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Method Statement for the Construction of Monolithic Strip Foundations and Basement Walls

This method statement regulates the comprehensive processes for constructing monolithic reinforced concrete strip foundations and basement walls. The document is adapted for international application and includes specifications for reinforcement, modular formwork assembly, concrete placement, and detailed winter concreting protocols at sub-zero temperatures.
6 sections 12 figures

Materials

  • Heavy concrete mix, classes C20/25 – C25/30
  • Reinforcement meshes and bars for spatial cages
  • Plastic or fiber-reinforced concrete spacers for concrete cover
  • Annealed steel tie wire
  • Emulsion release agent for formwork panels
  • Anti-frost admixtures: chloride salts (up to 2%), potash, sodium nitrite (up to 5%)
  • Plasticizing admixtures (lignosulfonates, naphthenate soap, or equivalents)
  • Thermal and vapor insulation materials: polyethylene film, mineral wool, expanded polystyrene boards

Equipment

  • Crawler crane with a lifting capacity of 40 t
  • Transit mixers and dump trucks of appropriate payload capacity
  • Auto-concrete pump with a mobile placing boom
  • Rotary concrete skips (buckets) with a capacity of 0.5–2.0 m³
  • Internal electric vibrators with a flexible shaft
  • Standardized modular demountable metal formwork
  • Assembly jigs (templates) for pre-assembly of reinforcement cages
  • Equipment for electrical heating: 380V/50-106V step-down transformers, strip electrodes, thermo-active formwork
1

1. Preparatory Works and Construction Site Organization

Before commencing the construction of monolithic structures (using the example of a building with grid dimensions of 32.1 x 12 m), a series of preparatory activities must be completed. The pit base must be formally accepted via a handover certificate, with mandatory geodetic verification and the installation of a concrete blinding layer. Surface water drainage and access roads for heavy machinery must be organized.

Climatic conditions of the site (including zones with design winter temperatures down to -34 °C) require the preparation of special areas for storage and pre-assembly. The operating zones of lifting mechanisms (crawler cranes with a lifting capacity of 40 t or more) are marked out, taking into account traffic routes, locations for installation equipment, and connection points for welding stations.

Geodetic setting out of the axes is accompanied by applying indelible paint marks on the surface of the concrete blinding for precise positioning of the formwork panels' working plane. The stock of materials (reinforcement meshes, modular formwork sets) on site must ensure uninterrupted work for at least two working shifts.

Fig. 1 — Detailed floor plan of a multi-unit building indicating structural walls, partitions, staircases, and sanitary layouts
Fig. 1 — Detailed floor plan of a multi-unit building indicating structural walls, partitions, staircases, and sanitary layouts
1Exterior load-bearing wall, indicating structural boundary and primary support
2Interior load-bearing wall or primary partition, providing structural subdivision within the building
3Staircase, indicating vertical circulation between floor levels
4Interior partition wall, delineating individual rooms or spaces within units
5Window opening in exterior wall, indicating position for natural light and ventilation
6Sanitary facility layout, showing proposed arrangement of fixtures such as toilets and sinks
7Door opening, indicating access points between rooms or to the exterior
8Radiused architectural feature or partition, possibly indicating a curved wall or spatial boundary
  1. Organization of surface water drainage and construction of access roads.
  2. Execution of the concrete blinding layer and formal acceptance of the base via a certificate.
  3. Geodetic setting out of axes and application of alignment marks on the concrete base.
  4. Installation of temporary lighting, connection of welding stations, and preparation of assembly jigs for pre-assembly.
2

2. Reinforcement Works and Cage Assembly

Reinforcement of foundation footings and basement walls is performed using prefabricated reinforcement meshes and 3D spatial cages. For basement walls, the assembly of reinforcement cages is carried out on specialized assembly jigs (templates). Meshes are placed on the jig, secured in the design position with tie wire, and subsequently tack-welded in accordance with ISO 17660 requirements for welding reinforcing steel.

Completed cages are slung by a crane and stored within reach. When reinforcing foundation footings, the meshes are unrolled directly in place with the mandatory installation of plastic or fiber-reinforced concrete spacers to strictly ensure the normative concrete cover.

The installation of basement wall reinforcement is carried out after the foundation footing formwork panels are installed. The spatial cage is installed by crane and securely tied to the starter bars or the underlying mesh with tie wire. The entire complex of works is performed by a specialized crew, including a crane operator, riggers, and qualified steel fixers.

