Concrete
Which concrete diagnostic test answers the repair question?
Match the repair decision to the test, sample the right locations and depths, and combine material, chemistry and field evidence into a usable scope.
Direct answer
Choose concrete diagnostic tests by the repair decision: petrography investigates deterioration mechanisms, ultrasonic pulse velocity maps relative condition, and chloride profiles measure contamination at selected depths. ASTM C856/C856M-25, C597-22 and C1152/C1152M-20 address those different questions. Combine the results with defect locations, reinforcement cover and corrosion evidence to define the repair scope.
On this page
Which test answers each concrete repair question?What should the investigation establish before testing?Petrography versus pulse velocity: which should you order?What does a UPV number mean?Which chloride test should you specify?Which thresholds actually change the repair decision?Where should cores and chloride samples be taken?What belongs on the laboratory chain of custody?How do you combine results that appear to disagree?Worked example: what did the U.S. 52 investigation show?How many analyses should you order, and how long do results take?How do you turn the evidence into a repair scope?Open the related tool for the calculation, checklist, or packet.
FieldOS by AnvilfieldOffline-first FieldOS for job photos, proof packets, property memory, calculations, teams, billing, and owner-ready reports.Which test answers each concrete repair question?
| Repair question | First evidence | Test to order | What the result changes | Source/edition |
|---|---|---|---|---|
| Why is the concrete map-cracking or disintegrating? | Age, exposure, pattern, depth and matched control | Petrographic examination; targeted additional analysis selected from observations | Mechanism and choice between local treatment and broader material response | S2 C856/C856M-25; S10 FHWA 2002 |
| Is an apparently sound zone internally different? | Mapped paths, consistent test arrangement and moisture record | Through-transmission UPV, then selected cores at anomalies and controls | Extent of investigation and sample placement | S1 C597-22 |
| Has external chloride reached the steel? | Cover map, drainage/exposure zones, overlay boundaries | Depth-profile chloride analysis using the specified acid- or water-soluble method | Corrosion assessment and protection/removal design inputs | S3 and S4, 2020; S11, 2016 |
| Is corrosion activity likely in uncoated reinforcement? | Electrical continuity, accessible conductive surface, reference electrode | Half-cell mapping plus chloride/carbonation and physical evidence | Where to investigate corrosion further | S8 C876-22b; S6 FHWA |
| How much material is detached? | Visual map and surface access | Sounding survey; selected cores to confirm depth/interface | Repair quantities and verification openings | S19 FHWA 2006 case |
| Is remaining concrete strong enough for the proposed structural use? | Load path, geometry, test population and design question | Cores for strength testing and structural analysis | Repair, strengthening or replacement design | S7 C42/C42M-20 |
| Will a prepared substrate support a bonded repair? | Defined preparation, surface and acceptance specification | Direct-tension pull-off, with individual failure mode | Preparation or bonding-system acceptance | S20 C1583/C1583M-25 |
| Is freeze-thaw damage consistent with the hardened air-void system? | Saturation, exposure, aggregate/paste distress | Petrography plus C457 air-void parameters | Whether the repair must address a wider durability problem | S22 C457/C457M-24; S10 |
| Is low-chloride corrosion associated with carbonation reaching steel? | Cover, exposure and fresh fractured sample | Carbonation-depth indicator examination plus corrosion evidence | Cause and protection scope | S24 RILEM CPC-18R1, 2026; S8 |
| Does a mix resist chloride penetration? | Mix, age and curing conditions | Electrical indication under C1202 | Mix qualification or specified durability acceptance | S9 C1202-25 |
Start with the decision that would change: local patching, wider removal, corrosion control, a different repair material or structural reassessment. Order evidence for the unresolved part: extent, mechanism, exposure or remaining performance.
ASTM C823/C823M-24 connects examination and sampling to petrographic, chemical, physical and structural testing, so the sampling plan starts with the decision the results must support. Define each population by placement, material and exposure, and state which repair decision its samples represent.
Keep the concrete repair scope separate from the cause investigation until the evidence connects them. Record crack timing and pattern, and map delamination as a physical condition.
What should the investigation establish before testing?
Write the brief as a decision: “Determine whether chloride-driven corrosion extends beyond visible spalls so the removal and protection scope includes affected surrounding concrete.” For map cracking, ask whether material deterioration extends into apparently sound concrete from the same placement. For a debonded overlay, ask whether separation occurs at the interface or within weak parent concrete.
Assemble drawings, placement dates, mix records, leaks, exposure, previous patches, coating history, loading changes and movement observations. FHWA-RD-01-163, March 2002 starts material-distress diagnosis with field observations and carries those findings into sampling and laboratory work. Record the working explanation, its strongest alternative and the observation that would distinguish them.
Map distress and cover, make selected nondestructive comparisons, then collect targeted samples to resolve the remaining questions. The investigation lead selects the evidence; the structural repair designer approves intrusive locations and decisions affecting capacity. Coordinate the core-location and cutting plan, tendon and reinforcement checks, permitted penetration depth and hole reinstatement before collection.
