Civily
    Technical reference

    Civil engineering testing library

    Reference material on construction material testing and geotechnics, organised for civil engineering students and professionals.

    19 learning resources
    Discipline

    Asphalt

    08 resources
    GUIDEAsphalt

    Advanced asphalt mixture tests

    Dynamic modulus, flow number, uniaxial fatigue, SCB, and complementary methods.

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    Dynamic modulus

    • Cyclic loading is applied and stress and strain are measured to characterize mixture stiffness.
    • A range of temperatures and frequencies can be used to build a master curve and compare response under different loading conditions.

    Rutting and fatigue

    • A flow-number test tracks permanent strain over repeated cycles; a change in the deformation trend helps compare rutting susceptibility.
    • Uniaxial fatigue cycles a specimen and tracks damage development; interpret results using the model and criteria in the procedure.
    • Repeated-load methods, such as iRLPD or stress sweeps, characterize accumulated deformation under combinations of temperature and stress.

    Cracking and specimen geometry

    • The SCB test uses a notched semicircular specimen to study crack initiation and propagation.
    • The Overlay test examines cracking resistance associated with reflective cracking; indirect-tension configurations can also use field cores.
    • Smaller-diameter specimens may make field cores easier to test, provided their dimensions and representativeness suit the method.

    Interpretation and control

    • Compare results only when geometry, preparation, conditioning, temperature, and loading sequence match.
    • Check alignment, instrumentation, contact, and repeatability. A performance result supports design; it does not replace field validation.
    GUIDEAsphalt

    Binder extraction and recovery

    How to separate binder and fines from a mixture to study its composition.

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    What the test tells you

    • An asphalt mixture combines aggregates of different sizes, filler, and binder. Measuring their proportions helps check the mix formula and investigate deviations.
    • Extraction separates binder from the mineral fraction; sieve analysis can then characterize the aggregate skeleton.

    Main stages

    • Homogenize and record the mass of a representative portion before testing; avoid losing fines during handling.
    • Separate the binder using an extraction method validated for the material and applicable procedure.
    • Separate and recover fines, dry and weigh the mineral fractions and, where the method allows, recover binder for further testing.

    Reading the results

    • Calculate binder content from the initial and final masses, applying the corrections required by the method.
    • Plot the grading of the recovered aggregates and compare it with the job-mix formula or specified limits.

    Good practice

    • Control solvent recovery, sample losses, and moisture: each can bias the mass balance.
    • Solvents can be hazardous. Follow their safety data sheets and laboratory procedure, including suitable extraction, protective equipment, and waste handling.
    GUIDEAsphalt

    Binder ageing and performance

    How climate, ageing, and rheological response relate to asphalt binder performance.

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    From material selection to service

    • Binder selection is part of mix design. Performance grading relates the binder to expected pavement temperatures.
    • Response depends on temperature, loading time or rate, and ageing; one measurement cannot describe all behaviour.

    Conditioning and tests

    • Short-term conditioning represents changes associated with production and paving; long-term conditioning simulates further ageing in service.
    • Rotational viscosity characterizes resistance to flow at the test temperature and helps assess workability.
    • A dynamic shear rheometer applies oscillation to a thin specimen to study stiffness and viscoelastic response; a bending beam rheometer evaluates low-temperature flexure.

    How to compare

    • Compare unaged and conditioned material using the same method and specified temperatures; report each specimen’s ageing condition.
    • Relate high-, intermediate-, and low-temperature tests to risks of permanent deformation, fatigue, and thermal cracking, respectively.

    Scope

    • Binder tests do not replace mixture testing: interaction with aggregates, air voids, and compaction also governs performance.
    • This guide summarizes concepts. Check current standards and project specifications for procedures, temperatures, and acceptance criteria.
    GUIDEAsphalt

    Traditional binder tests

    Penetration, softening point, ductility, and other basic binder properties.

