Articles

Chloride Migration Testing: A Critical Factor For Durability Design Of Concrete Structures

Why Chloride Migration Testing:

Due to very high construction costs and the socio-economic importance of civil engineering structures, the durability demand for civil engineering structures is increasing, hence pushing for longer and longer service life design. 

The service life and durability of reinforced concrete structures are affected by the degradation of concrete and corrosion of reinforcement. One of the main aspects of the durability design approach is to restrict the movement of the aggressive ions into the concrete (i.e. chloride ions). Chloride-initiated corrosion is one for the major causes of early age deterioration of concrete structures. Figures 1a and 1b below show the effect of corrosion on reinforcement and subsequent delamination and spalling of concrete due to corrosion.

 

 

Figure 1: Chloride-induced corrosion of reinforcement in concrete structure

Available Test Methods:

Chloride ingress into the concrete is usually a long-term and complex phenomenon involving diffusion, capillary absorption, and permeation. For this reason, tests to determine the rate of chloride ingress through concrete provide valuable information on the long-term durability performance of a structure. Test methods used in Ireland and in Europe are EN 12390-18:2021 ‘Testing hardened concrete – Part 18: Determination of the chloride migration coefficient’ and NT Build 492 ‘Concrete, mortar, and cement-based repair materials: Chloride migration coefficient from non-steady state migration experiments’. These tests are used to determine the chloride migration coefficient for concrete and mortar. 

Both EN 12390-18:2021 and NT Build 492 test methods are based on the non-steady state migration of chloride ions. The test results are used as a durability indicator with respect to the resistance of the concrete to chloride penetration. 

Infrastruct AMS Ltd provides both EN 12390-18:2021 and NT Build 492 test methods for determining the chloride migration coefficient of concrete. We use the Proove’it system, this system was developed by Germann Instruments in Denmark. Figure 2 shows Proove’it chloride migration test set-up.

Chloride Migration Testing - Figure 2
Figure 2: Chloride Migration Test using Proove’it System determining the Migration coefficient on 6 samples of concrete

How the Chloride Migration tests are performed:

Migration testing is performed on concrete cylindrical specimens of 100 mm diameter prepared at project site. The specimens are cured for 28 days before the performing the tests (recommended). However, the tests can be performed on the cored specimens as well.

After the required pre-conditioning, where necessary, the test specimen is placed in designed cells with reservoirs at each end. The reservoirs are filled with a chloride free and chloride containing solution (different solutions are prepared for different tests). An electric voltage is applied between two external electrodes to rapidly force the chloride ions into the concrete specimen. Figure 3 shows a typical cell arrangement according to the NT Build 492 test method.

Chloride Migration Testing - Figure 3
Figure 3: A typical cell arrangement according to NT Build 492 test method using the Proove’It system

After a defined period of time, the specimen is removed from the cells and split. The penetration depth of the free chloride ions is determined using a suitable colour indicator solution. The chloride migration coefficient is then calculated based on the measured depth of penetration in the concrete, the magnitude of the applied voltage and other measured parameters. Figure 4 shows the boundary of the free chloride (white / blueish colour) within the concrete specimen.

Chloride Migration Testing - Figure 4
Figure 4: Chloride penetration as indicated by the white/blueish colour change on the concrete

How the test is useful to Engineers:

The chloride migration coefficient is an indicator for the durability and long-term performance of concrete. The test methods described above will help designers, concrete technologists concrete producers and engineering consultants to assess the durability performance of concrete before construction commences, during the construction phases and after placement. 

Migration testing will help to improve the durability assessment for concretes in civil engineering structures. 

For more information on the chloride migration testing on concretes in Ireland, please contact Dr Thomas Callanan in Infrastruct Asset Management Services Limited.

