The document that shapes the project
The concrete specification in a hydropower EPC tender does more than describe the concrete. It allocates risk between owner and contractor. It defines acceptance criteria. It pre-determines the disputes that will or will not arise during construction. It signals to the bidding contractors how technically demanding the project is, which affects who bids and what they bid.
A well-written concrete specification produces aligned incentives: the owner gets the concrete it needs, the contractor knows what it has to deliver and at what risk, and the QA/QC framework is unambiguous. A poorly written specification produces misaligned incentives, costly disputes, and quality compromises that show up only after the project is in operation.
Most hydropower tender concrete specifications are prepared by senior project engineers who carry over text from previous projects, with limited adaptation. The result is documents that are 80 percent generic and 20 percent project-specific, when they should be 30 percent generic and 70 percent project-specific. This article is for owners, owner’s engineers, and procurement teams who want to do better.
What a tender specification actually has to do
A concrete specification in a hydropower tender must accomplish six things:
- Define the concrete required for each element of the project, in terms the contractor can price and plan against
- Set the acceptance criteria for the delivered concrete, specific enough to be testable but not so prescriptive that the contractor’s expertise is undermined
- Allocate risk between owner and contractor for the various uncertainties (site conditions, material variability, weather)
- Specify the QA/QC framework that governs sampling, testing, acceptance, and rejection
- Reference applicable codes and standards (Indian, international, project-specific) and their hierarchy when they conflict
- Define submittals (mix designs, trial pour records, batch records, test results) and approval workflows
Each of these has to be done clearly, consistently, and at the right level of detail.
Prescriptive vs performance: the foundational choice
The first design choice for a concrete specification is the balance between prescriptive and performance approaches.
| Approach | What it specifies | Owner control | Contractor flexibility |
|---|---|---|---|
| Prescriptive | Mix proportions, cement type, water-cement ratio, named admixtures | High; owner controls the recipe | Low; contractor follows the recipe |
| Performance | Strength, permeability, durability, service life | Medium; owner verifies outcomes | High; contractor decides means |
| Hybrid (most common) | Performance criteria with prescriptive bounds | Balanced | Balanced |
The trend in modern hydropower specifications is toward hybrid: performance criteria for the outcomes that matter (strength, durability), prescriptive bounds on the inputs that drive risk (water-cement ratio, cement content, SCM type and dosage). This gives the contractor flexibility on minor decisions while preserving owner control of the critical ones.
For concrete elements that are unfamiliar to the contractor (RCC dam, mass concrete with thermal control, embedded steel liner concrete), the specification should lean more prescriptive to compensate for the contractor’s likely lack of recent experience. For routine elements (general structural concrete, foundation pads, building frames), performance specifications are usually adequate.
The specification should reflect the contractor's actual experience, not their claimed experience
Owners often write performance specifications assuming the contractor has equivalent experience to a major international firm. The bidder reality is often different: contractors who win on price may have limited recent experience with the specific concrete technology required. The specification should compensate for this with more prescriptive guidance on critical elements, even at the cost of contractor flexibility.
Element-specific specification clauses
A generic concrete specification covers strength grades, water-cement ratio, slump, cover, curing, and standard QC. A hydropower project has elements that need element-specific clauses beyond this generic content.
Mass concrete dam body: thermal control plan requirements, peak temperature limit, differential limit, embedded cooling pipe specifications (where used), pre-cooling requirements, thermal monitoring instrumentation, lift sequencing, contraction joint waterstops per IS 12200.
RCC dam: lift thickness, joint treatment, bedding mortar specifications, placement temperature, compaction requirements (Vebe time, in-place density), seepage control measures.
Tunnel concrete lining: mix design for confined placement, formwork specifications, contact grouting requirements, waterstop placement at construction joints, watertightness test before impoundment.
Powerhouse foundations: mass concrete thermal control for thick blocks, embedment alignment tolerances, second-stage concrete specifications for turbine pit and draft tube zones, machine hall concrete for crane beams and gantry columns.
Spillway and stilling basin: abrasion and cavitation resistance, high-strength concrete or fibre-reinforced concrete for energy dissipator zones, surface finish requirements.
Embedded steel liner concrete: bond enhancement requirements, shrinkage-compensating admixtures (where used), contact grouting procedures and verification.
Repair and rehabilitation concrete (where applicable): repair material specifications, surface preparation requirements, bond strength acceptance criteria.
A specification that omits any of the relevant element-specific clauses leaves the contractor with ambiguity and the owner with risk.
Risk allocation: who carries what
Risk allocation in concrete specifications follows the contract type and the project context. The FIDIC contract suite defines the standard frameworks: the Yellow Book (design-build) typically allocates more design risk to the contractor; the Silver Book (EPC/Turnkey) allocates almost all design and execution risk to the contractor; project-specific contracts can be anywhere between these.