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    What each test measures

    • Penetration estimates consistency at a defined temperature, load, and duration; greater penetration generally indicates a softer binder under those conditions.
    • The ring-and-ball test gives a comparative softening temperature; on its own, it is not a service-temperature limit.
    • Ductility measures how far a specimen stretches before breaking. Elastic recovery measures how much it recovers after deformation.

    How the tests work

    • Condition the binder and containers as required by the method; control temperature, time, geometry, and preparation so specimens are comparable.
    • For penetration, a standard needle is applied and its movement is measured. The traditional procedure described in the source uses 100 g, 25 °C, and 5 s; always check the applicable standard edition.
    • For ring and ball, heat the discs at a controlled rate and record the method-defined temperature. In ductility testing, record elongation and, where required, force.

    Interpretation

    • Interpret values together: each method describes a different aspect, and results depend on temperature and procedure.
    • Viscosity tests help assess pumping and workability; flash-point tests provide safety and control information, not a performance grade.

    Quality control

    • Use the replicates, averages, and tolerances specified by the standard; document unusual results before excluding them.
    • Use thermal protection and control heating: hot binder can cause burns and release fumes.
    GUIDEAsphalt

    Introduction to dynamic mixture tests

    What performance tests reveal about repeated loads, temperature, and traffic.

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    Why test asphalt mixtures

    • Design needs to establish whether a mixture resists permanent deformation and cracking under relevant temperatures and loads.
    • Traditional tests remain useful for control and classification, but empirical indices alone do not represent all pavement behaviour.

    Performance properties

    • Dynamic modulus relates stress and strain under cyclic loading and depends on temperature and frequency.
    • Fatigue resistance describes response to repeated flexure; permanent deformation tests observe the accumulation of unrecoverable strain.
    • Fracture and crack-propagation tests provide complementary indicators of cracking resistance.

    Planning a test sequence

    • Define the engineering question: stiffness, rutting, fatigue, cracking, or production control.
    • Select specimen geometry, conditioning, temperature, confinement, and load signal according to the method.
    • Record the full response, not just the final value, and verify that specimen and test conditions are valid.

    Responsible application

    • Use results to compare mixtures and support design decisions; do not extrapolate beyond the tested materials and conditions.
    • Combine laboratory findings with specifications, construction control, and field data where available.
    GUIDEAsphalt

    Gyratory compaction and wheel tracking

    Compaction under pressure and gyration, and assessment of permanent deformation.

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    Gyratory compaction

    • A hot specimen receives an axial load while the mould rotates at a controlled angle, combining compression and shear.
    • Height or density recorded against gyrations describes how the mixture densifies and helps compare workability.

    Applications

    • The procedure can support volumetric mix design and quality control, as well as produce specimens for other tests.
    • Mass, mould geometry, temperature, pressure, speed, and angle must match the applicable method.

    Wheel tracking

    • A wheel applies repeated loading to a slab or specimen conditioned at a controlled temperature; the movement accelerates a traffic-like action.
    • Rutting depth is measured against passes. Conditioning medium, wheel, and load depend on the chosen procedure.

    Interpretation and cautions

    • Compare curves and final values only with the specified geometry, temperature, load, and acceptance criteria; do not mix protocols.
    • Check parallelism, uniform compaction, and conditioning. Cracks or unrepresentative voids can distort the measured rut.
    GUIDEAsphalt

    Marshall, indirect tension, and cracking

    Static tests for stability, deformation, strength, and cracking susceptibility.

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    Marshall and indirect tension

    • In the Marshall test, a compacted specimen is loaded diametrically at the specified rate; maximum load (stability) and the associated deformation (flow) are recorded.
    • In indirect tension, loading a cylindrical specimen creates internal tensile stresses; peak load is used to estimate indirect tensile strength.
    • Indirect tension can also support moisture-susceptibility assessment when conditioned specimen groups are compared as required by the method.