Fig. 2 — Layout plan for concreting strip foundations using a self-propelled jib crane
Fig. 2 — Layout plan for concreting strip foundations using a self-propelled jib crane
1Crane stop position No. 1 (Cr. N1), indicating the first location for the jib crane during the concreting sequence.
2Crane stop position No. 2 (Cr. N2), marking the second designated setup point for the crane along the trench.
3Crane stop position No. 3 (Cr. N3), indicating the third location for the jib crane to reach specific foundation sections.
4Crane stop position No. 4 (Cr. N4), marking the final setup point on the upper side of the foundation trench.
5Crane stop position No. 8 (Cr. N8), marking a setup point on the lower side of the foundation trench.
6Concrete transfer bucket (BP-2.0), used to transport concrete from the mixer trucks to the foundation forms via the crane.
7Concrete mixer truck (KamAZ-5511 / SB-92-1A), positioned for discharging concrete into the transfer bucket.
8Crane stop position No. 5 (Cr. N5), marking a setup point on the lower side of the foundation trench, adjacent to the concrete delivery area.
9Longitudinal grid axis B, indicating the central alignment of the structural foundation grid, spaced 6000mm from adjacent axes.
10Longitudinal grid axis V, indicating the upper alignment of the structural foundation grid, defining the overall width of 12000mm.
  1. Laying out the foundation footing reinforcement meshes on distance spacers to ensure concrete cover.
  2. Pre-assembly of basement wall meshes on an assembly jig using tying and electric arc welding.
  3. Installation of the basement wall reinforcement cage into the design position using a crane.
  4. Splicing and fixing the wall reinforcement cage to the foundation footing reinforcement.
3

3. Formwork Operations and Tolerances

To shape the geometry of the foundations, a standardized modular demountable metal formwork is used. Installation begins with securing the foundation footing panels using clamping brackets and assembly angles. Walers are attached to the lower box panels with tension hooks and connected by wedge clamps in a 'windmill' pattern.

Formwork assembly follows strict normative proportions: for every 60 cm of panel height, 1 row of walers is installed; per 1 linear meter of lateral surface, 4 tension hooks and 10 spring clips are mounted; for every 2 linear meters of foundation length, 1 supporting push-pull prop is required. Alignment of the box is performed strictly according to geodetic axes with fixation to the base using metal pins.

Formwork removal is permitted exclusively after the concrete reaches a stripping strength of 1.0–1.5 MPa. Dismantling is carried out in strict reverse order: removal of push-pull props, knocking out wedges, removal of assembly angles, dismantling of support beams, and panels. After dismantling, working surfaces are cleaned with wire brushes and coated with an emulsion release agent.

Fig. 3 — Installation of reinforced concrete columns into foundation cups using a crawler crane
Fig. 3 — Installation of reinforced concrete columns into foundation cups using a crawler crane
1Crawler crane operator's cabin and controls, positioned for optimal visibility
2Lattice boom of the crawler crane, length L=20000 mm
3Precast reinforced concrete column being hoisted into position
4Excavation pit slope, inclined at a ratio of 1:0.5
5Temporary support structures or survey tripods on the ground surface
6Precast reinforced concrete cup-type foundation, installed at elevation -2.900
7Crane lifting tackle and hook block assembly suspending the column
8Crawler crane superstructure, housing the engine and counterweights (model SKG-40)
9Ground level (GL), designated at elevation -0.400
10Excavation pit for foundation installation, bottom elevation at -2.900
11Crawler tracks providing mobility and stability for the crane
12Excavation pit slope, inclined at a ratio of 1:0.5
13Excavation pit slope, inclined at a ratio of 1:0.5
14Structural grid axis V, spaced 6000 mm from axis B
15Structural grid axis B, centrally located between axes A and V
16Structural grid axis A, spaced 6000 mm from axis B
  1. Installation and securing of foundation footing panels, mounting of walers and wedge clamps.
  2. Marking lines on the ribs of the lower box panels and installing support beams at a distance equal to the panel thickness.
  3. Installation of basement wall panels onto the support beams (in batches of 2-3 meters).
  4. Alignment and securing of the formwork panels in a vertical position using push-pull props.
4

4. Concrete Placement and Compaction

Delivery of the concrete mix (recommended classes C20/25 – C25/30) is carried out by transit mixers. For crane delivery, rotary skips with a capacity of 2 m³ are used, slung with a two-leg chain sling with a lifting capacity of 5 t. Alternatively, an auto-concrete pump with a placing boom is used, ensuring concrete placement from 8 setups and cyclic operation.

Concrete is placed continuously in horizontal layers 0.3–0.5 m thick. Each layer is subjected to mandatory vibration using internal poker vibrators. The working part of the vibrator must penetrate the previously placed (still plastic) layer to a depth of 50–100 mm to ensure joint homogeneity. The vibrator insertion spacing must not exceed 1.5 times its radius of action.