FHWA FLD-DC-MS-001, January 2016 directs crews to use drawings and field detection to locate reinforcement and warns that the lower mat is harder to locate than the upper mat. A top-mat scan does not clear the full drilling depth; resolve the deeper path before coring.
For grouted internal post-tensioning, FHWA-HRT-13-028, October 2013 directs field location of tendons before intrusive access because as-built positions can differ from actual construction.
Petrography versus pulse velocity: which should you order?
Order petrography when the unresolved question concerns constituents or deterioration mechanism; order UPV when a comparison of transmission paths will direct further investigation. ASTM C856/C856M-25 addresses examination of hardened concrete, while ASTM C597-22 addresses longitudinal-wave transmission.
| Method/output | Good use | Cannot establish alone | Main comparability trap | Authority |
|---|---|---|---|---|
| Petrography, material observations and interpretation | Identify constituents and distress mechanisms at sampled locations | Sitewide extent, load capacity or a universal future-expansion rate | Distressed core with no matched reference or field history | S2 2025; S10 2002; S16 2025 |
| UPV, transit time and apparent m/s | Compare paths and locate anomalies | Direct compressive strength or chemical cause | Water, steel, path direction, coupling and geometry | S1 2022 |
| C1152, acid-soluble chloride | Existing chloride concentration by depth | Active corrosion rate or a universal removal boundary | Mass basis, sulfides and aggregate chloride | S3 2020 |
| C1218, water-soluble chloride | Method-defined soluble chloride by depth | All in-situ free chloride or an automatic equivalent of C1152 | Extraction conditions and time-dependent binding | S4 2020 |
| C1202, electrical indication | Compare specified resistance to chloride penetration | Existing chloride mass at reinforcement | Sample age, curing and surface treatments | S9 2025 |
| Half-cell, mV vs named reference | Map probability of corrosion activity in applicable steel | Corrosion rate, section loss or capacity | Nonconductive surface, coated steel, environment | S8 2022b; S6 |
| Rebound hammer, rebound number | Compare surface response; estimate strength with a developed relationship | Chemical cause, uncalibrated strength or acceptance/rejection of concrete | Carbonation, moisture, finish and apparatus/orientation | S23 C805/C805M-25 |
| Pulse echo / impact echo, reflected-wave response | Resolve a thickness or internal-reflector question from one face | Chloride concentration or a directly interchangeable UPV map | Wave type, geometry and reflector interpretation | S15 ACI; S13, 2017 |
| Strength cores, compressive strength | Material input to structural assessment | Deterioration mechanism or sitewide capacity without analysis | Location, orientation, moisture and specimen geometry | S7 2020 |
| Pull-off, stress plus failure location | Prepared surface or bonded-system performance | A bond-only value when failure is in substrate | Combining different failure modes in an average | S20 2025 |
What can microscopy establish about the damage?
Ask the petrographer to describe aggregate and paste condition, crack distribution, reaction products and depth of affected material, then separate observations from the interpreted cause. FHWA’s 2002 material-distress guidance explains why similar visible patterns require laboratory differentiation.
For suspected alkali-silica reaction, establish how reaction features relate to cracking and the field pattern. Identification of reaction products alone supplies neither a future-expansion rate nor member capacity. For shallow finishing problems, compare the affected surface zone with the underlying concrete; the surface-defect diagnosis guide covers the visible distinctions.
For suspected freeze-thaw deterioration, specify ASTM C457/C457M-24 when measured hardened air-void parameters are needed: total air alone does not describe void spacing. Its Procedure C darkens the specimen, so complete other petrographic observations first. Pair damaged and apparently sound material from the same placement and exposure, and connect the findings to the air-void system and freeze-thaw durability.
What does an ultrasonic survey add?
Mapped paths identify relative anomalies and guide core selection. Direct UPV uses opposite faces; indirect UPV places separate transducers on one face. Proceq’s 2017 Pundit 200 instructions identify weaker signals, uncertain path length and surface-zone influence in indirect transmission. Keep the arrangements separate in the comparison.
Pulse echo measures reflected waves, while impact echo uses an impact source. ACI’s public nondestructive-testing guidance distinguishes these methods for questions such as thickness and internal reflectors when opposite-face access is unavailable. GPR and covermeters locate reinforcement for sampling; reinforcement scanning before drilling does not provide chloride concentration or identify a chemical mechanism.
What does a UPV number mean?
Divide transducer separation by pulse transit time to calculate apparent velocity: V = L / t, with L in metres and t in seconds. ASTM C597-22 uses the nominal transducer path; a crack that diverts the pulse lengthens its actual journey and lowers the calculated velocity. Crack orientation changes sensitivity.