For concrete specifically, risk allocation typically addresses:
| Risk | Default owner | Default contractor | Comments |
|---|---|---|---|
| Foundation rock conditions | Owner | Owner provides rock investigation; contractor responds to actual conditions | |
| Aggregate availability and quality | Mixed | Mixed | Owner approves sources; contractor maintains continuous supply |
| Cement supply disruption | Mixed | Mixed | Owner specifies cement type; contractor procures |
| Ambient conditions (heat, monsoon) | Mixed | Mixed | Owner specifies thresholds; contractor adapts methods |
| Mix design qualification | Contractor | Contractor must qualify for actual site conditions | |
| Achievement of strength | Contractor | Strength testing per acceptance criteria | |
| Defect rectification | Contractor | At contractor’s cost if defect is contractor’s responsibility | |
| Force majeure | Owner | Per contract terms |
The specification should make these allocations explicit through specific clauses. Default contract interpretation can produce inequitable outcomes, particularly for the borderline risks (aggregate quality variation, cement variability, ambient heat extremes).
Allocate risk to the party that can best manage it
The owner cannot manage day-to-day mix design adjustments; the contractor cannot control cement supply chain disruptions. The specification should reflect this reality. Where risks fall on parties that cannot manage them, the project pays a premium in the bid (contractor's risk price) and a premium in disputes during construction. Clear, equitable allocation is the cheapest insurance the owner can buy.
Acceptance criteria: testable, not aspirational
Acceptance criteria should be specific, testable, and unambiguous. Vague criteria invite disputes; aspirational criteria (impossible to actually meet under field conditions) invite either contractor protest or quiet non-compliance.
Compressive strength acceptance typically follows IS 456:2000 (Plain and Reinforced Concrete Code of Practice) Clause 16 statistical acceptance with project-specific modifications. Key questions to answer in the specification:
- Sampling frequency (per cubic metre, per shift, per pour)
- Specimen type (cubes per IS 516 or cylinders per ASTM C39)
- Acceptance criterion (running average and/or individual minimum)
- Procedure for non-conforming results (re-test, core extraction, structural assessment)
Durability acceptance depends on which durability properties are specified. Common tests:
- Permeability per IS 3085 (Method of Test for Permeability of Cement Mortar and Concrete) (penetration depth method) or DIN 1048
- Rapid chloride permeability per ASTM C1202
- Sulphate resistance per ASTM C1012 (where relevant)
- Carbonation depth (where exposure conditions warrant)
Thermal acceptance for mass concrete:
- Peak temperature monitored and limit verified
- Core-surface differential measured during cooling
- Adiabatic temperature rise verified for the qualified mix
The specification should also define what happens when acceptance criteria are not met. Common provisions: re-test, core extraction with revised acceptance criteria, structural assessment, repair, or removal and replacement. The procedural detail prevents the dispute that arises when the path forward is not pre-agreed.
QA/QC framework in the specification
The specification should set out the QA/QC framework, not leave it to the contractor’s discretion or to standard practice. Key elements:
- Sampling frequency for cubes, durability cores, slump, temperature, and other tests
- Testing standards (IS, ACI, ASTM, BS) and which prevails when they differ
- Laboratory requirements (NABL accreditation, on-site lab capabilities)
- Calibration requirements for testing equipment
- Inspection hold points (mix design qualification, trial pour, first production pour, embedment surveys)
- Documentation (batch records, test reports, non-conformance reports, monthly QA/QC reports)
- Reporting and review (frequency, format, distribution)
A common failure mode is a specification that requires extensive testing without specifying who reviews the results, who has authority to accept or reject, and what the response is to non-conforming results. The specification should close these loops.
How to engage a concrete specialist in tender preparation
Most owners benefit from a specialist concrete consultant during tender preparation, particularly for the first hydropower project they have undertaken in some years. The consultant’s role:
- Review the draft specification against current best practice and project-specific conditions
- Identify element-specific clauses that are missing or inadequate
- Calibrate prescriptive vs performance balance to the bidder market
- Review risk allocation against the contract type
- Tighten acceptance criteria and procedures for non-conforming results
- Coordinate with the legal team on contract clause integration
PCCI’s independent review service and mix design service are regularly engaged at the tender preparation stage. Engagement at this stage is significantly less expensive than engagement during construction disputes, and it avoids the disputes altogether in many cases.
How PCCI approaches tender specification consulting
Tender specification review is part of PCCI’s 4,000+ MW portfolio experience, including Punatsangchhu-1 (1,200 MW) where PCCI’s leadership prepared the comprehensive QC manual that became part of the project’s specification framework, and Tanahu (140 MW) where the concrete specification had to balance ACI and ASTM international standards with Nepali project requirements.
Our independent review and QA/QC services are positioned for owners and owner’s engineers preparing concrete specifications for new hydropower tenders.
Book a Technical Call → to discuss your project’s tender specification requirements.