To avoid the formation of cold joints, the overlapping of layers must occur before the previous layer begins to set (usually a 1-2 hour gap between the footing and the wall). For long walls, concreting is carried out in pouring bays of 10–12 m with the installation of stop-end formwork forming shear keys in the construction joints. Concrete curing includes protection from solar radiation and regular moistening in accordance with laboratory regulations (according to ISO 22966 series standards).

Fig. 4 — Concreting scheme for a foundation slab using an auto-concrete pump, detailing pump positioning, boom reach limits, and designated pouring blocks.
Fig. 4 — Concreting scheme for a foundation slab using an auto-concrete pump, detailing pump positioning, boom reach limits, and designated pouring blocks.
1Foundation structure limit/formwork line indicating the outer boundary of the reinforced concrete foundation being poured.
2Excavation pit slopes (berms) surrounding the foundation area, providing access and stability during construction.
3Auto-concrete pump outrigger supports (stabilizers) deployed on the access road to ensure equipment stability during operation.
4Articulated boom of the auto-concrete pump extending over the excavation pit to deliver concrete to the designated blocks.
5Maximum operational radius (reach limit) of the concrete pump's boom, shown as a dashed arc, dictating the placement of the pump.
6Active concreting block (shaded area) within the foundation layout, indicating the current section being poured.
7Ramp or access point into the excavation pit with a designated slope angle (30° indicated in original), facilitating equipment or personnel entry.
8Temporary access road or track for the movement and positioning of the auto-concrete pump along the perimeter.
9Axis of movement for the auto-concrete pump, guiding its positioning along the edge.
  1. Receiving the concrete mix into rotary skips or the hopper of an auto-concrete pump.
  2. Placing concrete in 0.3–0.5 m layers from suspended working platforms.
  3. Compacting each layer with an internal vibrator, penetrating the previous layer by 5-10 cm.
  4. Covering exposed surfaces and providing temperature and moisture curing for the concrete.
5

5. Winter Concreting Operations

When the average daily temperature drops below +5 °C and the minimum drops below 0 °C, winter concreting protocols are introduced. For a design surface modulus of the structure of 4.37 m⁻¹, methods such as the thermos method, electrical heating, or the use of anti-frost admixtures are applied. Mixing time at the batching plant and vibration time are increased by at least 25%.

Chemical admixture method: chloride salts (up to 2% of cement mass), potash, or sodium nitrite (up to 5%) are used together with plasticizers. The mix is prepared using heated aggregates; the temperature at discharge is +25...+35 °C, and during placement — not lower than +20 °C (acceptable at outside temperatures down to -20 °C).

Electrical heating is implemented by two methods. The preheating method ('hot thermos') uses 380 V voltage to heat the mix in skips to +70...+90 °C in 5-10 minutes. Peripheral electrode heating uses steel strips (width 2-5 cm, thickness 1-2 mm) at a voltage of 50-106 V. The rate of concrete temperature rise must not exceed 8 °C/hour to prevent thermal deformations. Temperature monitoring is carried out every hour for the first 3 hours, then every 2-3 hours.

Fig. 5 — Cross-sectional diagram of concrete pouring operations for bored piles in an excavated trench using a mobile concrete pump
Fig. 5 — Cross-sectional diagram of concrete pouring operations for bored piles in an excavated trench using a mobile concrete pump
1Soil dump or spoil heap, resulting from the trench excavation, piled on the adjacent ground level
2Bottom of the excavated trench, serving as the working level for pile foundation construction, located at an elevation of -2.900m
3Bored pile with a widened head/cap, installed vertically in the trench, shown during the concrete pouring phase
4Articulated boom of the mobile concrete pump, extending from the truck to deliver concrete directly into the bored piles
5Mobile concrete pump truck (labeled 'SB-126A'), stationed at the ground level to supply and pump concrete
  1. Heating the concrete mix in specially equipped insulated skips up to +70...+90 °C (for the hot thermos method).
  2. Accelerated continuous placement of the heated concrete mix with a free-fall height not exceeding 1.5 m.
  3. Connecting surface electrodes or thermo-active formwork, with a step-by-step voltage increase from 50-60 V to 106 V.
  4. Covering unformed surfaces with a vapor barrier and a layer of thermal insulation immediately after concreting.
6

6. Work Organization and Safety Measures

Specialized crews are formed for the comprehensive execution of monolithic works. Crew No. 1 (operator, erectors, riggers) is responsible for unloading and slinging. Crew No. 2 (steel fixers, welder) performs the tying and welding of meshes. Crew No. 3 (construction fitters) carries out the installation, dismantling, and lubrication of the formwork. Crews No. 4 and No. 5 place the concrete using a crane or pump, respectively.