ASTM C597-22 does not treat pulse velocity as a measurement of concrete strength; strength estimation needs a relationship established for that concrete. Keep concrete strength-test records with any developed correlation. Universal “excellent”, “good” or “poor” velocity bands do not establish repair acceptance.
Save path coordinates, access arrangement, frequency, couplant, surface preparation, waveform, raw transit time, moisture, temperature and nearby reinforcement. Mark repeat positions before leaving. Reconcile changed moisture or access before reporting improved concrete.
Use the actual instrument manual for operation and the specified ASTM method for interpretation. Proceq’s temperature-correction and strength-correlation functions do not independently validate a strength estimate.
Does a rebound hammer replace strength cores?
ASTM C805/C805M-25, section 5.4 requires at least two replicate cores from each of at least six locations spanning different rebound numbers to establish an in-place strength relationship for the concrete and apparatus. Match surface condition and instrument orientation to the correlation. Manufacturer curves provide relative indications; section 5.5 excludes the rebound method as a basis for accepting or rejecting concrete.
Which chloride test should you specify?
Specify the method and edition, mapped location, depth interval, sample preparation, reporting limit and percentage basis. ASTM C1152/C1152M-20 and C1218/C1218M-20 measure chloride under different extraction conditions, so results must retain their method, sample depth and mass basis before comparison.
Acid-soluble versus water-soluble chloride
C1152 measures acid-extracted chloride, which approximates total chloride in most hydraulic-cement systems. C1218 measures water-extracted chloride under its test conditions; binding, leaching and extraction conditions affect the result. Do not relabel the water-soluble result “all free chloride at the steel”. Both ASTM summaries identify sulfide interference and aggregate chloride that is detected but unavailable for corrosion.
ASTM C1202-25 measures electrical conductance as an indication of resistance to chloride penetration; it does not report existing chloride concentration at reinforcement. Use depth-profile chemistry for existing contamination.
Where do rapid field kits fit?
Germann’s February 1, 2018 RCT certificate distinguishes the acid-soluble RCT-500 procedure from RCTW. It describes improved accuracy after overnight standing and concentration-dependent factors of 1.05 to 1.20 for five-minute results. Record the kit and extraction time, follow its actual procedure and verify decision-critical values with the specified laboratory method. One average correction does not make different extraction methods interchangeable.
Which thresholds actually change the repair decision?
Use a threshold only with its method, material, units and interpretation conditions attached. The historical chloride figures concern corrosion initiation in ordinary-steel bridge concrete; they do not set a universal demolition line or replace new-concrete ingredient limits.
| Quantity | Value or interpretation rule | Applicable condition | Decision and limit | Authority/edition |
|---|---|---|---|---|
| Saturation influence on UPV | Up to 5% higher saturated than dry | Same concrete, different moisture state | Record moisture before interpreting a small difference as damage | ASTM C597-22 public significance/use, S1 |
| Steel influence on UPV | Steel velocity up to twice concrete velocity | Reinforcement near and parallel to path | Avoid or document steel influence; no universal subtraction | ASTM C597-22, S1 |
| UPV minimum dimension | Least dimension exceeds wavelength; calculate wavelength by dividing velocity by frequency | Longitudinal-wave method | Check geometry and frequency before accepting path comparison | ASTM C597-22, S1 |
| Pundit 200 temperature setting | Factor 1.00 at 10 to 30°C; 1.02 at 40°C, wet or dry | Specific instrument instructions | Log setting and raw time; a setting is not a strength validation | Proceq 82032701E ver 11 2017, Pundit 200 section, p. 10, S13 |
| Historical half-cell low-activity band | More positive than -200 mV: 90% probability of no active corrosion | Uncoated steel, Cu/CuSO4 reference, verified continuity and interpretable moisture/oxygen conditions | Pair with chemistry and condition evidence | FHWA summary citing ASTM C876-09, S6; scope: C876-22b, S8 |
| Historical half-cell uncertain band | -350 through -200 mV, including endpoints | Same reference and applicability | Interpret spatial trends and obtain complementary evidence | S6; S8 |
| Historical half-cell high-activity band | More negative than -350 mV: 90% probability of active corrosion | Uncoated steel, Cu/CuSO4 reference, verified continuity and interpretable moisture/oxygen conditions | Investigate corrosion; voltage does not quantify steel loss | S6; S8 |
| Cover influence on half-cell | More than 75 mm can average adjacent potentials | Deep reinforcement cover | Do not assume map resolution equals surface grid spacing | ASTM C876-22b, S8 |
| Historical chloride initiation context | 0.15% soluble chloride by cement mass; about 0.025% by concrete mass for the report's typical bridge mix | Historical ordinary-steel bridge-concrete discussion | State both method basis and mixture dependency; not a universal removal threshold | FHWA-RD-98-088, September 1998, S21 |
| Historical total-chloride context | 0.033% total chloride by concrete mass | Separate FHWA laboratory estimate discussed in the same report | Do not equate with the soluble-chloride value or modern project criterion | S21 |
| Core-strength acceptance example | Three-core average at least 85% of specified strength; no core below 75% | Investigation of low standard-cylinder strength during construction, as described in ASTM's note | Do not use as a blanket acceptance rule for every deteriorated existing structure | ASTM C42/C42M-20 note 4, citing an ACI 318 construction-strength example, S7 |
| Pull-off averaging | Average only results with the same failure mode | Direct-tension surface/bond test | Report each failure location with its stress; project sets acceptance | ASTM C1583/C1583M-25, S20 |
Convert a concrete-mass percentage to cement-mass percentage by multiplying it by concrete mass divided by cement mass. Using Germann’s 2018 certificate inputs of 2,400 kg/m³ concrete and 330 kg/m³ cement, Anvilfield estimates 0.050% by concrete mass as 0.36% by cement mass: 0.050 × 2,400 / 330. Preserve the original result; distinguish cement from total cementitious binder.