    Cracking tests

    • SCB loads a notched semicircular specimen and examines energy or response associated with crack propagation.
    • IDEAL-CT uses a cylindrical specimen and its load-deformation curve to estimate a cracking-resistance index.

    Bond between pavement layers

    • Interlayer shear or bond tests measure the force needed to slide or separate materials at an interface.
    • Core preparation, interface plane, temperature, and loading rate must follow the specified procedure.

    Interpretation

    • Peak load alone does not tell the whole story: retain the load-displacement curve and calculate the indices defined by the method.
    • These tests are complementary. Relate them to composition, air voids, and other performance tests before making mix decisions.
    GUIDEAsphalt

    Asphalt mixture specimen preparation

    Sampling, mixing, compaction, and cutting for comparable specimens.

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    Why preparation matters

    • Aggregate distribution, air voids, and density affect mechanical measurements. A poor specimen can produce misleading results even when the equipment is precise.
    • Plan specimen dimensions and quantities before mixing so enough material is available and sample-to-sample variation is reduced.

    Mixing and compaction

    • Condition aggregates and binder at the working temperatures defined by the method, then mix until the material is uniform.
    • Compact using the selected procedure—gyratory, impact, or slab—and record temperature, energy or gyrations, mass, and density.
    • Prepare a slab when the test requires a larger specimen; check uniformity before coring or cutting pieces.

    Cutting and coring

    • Core or cut beams and special geometries using guides that maintain parallel faces, dimensions, and orientation.
    • Check every face, specimen integrity, and final height; reject or document defects that could affect the test.

    Good practice

    • Maintain identification and traceability from the original sample to each specimen; do not mix batches or lose fines.
    • Cutting can create particles, splashes, and entanglement hazards. Use guards, cooling, and laboratory safety procedures.
    Discipline

    Concrete and cement

    05 resources
    GUIDEConcrete and cement

    Aggregate characterization

    Grading, shape, cleanliness, wear resistance, and aggregate durability.

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    Aggregates as the skeleton

    • Aggregates occupy much of the volume in concrete and road layers; size, shape, texture, and strength affect workability and performance.
    • A suitable combined grading helps control voids and the amount of paste required, but must fit the application and specification.

    Sampling and grading

    • Obtain a representative sample and reduce it with a suitable splitter; poor sampling invalidates an otherwise precise grading test.
    • Sieve analysis separates fractions by aperture and calculates retained or passing percentages to build a grading curve.
    • Shape indices and sand-equivalent or methylene-blue tests help identify unfavourable particles and clay-rich fines.

    Strength and durability

    • Abrasion or fragmentation tests compare aggregate resistance to wear and impact.
    • Moisture, salt, freeze-thaw, and weathering cycles explore environmental stability; density and absorption help describe porosity.
    • For pavements, polishing and friction tests provide information about texture evolution and skid resistance.

    Reporting

    • Record source, lot, preparation, mass, sieves, and moisture condition; report the standard and fractions tested.
    • Compare results with current contractual limits. No single test replaces an overall aggregate assessment.
    GUIDEConcrete and cement

    Cement and mortar testing

    Sampling, fineness, soundness, consistency, setting, and cement strength.

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    Hydration and properties

    • Hydraulic cement reacts with water to form a paste that hardens and binds aggregates. Fineness and composition affect hydration rate and strength development.
    • Heat of hydration matters particularly in massive elements, where limited heat dissipation can create thermal gradients and stresses.

    Physical tests

    • Fineness can be estimated by measuring air flow through a compacted cement bed or by sieving, among other methods.
    • Paste consistency is determined by penetration; initial and final setting times are defined by penetration under controlled conditions.
    • Soundness testing looks for delayed expansion; methods such as Le Chatelier or autoclave accelerate detection of expansion tendencies.

    Mortar strength

    • Mix mortar using defined proportions and sequence, mould specimens, and compact them as required by the standard.
    • Maintain controlled curing, temperature, and humidity; specimens may be tested in flexure and then compression as specified.