Articles

Concrete Quality Testing on Pad Foundations

Infrastruct was requested by our Client to determine the in-situ quality of concrete in recently placed pad foundations using non-destructive techniques. We recommended the following combination of test systems:

    1. Proceq PUNDITLab+ UPV test system with 54kHz exponential transducers
    2. MIRA Pulse Echo tomograph using 48 pairs of dry contact transducers.

UPV Testing on the Pad Foundations

Ultrasonic Pulse Velocity measurements were carried out using the Proceq PUNDITLab+ equipment.

UPV testing on concrete elements is a recognised non-destructive evaluation method to qualitatively assess concrete integrity. The measurement of pulse velocity is frequently used to determine the in-situ uniformity of concrete, the presence of cracks or voids in concrete, crack depth estimation and to indicate changes in properties of the concrete with time.

The PUNDITLab+ UPV test system consists of an electric pulse generator, a pair of transducers, in this case 54kHz exponential transducers and an electronic timing device for measuring the time interval between the onset of a pulse generated at the transmitting transducer and its arrival at the receiving transducer.

The pulse cannot travel through air and measurements around voids/cracks/air filled anomalies in the concrete will increase the path length resulting in lower velocities and indicating a reduction in concrete quality. 

Different configurations of the UPV test are possible but for the assessment of concrete quality in these pad foundations, the Infrastruct team used a linear array on a grid layout.  Figure 1 below shows the linear array used on site and Photograph 1 shows the team on site measuring the UPV values for the in-situ concrete.

Concrete Quality Testing on Pad Foundations
Figure 1: UPV linear array used for assessment of concrete quality in concrete
Concrete Quality Testing on Pad Foundations
Photograph 1: UPV testing on concrete pad foundations

MIRA Pulse Echo Tomography

The pulse echo testing on the surface of the concrete pad foundations, as shown in Figure 2 below, was carried out using the Acoustic Control Systems A1040 MIRA ultrasonic low frequency tomograph.  The MIRA test system is intended for inspection of concrete, reinforced concrete and a stone with one-sided access for the purpose of evaluation of consistency of construction, searching for foreign inclusions, cavities, voids, delaminations and cracks in concrete and measurements of concrete thickness.

Concrete Quality Testing on Pad Foundations
Photograph 2: MIRA Pulse Echo testing to evaluate the consistency and integrity of the concrete in the foundation

The MIRA pulse echo test system utilises 45 transmitting and receiving transducer pair measurements in a short scan resulting in a 2-d depth profile of the concrete under test as shown in Figure 2. The dry point contact transducers provide the necessary consistency of impact and wave front penetration for diagnostics deep within the concrete element under test. 

Concrete Quality Testing on Pad Foundations
Figure 2: MIRA Tomography array for scanning concrete elements

The MIRA measurements are taken by placing the transducers flush to the surface for a b-scan measurement, see Photograph 2 above. A b-scan is a 2-dimensional reconstruction of the concrete directly below where the scan is taken, see Figure 3 below. The MIRA system can also be used to create 3-d imaging of the concrete element under test and this can indicate the size and extent of located defects within the concrete.

Concrete Quality Testing on Pad Foundations
Figure 3: MIRA pulse echo image of concrete from the top surface showing one minor anomaly within good quality concrete

The results of the UPV assessment and MIRA testing on the concrete pad foundations were recorded on-site by our Engineers and a comprehensive report, with interpretation, was prepared for our Client.

For more information on the UPV testing or pulse echo tomography, please contact Dr Thomas Callanan in Infrastruct Asset Management Services Limited.

Services

Structural Testing

Structural Testing

The requirement to manage and maintain structures to a high level of structural safety, durability and performance is of fundamental importance to the owners and operators of the structures. There are many types of structures in-service and classifying the maintenance demands of structures is challenging and often requires a Special Inspection incorporating structural testing and investigations.

Infrastruct provides our Clients with a wide range of specialist testing services focused on giving accurate and structure-specific condition information on their structure(s) for follow-on structural assessments, targeted repairs or rehabilitation designs.