What does a half-cell survey establish?
ASTM C876-22b calls for complementary evidence such as chloride, carbonation and delamination data. The corrosion specialist interprets the map with chemistry and exposure; the structural designer determines the significance of measured steel loss.
Verify electrical continuity, the reference electrode and a usable surface circuit; record prewetting, moisture and temperature. FHWA’s January 2016 protocol FLD-DC-NDE-003 identifies oxygen restriction as a cause of unusually negative potentials and requires conversion when interpreting another reference electrode against Cu/CuSO4 values. Dry, high-resistivity concrete and insulating membranes interfere with the circuit. Do not extend uncoated-bar interpretations to epoxy-coated steel, stainless reinforcement or sheathed tendons.
For the separate question of how fast corrosion is occurring, FHWA FLD-DC-NDE-005, January 2016 uses linear polarization resistance to estimate instantaneous corrosion rate. Record electrical continuity, moisture and the steel area represented by the instrument. Measure remaining bar dimensions at selected openings when section loss controls the structural decision.
What if chloride is low but the steel is corroding?
Compare carbonation depth with cover at the same location. RILEM CPC-18R1, published March 4, 2026 describes pH-indicator examination of a fresh fractured surface and the influence of reagent, solvent, binder and reading time. Record those conditions; the colour boundary alone does not establish corrosion rate.
Separate saturated exterior concrete, deiced joints, marine exposure and sheltered surfaces into sampling populations. Match material and placement within each pair so an exposure difference is not confused with a different concrete mixture.
Where should cores and chloride samples be taken?
Sample matched distressed and apparently sound zones, including concrete beyond visible repair edges. Complete a reinforcement cover survey before choosing depth fractions. Record concrete cover, the exposure face, overlay boundary, crack proximity, drainage and prior patches.
For a chloride-exposed reinforced deck, Anvilfield estimates a starting scope of six chloride locations in three exposure/condition pairs, plus two separately allocated petrographic specimens. Coordinates are planned feet from a marked southwest datum, finalized after scanning. All locations receive cover and sounding observations and chloride profiles; use applicable half-cell mapping for corrosion, and add UPV only for an unresolved uniformity question with comparable paths.
| Planned ID / coordinate | Selected condition | Comparison question | Planned evidence | What changes the plan |
|---|---|---|---|---|
| L1 / (10,10) | Distressed concrete beside leaking joint | Corrosion-related cracking or material deterioration? | Photos, cover, sounding, applicable half-cell, conditional UPV path, chloride profile; adjacent petrographic specimen | Scan conflict moves site and coordinate is updated |
| L2 / (20,10) | Apparently sound concrete from same placement and joint exposure | Is the mechanism present outside visible distress? | Cover, sounding, applicable half-cell, conditional UPV and profile; adjacent reference petrographic specimen | Different placement requires a new matched control |
| L3 / (10,30) | Visibly distressed wheel path | Is traffic/exposure zone different from joint zone? | Cover, sounding, applicable half-cell, conditional UPV and profile | Crack crosses sample: identify as crack-path sample |
| L4 / (20,30) | Adjacent intact wheel path, same placement | Does chloride remain high beyond visible distress? | Cover, sounding, applicable half-cell, conditional UPV and profile | Separate intact sample from crack-path material |
| L5 / (10,50) | Ponding/low-point zone | Does water concentration explain contamination? | Cover, sounding, applicable half-cell, conditional UPV and profile; drainage and leak record | Unmapped overlay gets its own depth boundary |
| L6 / (20,50) | Drained comparison zone, same placement | Exposure-driven difference or widespread contamination? | Cover, sounding, applicable half-cell, conditional UPV and profile | Deeper steel requires additional depth fractions |
The exact grid and allocations are Anvilfield design inputs based on C823/C823M-24, FHWA’s 2002 field/laboratory framework and FHWA’s 2016 core records. Agree core diameter, permitted depth, recovered length, mass per fraction, saw losses and retained material with the laboratory and structural sampling plan. Chemistry, petrography and strength testing need their own allocated material. FHWA’s research protocol selects sound sampling locations; this repair plan also samples distress to investigate its cause.