    Comparability

    • Take increments from several bags or points in a lot and prepare a representative composite sample.
    • Dimensions, penetration thresholds, compaction, and curing differ between standards. Follow the contractual edition and method without mixing requirements.
    GUIDEConcrete and cement

    Fresh and hardened concrete

    Fresh-state workability and uniformity; hardened-state preparation, curing, and durability.

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    Fresh concrete

    • Workability describes how easily concrete can be transported, placed, and compacted without excessive segregation or bleeding.
    • Slump, flow-table, and Vebe tests assess consistency over different ranges; none alone captures every rheological property.
    • Air content, density, segregation, and bleeding may also be assessed. For self-compacting concrete, filling ability and segregation resistance are important.

    Specimen preparation

    • Take a representative sample, mix uniformly, and record time, temperature, and transport conditions.
    • Fill moulds of specified dimensions and compact using the appropriate method to avoid voids or excessive vibration.
    • Identify every specimen and protect it during initial curing to prevent moisture loss or temperature changes.

    Hardened concrete

    • Standardized curing enables comparison of compressive, flexural, and other properties between batches.
    • Loading faces must be flat and parallel; prepare them by grinding or an approved capping method.
    • Density and water-penetration tests provide complementary indicators of porosity and durability.

    Interpretation

    • Relate each result to specimen age, geometry, curing, moisture, and failure mode.
    • Use the current standard to select the test and acceptance criteria; fresh-concrete tests do not replace hardened-strength control.
    GUIDEConcrete and cement

    Non-destructive concrete assessment

    Ultrasonics, rebound hammer, reinforcement location, durability, and monitoring methods.

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    What NDT can and cannot tell you

    • Non-destructive tests help locate anomalies, compare uniformity, and plan investigations on existing structures.
    • An indirect reading rarely gives exact strength by itself; interpret it in light of material, moisture, geometry, and calibration.

    Quality and strength methods

    • Ultrasonic pulse velocity depends on density and elastic properties; voids, cracks, moisture, reinforcement, and transducer contact can affect it.
    • A rebound hammer measures surface hardness. It can compare areas, but conversion to strength requires a suitable correlation, ideally using cores from the structure.
    • Combining ultrasound and rebound can broaden an assessment, but correlations still require validation for the concrete being investigated.

    Durability and monitoring

    • A covermeter estimates reinforcement location and cover before drilling or intervention.
    • Chloride, half-cell potential, and carbonation tests investigate mechanisms that can compromise steel protection.
    • Mechanical gauges, crack gauges, and flat jacks can monitor deformation, crack width, or stress in masonry.

    Inspection planning

    • Divide the structure into zones, take several readings per area, and record location, orientation, and environmental conditions.
    • If strength is needed, calibrate correlations against representative direct tests and document uncertainty; NDT is a diagnostic tool, not a standalone verdict.
    GUIDEConcrete and cement

    Tensile testing of reinforcing steel

    Stress-strain response, yield strength, ultimate strength, and ductility.

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    Why test reinforcing steel

    • Concrete performs well in compression, while reinforcing steel supplies tensile and flexural capacity.
    • Tensile testing verifies steel mechanical properties and supports comparison of batches with the applicable specification.

    Stress-strain response

    • In the elastic region, deformation is approximately reversible; its slope represents elastic modulus.
    • At yield, plastic deformation begins. Strain hardening, maximum load, localized necking, and fracture may follow.
    • Tensile strength and final elongation describe different properties: maximum resistance and deformation capacity.

    Test procedure

    • Measure and mark the gauge length, check diameter or section, and grip the specimen with compatible jaws.
    • Apply axial load under control and measure force and strain using the extensometry method required.
    • Record fracture mode and location; a break at the grip or outside the valid region may invalidate a result.