The installation of formwork elements in multiple tiers is permitted only after the underlying tier is rigidly secured. Storing materials on the formwork decking is strictly prohibited. The free-fall drop height of the concrete mix from the skip must not exceed 1 m to the surface of previously placed concrete.

Particular attention is paid to working with concrete pipelines: assembly, dismantling, and cleaning of pipelines are permitted exclusively after the pressure is fully relieved to atmospheric. When purging concrete delivery pipes with compressed air, all personnel not involved in this operation must be evacuated to a safe distance of at least 10 meters.

Fig. 6 — Crane load chart depicting the relationship between operating radius, lifting capacity, and hook height limits
Fig. 6 — Crane load chart depicting the relationship between operating radius, lifting capacity, and hook height limits
1Lifting capacity curve (solid line) — indicates the maximum safe load in tons relative to the operating radius, demonstrating a decreasing capacity as the radius increases
2Hook height curve (dashed line) — indicates the maximum achievable lifting height in meters corresponding to the given operating radius and load capacity
  1. Per-shift inspection of the condition of lifting eyes, slings, skips, and scaffolding elements.
  2. Barricading the concrete pipeline pressure relief zones and reinforcement pre-assembly zones.
  3. Ensuring reinforcement bars are bundled with end caps installed when passages are less than 1 m wide.
  4. Monitoring the disconnection of electric vibrators during relocation and strictly prohibiting dragging them by their power cables.
Fig. 7 — Construction activity schedule showing task durations and sequencing across days, shifts, and hours.
Fig. 7 — Construction activity schedule showing task durations and sequencing across days, shifts, and hours.
1Task duration bar representing a brief activity scheduled during the first hour of shift 1 on day 1.
2Task duration bar representing an activity scheduled to start concurrently or immediately following task 1, within the first hour of shift 1 on day 1.
3Row label indicating the fourth task or activity stream in the schedule.
4Task duration bar representing an activity spanning the second hour of shift 1 on day 1.
5Task duration bar representing a long-duration activity starting in the third hour of shift 1 on day 1 and continuing continuously through to the end of day 4.
Fig. 8 — Construction project schedule Gantt chart detailing task durations across days, shifts, and hours
Fig. 8 — Construction project schedule Gantt chart detailing task durations across days, shifts, and hours
1Task duration bar — Solid black line indicating a continuous activity spanning approximately four hours in the first shift of day 5
2Task duration segment — Solid black line representing a segment of an intermittent task, occurring in the second half of the first shift on day 5
4Task duration bar — Short solid black block indicating a brief activity lasting one hour in the first shift of day 5
5Task duration bar — Solid black line showing a continuous task extending from the end of the first shift into the second shift of day 5
6Task duration segment — Solid black line denoting a segment of an intermittent task, taking place early in the second shift of day 5
7Task duration segment — Solid black line indicating the final segment of an intermittent task, occurring later in the second shift of day 5
8Task duration bar — Solid black line representing a continuous activity spanning the end of the second shift on day 5 and the beginning of the first shift on day 6
9Task duration bar — Solid black line showing a continuous task lasting for the majority of the first shift on day 6
10Task duration bar — Long solid black line indicating an extended, continuous activity spanning from the end of the first shift on day 6 through the end of the first shift on day 8
Fig. 9 — Example of a cyclic construction schedule (cyclogram) detailing task durations across days, shifts, and hours
Fig. 9 — Example of a cyclic construction schedule (cyclogram) detailing task durations across days, shifts, and hours
1Timeline Header for Day 8, indicating the specific day in the construction sequence.
2Timeline Header for Day 9, indicating the specific day in the construction sequence.
3Timeline Header for Day 10, indicating the specific day in the construction sequence.
4Timeline Header for Day 11, indicating the specific day in the construction sequence.
5Shift Indicator for Day 8, detailing the working shifts within the day.
6Shift Indicator for Day 9, detailing the working shifts within the day.
7Shift Indicator for Day 10, detailing the working shifts within the day.
8Shift Indicator for Day 11, detailing the working shifts within the day.
9Hour Indicator for Day 8 Shifts, breaking down the shift into individual hours.
10Hour Indicator for Day 9 Shifts, breaking down the shift into individual hours.
11Hour Indicator for Day 10 Shifts, breaking down the shift into individual hours.
12Hour Indicator for Day 11 Shifts, breaking down the shift into individual hours.
15General Timeline Area, where the task durations are graphically represented.
Fig. 10 — Construction task scheduling chart detailing operational timelines across days, shifts, and hours