How deep should a chloride profile go?
FHWA’s January 2016 chloride-profile protocol uses six nominal depths from 0.5 to 3 inches, but a repair investigation must extend or adjust those intervals to include the measured reinforcement depth. FLD-DC-MS-004 references AASHTO T 260-97 (2011), procedure A. Its depth template is a bridge-research protocol, adapted here to the repair question.
| Fraction | Nominal depth, in. | Collected interval below sampled exposure face, in. | Intended use |
|---|---|---|---|
| D1 | 0.5 | 0.25 to 0.75 | Near-surface driving concentration in the FHWA protocol |
| D2 | 1.0 | 0.75 to 1.25 | Profile shape; check overlay interface |
| D3 | 1.5 | 1.25 to 1.75 | Profile shape; compare with cover |
| D4 | 2.0 | 1.75 to 2.25 | Steel-depth evidence when steel lies in this interval |
| D5 | 2.5 | 2.25 to 2.75 | Deeper steel or profile trend |
| D6 | 3.0 | 2.75 to 3.25 | Deeper steel or reference trend; extend if needed |
The deepest fraction ends at 3.25 inches; order recovered material reaching that boundary plus preparation losses. Set zero at the sampled exposure face and record the substrate datum separately beneath an overlay. At the Anvilfield plan’s 2.10-inch cover input, D4 brackets steel; at 3.40 inches, extend the profile. Split intervals crossing an overlay boundary or requiring finer resolution at steel.
Each fraction averages its full thickness. Keep crack-path and adjacent intact samples separate, and prevent slurry or powder from crossing depth boundaries. Record wet or dry collection, drilling-water source and tool cleaning. FHWA’s protocol sequences laboratory tests from anticipated lower to higher chloride, commonly deepest first, to reduce cross-contamination.
How many samples are enough?
Six locations with six depth intervals produce 36 separately analyzed fractions in this Anvilfield estimate. Add locations when paired findings disagree or a new placement, exposure or unresolved repair boundary appears; add fractions when the profile misses reinforcement. Size the survey by those populations, rather than applying one core count per floor area.
What belongs on the laboratory chain of custody?
Give every core and depth fraction a unique ID tied to coordinates and photographs. The L1 custody record below contains planned entries. Transfer, authorization and retention fields are Anvilfield’s record design.
| Record field | Filled entry / required action | Basis |
|---|---|---|
| Project and question | Deck diagnostic scope; determine contamination beyond visible distress | Anvilfield form; S5 |
| Parent sample | AF22-L1-C01; planned (10,10) ft; joint exposure; top marked; orientation on sketch | S12; T4 |
| Depth fraction | AF22-L1-C01-D4; 1.75 to 2.25 in. from sampled exposure face; record overlay thickness and substrate datum separately | S11; T5 |
| Collection record | Planned 2026-11-09, 09:00; actual collector, depth, drilling conditions and scan record entered at collection | Anvilfield form; S12 |
| Preservation | Laboratory-approved plan; log actual wrapping and time using the applicable preservation procedure | S12 |
| Transfer | Planned carrier pickup 2026-11-09; actual relinquished/received names, dates and times entered at each handoff | Anvilfield custody design |
| Receipt check | Match package/core/subsample IDs; record intact seal or discrepancy, damage, moisture condition and photos | S11; S12 |
| Requested analysis | C1152/C1152M-20; chloride as % concrete mass; report fraction boundaries and reporting limit | S3; Anvilfield request |
| Allocation | Photograph intact core before splitting; reserve designated adjacent petrographic specimen; no unapproved consumption | S10; Anvilfield allocation |
| Report return | Original data tied to each fraction; method, edition, units, results, reporting limits and exceptions | S11; Anvilfield deliverable |
| Disposition | Retain remaining material until written release; agreed retention period and approver named in lab order | Anvilfield retention agreement |
FHWA’s 2016 wet-core protocol FLD-DC-MS-001 calls for wrapping within one hour in polyethylene, foil, polyethylene and tape after visible drilling water evaporates. Agree preservation with the laboratory for the actual tests. Photograph intact cores and allocate microscopy specimens before destructive preparation.
Reconcile package, parent-core and fraction IDs at receipt. Photograph damage and resolve missing depth marks, broken seals or changed specimen condition before analysis consumes the evidence. Name the person authorized to approve extra preparation, additional tests and eventual disposal.
List laboratory checks and duplicates separately from the base fractions. FHWA FLD-DC-MS-004, 2016 retains detailed titration records, including calibration information, rather than placing all underlying records in the routine report. Request retention of applicable blanks, calibration and titration records. Keep a below-limit result as “less than [reporting limit]”, never zero; resolve a decision near that limit with the laboratory.
How do you combine results that appear to disagree?