    Reporting and safety

    • Report yield strength or specified proof strength, maximum tensile strength, elongation, and the control method used.
    • Steel can fragment at failure. Use guards and follow the current standard for rate, extensometer, and specimen validity.
    Discipline

    Soil & rock testing

    06 resources
    GUIDESoil & rock testing

    Soil consolidation and compressibility

    How pore pressure dissipates and how it relates to settlement under loading.

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    Concept

    • In saturated soil, loading can create excess pore-water pressure. As drainage occurs, stress transfers to the soil skeleton and settlement develops.
    • An oedometer compresses a laterally confined specimen to study deformation and consolidation rate under load increments.

    Specimen and sequence

    • An undisturbed sample better preserves structure and moisture; handle it carefully and record orientation and depth.
    • Trim the specimen to fit the ring, mount it between porous elements, and apply the inundation condition specified.
    • Apply load increments and record deformation over time until each stage meets its criterion; unloading and swelling stages may also be included.

    Reading the curves

    • The load-deformation relationship characterizes compressibility; the deformation-time curve describes the rate of the process.
    • Derived parameters help estimate settlement and time, but depend on the model, stress history, and specimen quality.

    Points to consider

    • Distinguish consolidation from immediate deformation and secondary compression; do not attribute all settlement to one mechanism.
    • The source also describes CRS and suction methods. Select a procedure for the soil, geotechnical question, and applicable standard.
    GUIDESoil & rock testing

    Dynamic soil testing

    Small-strain stiffness, seismic waves, and cyclic soil response.

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    Two response scales

    • Dynamic tests span very small strains and larger cyclic loading; stiffness and damping depend on strain level.
    • Maximum shear modulus Gmax describes very-small-strain response and relates to shear-wave velocity and soil density.

    Main methods

    • Bender elements generate and receive shear waves through a specimen; travel time is used to estimate wave velocity and Gmax.
    • A resonant column excites the specimen and measures resonant frequency to estimate stiffness and damping at small strains.
    • Cyclic triaxial and cyclic simple shear apply repeated loading histories to study degradation and deformation and, under suitable conditions, liquefaction susceptibility.

    Preparation and procedure

    • Trim or remould a suitable specimen and mount transducers without damaging it or distorting the signal.
    • Saturate and consolidate to represent the expected stress state when required; then apply the defined stress and strain sequence.
    • Control alignment, frequency, amplitude, confining pressure, and sensor response; check signal quality before interpreting results.

    Geotechnical interpretation

    • Compare modulus and damping at equivalent strain levels; do not treat Gmax as constant stiffness for every load.
    • Use data for dynamic and seismic analysis within the tested range, together with soil characterization and the geotechnical model.
    GUIDESoil & rock testing

    Rock classification and specimen preparation

    Intact rock versus rock mass, discontinuities, and specimen preparation.

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    Intact rock and rock mass

    • Intact rock is the material between discontinuities; a rock mass also includes joints, faults, fractures, weathering, and infill.
    • Rock-mass strength depends on discontinuity orientation, persistence, roughness, infill, and condition, as well as the rock matrix.

    Specimen preparation

    • Select a representative sample, record source and orientation, and inspect weathering or fractures before cutting.
    • Core, trim, and grind faces to the method’s geometric tolerances; poor preparation affects failure mode.
    • Rock properties vary. Document defects and do not treat rock as if it were homogeneous concrete.

    Characterizing discontinuities

    • A joint profilometer allows roughness comparison with reference profiles and estimation of a JRC index.
    • Rebound on a joint wall can support hardness assessment; a tilt test provides an empirical observation of friction angle.
    • Direct shear across a joint evaluates sliding resistance under a defined normal stress.

    Durability and application

    • Water-durability or abrasion tests study degradation relevant to fill, rockfill, excavation, and building stone.
    • Interpret results with geology, project scale, and rock-mass structure; one specimen value does not represent an entire rock mass.
    GUIDESoil & rock testing

    Uniaxial and triaxial rock testing

    Compressive strength, confinement effects, and failure-envelope analysis.