Infrastruct provides a rapid, reliable and structure focused testing and investigation service using modern testing equipment and techniques. All our services are carried out to the latest European and British Standards where possible and the test results and related information are provided in a detailed report with interpretation and AutoCAD drawings.


We carry out testing and investigations on all type of structures including:


Our Structural Testing Services Include:

1) Structural Inspections & Engineering Surveys:

  • Building and structural inspections with defect mapping services
  • Building and structural condition assessments
  • Preparation of structural details and engineering drawings (ACAD & MicroStation)
  • Structural Condition Reports
  • Defect Mapping and Monitoring Reports

2) Concrete Testing (NDT & Intrusive Services)

  • Compressive strength assessment for concrete
  • Corrosion assessment of embedded reinforcement
  • Reinforcement cover and layout surveys
  • Ultrasonic Pulse Velocity (UPV) surveys
  • Permeability of concrete
  • Pull-Off testing (strength, repair or waterproofing)
  • Assessment of deterioration mechanisms
  • Chemical and laboratory investigations
  • Diamond coring (various core sizes)
  • Impact Echo, Pulse Echo and Impulse Response Testing
  • Alkali–Silica Reaction (ASR) Investigations

3) Structural Monitoring & Load Testing Services

  • Monitoring the in-situ performance of structural elements
  • Load testing of structural elements (proof load tests)
  • Load testing of cantilevered stone stairs (existing and new stairs)
  • Load testing of precast concrete elements

4) Steel Testing (NDT & Intrusive Services)

  • In-situ estimation of tensile strength
  • Yield strength determination
  • Ultrasonic thickness measurements
  • Portable hardness testing
  • Magnetic Particle Inspection (MPI)

5) Paint Testing (NDT & Intrusive Services)

  • Visual inspection
  • In-situ thickness measurements
  • Adhesion testing

6) Materials Assessment

  • Material quality assessments
  • Defect investigations
  • Laboratory Services

7) Anchor Testing and Proof Loading

  • Anchor testing for all applications (tensile loading)
  • Scaffold Tie testing
  • Precast concrete lifting elements
  • Precast concrete slab lifting elements

8) Reservoir & Tanks

  • Leak monitoring and assessment (with testing services)
  • Cleaning and Chlorination services to EPA Advice Note 10
  • Reservoir Inspection – confined space entry and technical report
  • Waterproofing and coating assessment
  • Repair and Restoration work conformity assessment
Services

Concrete Testing

Concrete Testing

The performance of concrete structures can change with time and the effect of various deterioration mechanisms can certainly lead to a reduction in the structure’s performance over time.

At Infrastruct, our team is very aware of the changing performance of concrete structures and we provide a range of testing and investigation services to help Engineers and Designers to categorise and assess any type of concrete structure.


Our range of testing and investigation services are used on many types of building and civil engineering structures including:


Our Concrete Testing Services Include:

1) Reinforcement Surveys

  • Covermeter Surveys
  • Ground Penetrating Radar (GPR) Surveys
  • Reinforcement Mapping
  • Targeted Breakouts

2) Corrosion Surveys

  • Delamination Surveys
  • Half-Cell Potentials Surveys
  • Resistivity Surveys
  • Linear Polarisation Resistance (LPR) Measurements
  • Sampling and Chemical Analysis
  • Moisture Content Measurements
  • Targeted Break-Outs
  • Carbonation Depth Measurements
  • Permeability Measurements

3) Concrete Strength Testing

4) Concrete Integrity Analysis

  • UPV Surveys
  • Impulse Response Testing (s’MASH)
  • Pulse Echo Imaging and Testing (MIRA)
  • Impact Echo Testing (DOCtor and CTG2)