Read each result against its location, concrete population, depth and date before combining it with another. In the table, high and low chloride refer to the project’s method-specific criterion; low UPV means lower than comparable reference paths.
| Evidence pattern | Interpretation supported | Next decision/action | What still needs resolving | Basis |
|---|---|---|---|---|
| High chloride at bar depth, strongly negative applicable half-cell map, local delamination | Evidence aligns with chloride-driven reinforcement corrosion | Define physical damage and surrounding corrosion/protection scope | Steel loss and structural significance | S3, S6, S8 |
| High chloride, potentials in the applicable lower-probability band, no delamination | Contamination, corrosion probability and physical damage are different evidence layers | Retain exposure control and monitoring/protection decision | Moisture, conductivity, reference conditions, evolution | S3, S4, S8, S19 |
| Low UPV, chloride below the project criterion, internal cracking on microscopy | Anomaly needs material/physical explanation beyond chloride | Use microscopic diagnosis and exposure history to define treatment | Mechanism and spatial extent | S1, S2, S10 |
| UPV comparable to reference paths, distress mechanism identified in a core | One path result does not erase local material evidence | Map other zones and take targeted comparisons | Orientation, representativeness, severity | S1, S10 |
| High surface chloride, low steel-depth chloride | Exposure established with a different condition at current steel depth | Review protection and future-ingress question | Cover variation, cracks and deeper/hotspot profiles | S11 |
| Pull-off fails in parent concrete rather than interface | Result governed by substrate tensile resistance | Review substrate adequacy for the selected system | Project acceptance criterion and test comparability | S20 |
| Low chloride, carbonation boundary reaches cover, steel corrosion observed | Carbonation is a competing or contributing cause | Define moisture/protection and steel-condition scope | Indicator method, local cover and spatial extent | S24; S8 |
| Petrography inconclusive, field pattern remains unexplained | Current specimen and analysis do not settle the question | Reconcile sample selection/history and request targeted additional work | Specific competing mechanism | S2, S5, S10 |
Anvilfield’s interpretation rule: reconcile location, depth, moisture, method and date first; add testing for the repair decision those checks leave unresolved. The table applies the cited method limits to repair decisions.
Align separate evidence layers on one plan. A material mechanism found in one core requires a spatial comparison before its extent becomes a repair quantity.
Separate present condition, mechanism and forecast in the report. A measured concentration is not a remaining-life estimate: future-ingress calculations also need exposure and transport inputs. Close the current repair decision first, then state the additional inputs needed for a service-life forecast.
Worked example: what did the U.S. 52 investigation show?
FHWA-RD-02-086, August 2006, chapter 4 reports the U.S. 52 bridge overlays at New Richmond, Ohio. Table 19 records no westbound-passing silica-fume-overlay delamination in 1994 and seven areas in 1998. Chemistry, sounding, shear-core results and potential distributions describe different evidence layers within that investigation.
Anvilfield estimates calculated from FHWA observations divide delaminated area by lane area to obtain the affected percentage, and add the three shear strengths then divide by three for their mean.
| Evidence / input | Published result | Anvilfield estimate or interpretation |
|---|---|---|
| Westbound passing lane, silica-fume overlay, 1998 sounding | Seven delaminated areas; total 2.16 m²; lane area 249 m² | Divide delaminated area by lane area: 2.16 / 249 × 100 = 0.87% |
| Same lane, chloride core #1, 1998 | Acid-soluble chloride by concrete mass: 0.119% at 0.25 to 0.5 in.; 0.049% at 0.625 to 1 in.; 0.248% at 1.125 to 1.5 in.; 0.052% at 3.75 to 4 in. | Peak exceeds the deepest result; shallow-only sampling misses it. Record the actual overlay interface before interpreting the peak. |
| Same lane, 1997 core shear results | 4.9, 3.2 and 5.0 MPa | Add strengths and divide by three: (4.9 + 3.2 + 5.0) / 3 = 4.4 MPa, rounded. |
| 1997 shear-core failure observation in chapter narrative | Failures mainly in substrate | Read strength with failure location |
| Westbound passing lane, 1997 half-cell distribution | 96.8% more positive than -250 mV; 88.8% in bins more positive than -200 mV (table 23) | The same distribution gives different percentages at different cut points; retain the threshold with the percentage |
| Combined source conclusion | Generally good overlay performance with limited delamination and evidence of chloride ingress | Use physical condition, chemistry and corrosion evidence together |
Method note: area arithmetic uses FHWA’s 1998 measurements; shear arithmetic uses its three 1997 westbound-passing results. Chloride values are table 30 acid-soluble concentrations by concrete mass, and potentials are table 23 Cu/CuSO4 measurements. These observations come from separate locations and years. Shear-core results are distinct from direct-tension pull-off.
FHWA found generally good overlay performance and limited delamination alongside chloride ingress. Anvilfield’s repair-scope interpretation calls for targeted physical repair plus corrosion/protection assessment: the chloride peak alone does not justify removing the entire overlay. On a new investigation, select UPV for an unresolved uniformity question or petrography for an unresolved material mechanism only when the answer changes that scope.