Fig. 10 — Construction task scheduling chart detailing operational timelines across days, shifts, and hours
1Row indicating the overall task or project duration, spanning multiple days and shifts.
2Column header representing Day 12 of the project timeline.
3Column header representing Day 13 of the project timeline.
4Column header representing Day 14 of the project timeline.
5Column header representing Day 15 of the project timeline.
11Row tracking Task 11, showing intermittent activity periods across the scheduled days.
12Row tracking Task 12, indicating short, specific durations of activity at the start of certain shifts.
13Row tracking Task 13, displaying continuous, extended periods of operation throughout the shifts.
15Row tracking Task 15, showing a long continuous block of activity spanning multiple days.
16Row tracking Task 16, detailing a specific, short duration activity occurring late in the schedule.
17Row tracking Task 17, illustrating recurring, intermittent periods of work on specific days.
18Row tracking Task 18, displaying short bursts of activity corresponding to the timing of Task 17.
Fig. 11 — Gantt chart detailing the scheduling of construction operations across multiple days, shifts, and hourly intervals.
Fig. 11 — Gantt chart detailing the scheduling of construction operations across multiple days, shifts, and hourly intervals.
1Overall timeline for Day 8, indicating the scheduling framework for that specific day's shifts and hours.
2Overall timeline for Day 9, indicating the scheduling framework for that specific day's shifts and hours.
3Overall timeline for Day 10, indicating the scheduling framework for that specific day's shifts and hours.
4Overall timeline for Day 11, indicating the scheduling framework for that specific day's shifts and hours.
8Header indicating the specific operational day within the project schedule, subdivided into shifts and hours.
9Header indicating the specific operational day within the project schedule, subdivided into shifts and hours.
10Header indicating the specific operational day within the project schedule, subdivided into shifts and hours.
11Header indicating the specific operational day within the project schedule, subdivided into shifts and hours.
14Bar chart representation of task duration for operation 14, spanning from hour 1 of shift 2 on day 8 to hour 8 of shift 1 on day 9.
15Bar chart representation of task duration for operation 15, scheduled for a brief period during hour 8 of shift 1 on day 9.
16Bar chart representation of task duration for operation 16, scheduled for a very brief period at the start of shift 2 on day 9.
17Bar chart representation of task duration for operation 17, occurring in two segments: from hour 1 of shift 1 on day 9 to hour 2 of shift 2 on day 9, and from hour 1 of shift 1 on day 10 to hour 8 of shift 2 on day 10.
18Bar chart representation of task duration for operation 18, occurring in two segments: from hour 3 to hour 5 of shift 2 on day 9, and from hour 1 to hour 3 of shift 1 on day 11.
Fig. 12 — Formwork assembly for U-shaped reinforced concrete structure with adjustable diagonal bracing.
Fig. 12 — Formwork assembly for U-shaped reinforced concrete structure with adjustable diagonal bracing.
1Outer corner formwork panel intersection, showing butt-joint detail for connecting perpendicular modular panels
2Vertical timber formwork panel, modular unit used for shaping the vertical concrete walls
3Formwork tie/clamp assembly, used to secure horizontal walers and maintain panel alignment
4Horizontal base formwork panel, used for forming the lower projecting slab or footing
5Reinforced concrete structure being formed, consisting of vertical walls and a horizontal base/footing
6Horizontal steel waler (channel or twin-channel section), providing lateral support and rigidity to the vertical formwork panels
7Adjustable diagonal steel strut (push-pull prop), used to plumb and brace the exterior face of the vertical formwork
8Adjustable diagonal steel strut (push-pull prop), used to plumb and brace the formwork for the lower horizontal/step section
9Base plate and anchor for diagonal strut, securing the prop to the ground or existing slab to transfer horizontal loads
Tips & Recommendations
!
When compacting concrete, the vibrator insertion spacing must strictly not exceed 1.5 times its radius of action, and mandatory penetration into the previous layer must be 5–10 cm to prevent cold joints.
i
Formwork removal for load-bearing structures is permitted only after the concrete reaches a strength of 1.0–1.5 MPa. Dismantling is carried out in strict reverse sequence without applying impact loads.
!
During the winter period with electrode heating, the rate of concrete temperature rise must not exceed 8 °C per hour to avoid the formation of critical thermal stresses and microcracks.
i
When concreting highly extended walls (over 20 m), divide the structure into temperature-shrinkage pouring bays of 10–12 m with the provision of special shear keys in the construction joints.
!
When purging and cleaning the concrete pump pipeline with excess pressure, evacuate all personnel to a distance of at least 10 meters. Opening pipeline couplings under pressure is mortally dangerous.
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