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    Uniaxial and triaxial compression

    • In uniaxial compression, a cylindrical specimen is loaded axially without lateral confinement to study strength and stress-strain response.
    • In triaxial compression, a cell adds lateral pressure; repeating the test at different confinements shows how strength changes.

    Preparation and instrumentation

    • Use specimens with dimensions, faces, and parallelism that meet the method; record lithology, orientation, defects, and moisture.
    • Measure load and axial strain; strain gauges or other local sensors can provide radial strain and Poisson’s ratio.
    • For triaxial tests, check the sleeve seal, cell alignment, and stability of confining pressure.

    Failure and envelope

    • Identify peak strength and strain; where control permits, observe post-peak response or residual strength.
    • A series of confining pressures can define failure points and estimate a strength envelope within the tested range.
    • The Brazilian test loads a disc diametrically to estimate indirect tensile strength; geometry and contact must meet the procedure.

    Safety and application

    • Rock may fail brittly and eject fragments. Install guards and keep people outside the projection zone.
    • Interpret results alongside discontinuities and rock-mass scale; intact-rock strength is not automatically rock-mass strength.
    GUIDESoil & rock testing

    Direct shear and residual strength

    Shear strength, normal-stress effects, and residual soil strength.

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    What it measures

    • In direct shear, two halves of a box impose a defined sliding plane while a normal load is applied.
    • Shear stress against displacement shows peak resistance and, after repeated movement, may reveal residual strength.

    Typical sequence

    • Prepare a specimen of known dimensions, place it in the box, and record its condition, density, and moisture.
    • Apply the selected normal stress and allow consolidation where required by the method.
    • Move the box halves at the specified rate and record shear force, displacement, and vertical deformation.
    • Repeat at several normal stresses to construct a strength envelope.

    Residual strength and related methods

    • During back-and-forth cycles or large displacement, strength may stabilize at a residual level; interpret each cycle, not just the initial peak.
    • Ring shear can maintain the shear area over large displacement, although it commonly uses remoulded material.
    • A laboratory vane is useful for a rapid strength assessment in soft clay, following its own procedure.

    Limitations

    • The shear plane is imposed by the box and stress distribution is not uniform; consider these limitations when applying parameters to the ground.
    • Shear rate must allow the required drainage condition. Report stresses, rate, corrected area, and strength criterion according to the standard.
    GUIDESoil & rock testing

    Soil triaxial testing

    Saturation, consolidation, and shearing under confinement: UU, CU, and CD tests.

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    What the test can show

    • A cylindrical specimen receives lateral pressure in a cell and axial load; stresses are controlled and, depending on instrumentation, pore pressure and volume change are measured.
    • The test helps evaluate strength, deformation, and response under stress and drainage conditions relevant to geotechnical problems.

    Common stages

    • Prepare and mount the specimen with membrane, porous stones, and sealed connections; remove air from lines and transducers.
    • Saturate when required and check the specified saturation criterion.
    • Consolidate under the intended effective stress until volume or pressure response meets the completion criterion.
    • Shear at a rate compatible with the drainage condition and measure load, axial deformation, pore pressure, and volume where applicable.

    UU, CU, and CD

    • UU: no consolidation and no drainage during shear; used to study rapid, short-term conditions.
    • CU: consolidate first, then prevent drainage during shear; measuring pore pressure can provide total- and effective-stress responses.
    • CD: consolidate and allow drainage during shear; the rate must be slow enough to dissipate pore pressure.

    Analysis and control

    • Relate principal stresses to strain; a series of specimens at different confining pressures can define a failure envelope.
    • Select the test type for the duration of the problem and field conditions. Do not interchange total and effective parameters without checking the analysis.
    • Durations in the source are illustrative: actual time depends on soil, drainage, specimen size, and the standard criterion.

    Learning guides based on technical presentations, written to make civil engineering materials and test methods easier to understand.