How many analyses should you order, and how long do results take?
Order 36 chloride analyses for the six-location, six-depth Anvilfield plan. Concrete Research & Testing lists typical completion of one to two weeks after receipt for work without required test timing, checked November 5, 2026. Confirm the laboratory schedule for the actual test package.
| Scope item | Anvilfield estimate / quantity | Order instruction |
|---|---|---|
| Base chloride profiles | 6 locations × 6 intervals = 36 analyses | Specify one chloride method per interval and the concrete-mass reporting basis. |
| Additional six-depth location | 6 more analyses | Use where another exposure or unresolved repair boundary needs a profile. |
| Second chloride method at selected locations | 2 locations × 6 intervals = 12 additional analyses | Keep acid- and water-soluble results separate; confirm enough retained powder. |
| Petrography | 2 separately allocated specimens | State the competing mechanisms, reference location and any additional air-void work. |
| Quality-control samples | Laboratory-agreed count beyond the 36 base analyses | Specify duplicate analyses and field replicates separately. |
| Fieldwork and reporting | Mapped coverage and named deliverables | Include scanning, sampling, access, reinstatement, shipping and integrated interpretation. |
Method note: Anvilfield estimates multiply locations by separately analyzed depth fractions. The base count buys one specified chloride method per interval; a second method adds analyses. Confirm preparation, required mass and retained material before collection, and distinguish a field location from a billable analytical fraction.
A laboratory duplicate checks analytical repeatability; an adjacent field replicate also captures local material and collection variability. Agree which question the quality-control samples answer and how discrepant results will be resolved.
Schedule access and scanning before collection, then shipment, laboratory preparation, testing and integrated interpretation. The laboratory interval starts at receipt. Additional microscopy, specimen conditioning or a second sampling phase extends the investigation; identify the person responsible for each handoff.
How do you turn the evidence into a repair scope?
Build a decision register connecting each repair zone to mapped observations, test IDs, interpreted cause, quantity basis and acceptance requirement. Keep contamination and physical-removal quantities as separate layers until the repair design connects them. State additional-testing triggers and the boundary of structural analysis in the scope.
Use the parking structure restoration program for phasing and access, and the repair guide for execution. Select epoxy crack injection after cause and movement assessment establish its role. Explain why each treatment matches the condition.
For public-owner repair bids, reconcile the investigation report with the bid schedule, unit-price quantities and access restrictions. Keep laboratory analysis, field sampling and interpretation as separate scope lines. An estimator comparing public concrete-repair scopes can find previous award amounts and winning bidders through PorchRocket Bid Control.
Field checklist
- Write the repair decision and the alternative explanations before selecting tests.
- Mark the original surface, exposures, placements, prior repairs and leak paths on one dated base plan.
- Locate reinforcement/tendons and record cover before approving core coordinates and depth.
- Pair visibly distressed and apparently sound locations within the same concrete population.
- Mark UPV paths and record arrangement, frequency, moisture, temperature, raw time and settings.
- Assign a separate ID to every specimen and every chloride depth fraction.
- State the chemistry method, edition, depth boundaries, mass basis and reporting limit in the lab order.
- Reserve petrographic and mechanical specimens before destructive preparation starts.
- Confirm recovered length reaches the last fraction, allocate specimens and include separately specified laboratory checks.
- Record preservation and every custody transfer; reconcile receipt discrepancies before testing.
- Map chemistry, potential, physical damage and material findings as separate evidence layers.
- Resolve mismatched locations, depths, methods and conditions before ordering another test.
- Keep interpretation limits, reference electrodes and analytical basis with results.
- Connect each repair quantity and acceptance requirement to its evidence and decision owner.
- Set repeat measurements at marked comparable locations when exposure, movement, repair performance or an unresolved boundary warrants them.
- Retain the base plan, photographs, raw readings, lab reports, calibration/settings records, specimen log and decision register.
Set repeat testing around the change being monitored: spreading distress, altered exposure, movement or repair performance. Keep the same marked comparison locations and conditions.
Sources and citation record
Anvilfield. Reviewed November 5, 2026. ASTM links identify public publisher summaries; specify the contract edition explicitly. Update log, 2026-11-05: Clarified rebound-hammer acceptance limits, full-depth sampling clearance, chloride sample counts and laboratory ordering.
How to cite this page: Anvilfield, Which concrete diagnostic test answers the repair question?, 2026, https://anvilfield.com/field-guides/concrete/concrete-diagnostic-test-selection/
FAQ
Which concrete diagnostic tests should I order before repair?
Match the decision to petrography for mechanism, UPV for relative condition, chloride profiles for contamination, and complementary tests for corrosion or strength.
Petrography versus pulse velocity: which is better?