5) Concrete Defect Assessment

  • Visual Assessment
  • Delamination Surveys
  • Crack Mapping and Analysis
  • Crack Monitoring (Crack Tell-Tale Gauges, Metal Studs)
  • Physical and Chemical Attack Assessment
    • Freeze-Thaw Attack
    • Fire Damaged Concrete
    • Alkali–Silica Reaction (ASR)
    • Sulphate Attack
    • Chloride-Induced Corrosion

6) Laboratory Testing

  • Concrete Density
  • Alkali Content
  • Chloride Ion Content
  • Cement Content
  • Sulphate Content
  • High Alumina Cement (HAC) Assessment
  • Moisture Content
  • Petrography
Services

Non-Destructive Testing (NDT)

Non-Destructive Testing (NDT)

Knowledge of the in-situ condition of a structure is critical when undertaking an assessment of any type of structure.

Aging may have caused some loss of performance and the previous or current use of a structure may have resulted in degradation and/or deterioration. Defects are not always readily visible on the surface of structural elements.

At Infrastruct, we have a range of Non-Destructive Testing (NDT) equipment in-house for in-situ assessment of the condition of many types of structural elements and structures.

Some of the available equipment and range of testing services are listed below. For more information on these services or any construction-related testing, please contact us.

Concrete Structures:

Test Equipment (In-house) Description of the Testing Service
Covermeter We have a range of covermeters for reinforcement mapping and reinforcement surveys on structures
Ground Penetrating Radar (GPR) High frequency GPR for the location of embedded elements in concrete structures
Rebound Hammer We have two types of rebound hammers in-house for assessment of concrete uniformity and estimation of in-situ compressive strength
Type N: Normal concrete elements >100mm thick
Type L: Thin concrete elements <100mm thick
s’MASH Impulse Response Non-destructive test system for rapid identification of defects or changes in concrete structures
MIRA Pulse Echo Tomography Advanced concrete imaging system to non-destructively examine concrete elements to a depth of up to 2m.
The thickness of the elements can also be determined using this system to a depth of up to 2m
DOCter Impact Echo Non-destructive test system to identify the presence of anomalies in concrete structures and to determine the depth of the concrete elements when only one face is available for testing
CTG2 Impact Echo Rapid measurement of the depth of the concrete slabs and other elements when only one face is available for testing
PunditLab+ Ultrasonic Pulse Velocity Assessment of in-situ concrete quality and estimation of crack depth in concrete elements
GWT (Germann Water Permeation Test) Assessment of water penetration and determination of the permeability of concrete elements
Delam Tool (with microphone) Rapid location of delamination in concrete structures including car parks and reservoir structures
CMEXpertII Moisture meter Measurement of the moisture content of concrete elements including floors, roof structures and walls
In-situ RH% probes are also available from Infrastruct for monitoring the RH% condition in concrete floors
Crack Microscope Accurate measurement of crack widths in concrete structures

Steel Structures:

Test Equipment (In-house) Description of the Testing Service
Portable Hardness Gauge In-situ non-destructive (indirect) test for the measurement of the hardness of metal elements
Zonotip+ Ultrasonic Thickness Gauge In-situ non-destructive test to measure the thickness of ferrous and non-ferrous metals as well as parts made from polymers, glass, ice, and other materials with a low ultrasonic attenuation

Masonry Structures:

Test Equipment (In-house) Description of the Testing Service
OS-120 Rebound Hammer In-situ non-destructive testing on mortar joints in masonry construction.  The mortar can be classified based on a rebound value
GWT (Germann Water Permeation Test) In-situ assessment of the water permeation properties of masonry panels

Test results and related information are provided in a detailed report with interpretation and AutoCAD drawings.

Services

Load Testing

Load Testing

There are many reasons for load testing of structures and at Infrastruct, our team has extensive experience and knowledge of carrying out load testing and monitoring the performance under specified loading.

Load tests check the behaviour of structural elements under known load, establish a proven load capacity and provides Clients, Engineers and Designers with a high degree of assurance for the future use of the structure.

