, chassis. Speeds: loaded crawler 3 km/h, wheels 4-5 km/h; empty crawler 6 km/h, wheels 10-11 km/h. Working cycle: push, break, lift, transport, discharge. Bucket capacity 1.5 - 5.4 m³.

Backhoes

Used for ditches, dismantling, emptying. Types: fixed or mobile superstructure, wheeled or tracked. Range: 100+ hp, operational weight 20-100t. Bucket types: SAE, trench, cleaning, trapezoidal, bivalve.

Dumpers and Trucks

Dump trucks (2-3 axles, 13-20t), dumpers (26-38t), and off-road dumpers (up to 75t).

Piles and Foundation Techniques

Classification: In-situ or prefabricated. Material: wood, metal, reinforced concrete, prestressed.

Installation Mode: Displacement (avoids cave-ins, improves ground) or extraction (requires land evacuation).

Load Transmission: End-bearing piles or floating piles.

Prefabricated Pile Diameters: 22.5, 27.5, 35, 42.5 cm. In-situ: 35, 45 cm.

Execution Order: 1) Site setting out, 2) Cleaning, 3) Boring, 4) Reinforcement placement, 5) Concreting, 6) Pile caps and ties, 7) Head trimming.

Common Diameters: 35, 45, 55, 65, 80, 100 cm.

Diaphragm Walls (Slurry Walls)

Development: 1) Emptying, 2) Plane creation, 3) Digging guide walls, 4) Setting out, 5) Excavation (using slurry or dry methods with clamshell buckets or hydrofraise), 6) Tube placement, 7) Reinforcement cage introduction, 8) Concreting with tremie pipe, 9) Joint extraction, 10) Building the first tie beam.

Types: Continuous (plastic, prefabricated, sheet piles), modular, special (drains, sound insulation).

Drill Rigs and Micropiles

Wagon Drills: Depth 10-30m, hydraulic pressure. Used for service connections, anchor walls, micropiles, rehabilitations.

Micropiles: Used in difficult party walls, small buildings, traction elements. Process: 1) Drilling, 2) Insertion of casing and reinforcement, 3) Low-pressure sheath grout injection, 4) High-pressure final injection.

Graders and Compactors

Motorgraders: Used for leveling and spreading excavated layers. Power 140-275 cv. Frequent passes: leveling (3 passes), finishing (6 passes).

Compactors:

• Static: Roller (towed or self-propelled), pneumatic, mixed.
• Vibrating: Mechanical, manual.
• Dynamic: Manual rammers, automatic rammers, free-fall heavy tampers.

Cutting and Finishing Equipment

Cutting Machinery: Compound miter saws, table saws (230/400V, 4-8 hp), radial disc cutters, manual ceramic cutters.

Finishing Machinery:

• Trowels: Rotary or horizontal (3.7-8 kw).
• Floor Polishers: Stone 60 (roughing), 100 (smoothing), 120 (cleaning and polishing).
• Scarifiers: For surface leveling and removing old layers.