Petrography examines the sampled material; UPV compares wave paths, so the useful choice follows the unresolved repair question.
How do I select tests for a concrete investigation?
Define the decision, map the competing causes and select the smallest evidence set that resolves them.
Where should chloride test samples be taken?
Sample matched exposure/condition zones at recorded depth intervals that include measured reinforcement depth.
Can UPV tell me concrete compressive strength?
ASTM C597-22 does not treat UPV as a direct strength measurement; an established relationship for that concrete is needed for strength estimation.
Does a high UPV reading rule out concrete damage?
No; water, reinforcement and crack orientation affect the reading and can obscure a local defect.
Are acid-soluble and water-soluble chloride results interchangeable?
No; C1152 and C1218 measure chloride extracted under different conditions and must retain their method and mass basis.
Is rapid chloride permeability testing a chloride-content test?
No; ASTM C1202-25 gives an electrical indication of penetration resistance rather than existing chloride concentration at the bar.
Does -350 mV mean the rebar has lost strength?
Exactly -350 mV lies at the boundary of the uncertain band in the cited Cu/CuSO4 interpretation. More negative readings indicate corrosion probability under applicable conditions; neither value measures steel loss or capacity.
How many concrete samples are required?
The Anvilfield deck plan starts with six chloride locations in three matched pairs, producing 36 depth-fraction analyses, plus two petrographic specimens. This is a starting scope; add locations or depths for additional populations and unresolved repair boundaries.
How long do concrete diagnostic test results take?
Concrete Research & Testing lists one to two weeks after receipt for testing without required timing, checked November 5, 2026. Confirm petrography and other method-specific timing; add field access, shipment and integrated interpretation.
How often should diagnostic testing be repeated?
Repeat to answer a defined change or monitoring question at marked locations, preserving comparable test arrangements, moisture and other interpretation conditions.
People also ask
Codes cited in this guide
This guide is written and reviewed against the published standards below. Always confirm the current adopted edition with the authority having jurisdiction.
Sources checked
- S1. ASTM C597-22: Ultrasonic pulse velocity Reopened 2026-11-05. Public scope and interpretation summary.
- S2. ASTM C856/C856M-25: Petrographic examination Reopened 2026-11-05. Public scope and interpretation summary.
- S3. ASTM C1152/C1152M-20: Acid-soluble chloride Reopened 2026-11-05. Public scope and interpretation summary.
- S4. ASTM C1218/C1218M-20: Water-soluble chloride Reopened 2026-11-05. Public scope and interpretation summary.
- S5. ASTM C823/C823M-24: Examination and sampling Reopened 2026-11-05. Public scope and interpretation summary.
- S6. FHWA InfoTechnology: Half-cell potential Reopened 2026-11-05.
- S7. ASTM C42/C42M-20: Strength cores Reopened 2026-11-05. Public scope and interpretation summary.
- S8. ASTM C876-22b: Corrosion potentials Reopened 2026-11-05. Public scope and interpretation summary.
- S9. ASTM C1202-25: Electrical indication of chloride penetration resistance Reopened 2026-11-05. Public scope and interpretation summary.
- S10. FHWA-RD-01-163, March 2002: Material-distress investigation Reopened 2026-11-05.
- S11. FHWA FLD-DC-MS-004, January 2016: Chloride profiles Reopened 2026-11-05.
- S12. FHWA-HRT-16-007, January 2016: LTBP protocols Reopened 2026-11-05.
- S13. Proceq Pundit instructions, 82032701E ver 11 2017 Reopened 2026-11-05.
- S14. Concrete Research & Testing: Test Pricing Reopened 2026-11-05. Typical laboratory completion after receipt; no prices reproduced.
- S15. ACI: Ultrasonic pulse velocity and pulse echo tests, public technical answer Reopened 2026-11-05. Distinguishes transmission, pulse echo and impact echo.
- S16. The Concrete Society: Petrographic tests, June 3, 2025 Reopened 2026-11-05.
- S18. Germann Instruments: RCT certificate, February 1, 2018 Reopened 2026-11-05.
- S19. FHWA-RD-02-086, August 2006, chapter 4: U.S. 52 case Reopened 2026-11-05.
- S20. ASTM C1583/C1583M-25: Direct-tension pull-off Reopened 2026-11-05. Public scope and interpretation summary.
- S21. FHWA-RD-98-088, September 1998: Chloride threshold history Reopened 2026-11-05.
- S22. ASTM C457/C457M-24: Hardened air-void parameters Reopened 2026-11-05. Public scope and interpretation summary.
- S23. ASTM C805/C805M-25: Rebound number Reopened 2026-11-05. Public scope and interpretation summary.
- S24. RILEM CPC-18R1, March 4, 2026: Carbonation depth Reopened 2026-11-05.
- S25. FHWA-HRT-13-028, October 2013: Grouted post-tensioning investigation Opened 2026-11-05. Internal tendon location before intrusive access; chapters 6 and 7.