The team in Infrastruct can undertake in-situ, full-scale load testing of floor slabs, floor beams, columns and stairs, including cantilevered stone stairs to check the behaviour of these elements under a specified load, confirm the real load carrying capacity of the element and provide actual data for the assessment of future uses.


Our Load Testing Capability Includes:

All load tests are monitored using calibrated, digital deflection gauges connected to a laptop using a Bluetooth connection.


Our Load Testing Services Includes:

  • Stairs Load Testing
  • Cantilevered Stone Stairs Load Testing
  • Floor Slab Testing
  • Lift Shaft Beam Testing
  • Beam Load Tests
  • Balcony Load Testing
  • Barrier Load Testing
  • Balustrade Load Testing
  • Sporting Ground Crowd Barrier Testing
  • Marine Planks Load Testing
  • Fencing (post and panel) Testing
  • Precast Concrete Element Testing
  • Anchor Testing

Test results and related information are provided in a detailed report with interpretation and AutoCAD drawings.

For more information on load testing or any construction-related testing, please contact us.

Services

Anchor Testing

Anchor Testing

Infrastruct Asset Management Services Ltd. provides our Clients in the construction sector with a range of specialist testing services including general purpose and specialist anchor and fixings testing in both tensile and shear load arrangements.

Our experienced engineering team can carry out all anchor and fixings testing in accordance with the relevant Irish, British and European Standards including the latest version of BS 8539: 2012 ‘Code of practice for the selection and installation of post-installed anchors in concrete and masonry’.



Our Anchor Testing Services Include:

  • Tensile testing of anchors and fixings
  • Shear testing of anchors and fixings
  • Testing of fall arrest anchor points on buildings
  • Load testing on post-installed rebar
  • Failure inspection and analysis
  • Single fixing testing / multiple fixing testing
Services

Corrosion Testing

Corrosion Testing

Reinforcement corrosion is an electrochemical process and is one of the main causes of reinforced concrete deterioration worldwide.

At Infrastruct, we provide a range of corrosion tests for the evaluation of corrosion on reinforced concrete structures such as motorway and road bridges, single and multi-storey buildings, tunnels, dams, drinking water reservoirs and concrete tanks.

The effect of corrosion within a reinforced concrete structure may not always be visible until cracking or rust staining appears on the surface of the concrete and therefore, corrosion testing is recommended when assessing the condition of any structure.


Two processes that commonly initiate corrosion in reinforced concrete during the service life of a structure are:

1) Ingress of chloride ions into the concrete: The penetration of chloride ions into concrete disrupts the passive layer on the reinforcement and allows for localised and very aggressive corrosion on the reinforcement

2) Carbonation penetration into the concrete: the process reduces the alkalinity of the concrete around the reinforcement and changes the local passive conditions enabling corrosion to initiate and propagate on the reinforcement


At Infrastruct, we provide the following testing to assess the corrosion activity on structures:

  • Half-Cell Potential surveys
  • Resistivity surveys
  • Linear Polarisation Resistance measurement and surveys
  • Covermeter surveys
  • Concrete breakouts (targeted openings in the concrete to visually examine the type and severity of the corrosion)
  • Carbonation testing and measurement
  • Sampling and analysis for chloride ion penetration and modelling of the rate of ion penetration into the concrete

Test results and related information are provided in a detailed report with interpretation and AutoCAD drawings.

For more information on corrosion testing or any construction-related testing, please contact us.

Services

Concrete Strength Testing

Concrete Strength Testing

Infrastruct provides our Clients with a wide range of practical solutions for both Intrusive and Non-Destructive (NDT/NDE) evaluation of concrete strength on many types of structures including motorway and road bridges, single and multi-storey buildings, tunnels, dams, drinking water reservoirs and concrete tanks.

An evaluation of the compressive strength of hardened concrete is frequently required in the construction industry. There are many reasons to assess the compressive strength of concrete including:

  1. A requirement by the designers to verify the compressive strength in an existing structure that will be structurally modified, redesigned for other uses or where the structure was damaged i.e. fire.
  2. A requirement to check the structural adequacy in the case of a non-conformity of the standard cube test (or when cube results are not available to the designers.
  3. In the case of a dispute over concrete quality or defective workmanship in new construction works.

The main Standard providing information on the approaches to be adopted as part of an evaluation is I.S. ‘Assessment of in-situ compressive strength in structures and pre-cast concrete components’.

I.S. EN 13791:2007 provides guidance on direct (cores) and indirect (Rebound Hammer, Ultrasonic Pulse Velocity and Pull-out Force) methods for assessing the in-situ compressive strength of hardened concrete.


At Infrastruct, we provide the following testing to assess compressive strength of hardened concrete:

  1. Diamond coring of the concrete elements and structures – Core diameters: 50mm, 75mm, 100mm, 150mm
  2. Rebound Hammer testing (normal and early age concrete testing)
  3. Ultrasonic Pulse Velocity (UPV) testing
  4. SonReb testing and analysis
  5. Capo and Lok testing

Test results and related information is provided in a detailed report with interpretation and AutoCAD drawings.

Also, as part of our Services, we can work with our Clients to monitor strength development in early age concrete structures using the Maturity method (ASTM C1074). This is a non-destructive testing approach that allows us to estimate the early-age and compressive strength of in-place concrete in real-time. The technique is based on the principle that concrete strength is directly related to its hydration temperature history.

For more information on this or any construction-related testing, please contact us.

Services

Structural Inspections

Structural Inspections

Infrastruct is focused on providing a quality based, cost effective inspection, testing and investigation services using our best resources to fully understand the in-situ condition of structures.

Our team is highly experienced in the inspection and investigation of all type of building and civil engineering structures and we have the safety related training including, confined spaces entry, MEWP operations, abrasive wheels, manual handling and Safe Pass to carry out our Client’s requirements.

Structural Inspection of structures include:

  • Motorway and regional route bridges
  • Drinking water reservoirs
  • Liquid retaining concrete tanks
  • Multi-storey buildings
  • Single storey buildings
  • Tunnels
  • Basements
  • Industrial buildings
  • Open framed structures
  • Marine Jetties and Piers
  • Heritage structures
  • Agricultural structures

All our structural inspections are completed by a Chartered Engineer and the inspections and test results are provided in a detailed report with interpretation and AutoCAD drawings


Structural inspections are often supplemented with testing and investigations to determine the cause, extent and severity of noted defects or deterioration on structures. There are many structural testing and investigation techniques currently available to engineers to examine and rapidly assess the cause, extent and severity of structural defects and to determine the overall condition of structures.

The range of testing and investigations available to Infrastruct as part of our Structural Inspections services are as follows:

Concrete Structures – Reinforcement Surveys Concrete Structures – Quality & Integrity Surveys Steel Structures – Testing Material Sampling for Analysis
Covermeter surveys Ultrasonic Pulse Velocity (UPV) testing Ultrasonic Thickness (UT) measurements Chloride content analysis
Ground Penetrating Radar (GPR) surveys Rebound Hammer testing Portable Hardness testing Carbonation depth testing
Half-Cell Potential surveys s’MASH Impulse Response testing Magnetic Particle Inspection (MPI) Cement content analysis
Linear Polarisation Resistance (LPR) measurements DOCter Impact Echo testing Sulphate content analysis
Resistivity surveys CTG2 Concrete Thickness measurement Alkali content analysis
Delamination (sounding) surveys:

  • Hammer tapping
  • Delam tool surveys
Crack Pattern and Analysis

  • Crack length
  • Crack depth
  • Crack width
Coring (75mm, 100mm & 150mm):

  • Compressive strength
  • Tensile Strength
  • Density
Targeted Breakouts MIRA Pulse Echo Thermography Petrographic examination
Permeability testing (site) Permeability testing (laboratory)