The Plate Load Test and is normally used to measure the short term settlement of pavement sub-grade, temporary works platforms or building footings under their proposed design load. The value of settlement against load is then used to check that the soil meets design load settlement criteria. The test therefore is of use to both contractors and to specifying authorities and is regarded as the ‘gold standard’ of insitu assessments.
The AX01 Plate Load Test is used to determine:
Load-settlement (deflection) curve
Strain moduli of the first and the second loading cycle, Ev1 and Ev2 (an indicator for the bearing capacity of the soil under the loading plate)
Modulus of subgrade reaction, ks (a measure of the stiffness)
Ratio Ev2/Ev1 (a figure for the compaction level)
Site characterisation is unarguably the most important, but also most “difficult”, component of geo-engineering. The AX01 Plate Load Test is designed to improve the quality of site characterisation and reduce the difficulties involved.
The advantages of the AX01 Plate Load Test include:
Measuring actual foundation performance:
Reduce construction risk as design assumptions / parameters are directly validated
Increase certainty of design assumptions (reduces the risk of over design and under design)
Potential to refine design parameters based on on-site measurements – potentially reducing capital cost
Faster
Short operation time (approx 25-30 mins per test including setup, test & results graphing), rather than 2-4 hours just to setup and do the test plus data analysis adding significant additional time
Provides immediate results so that on-site decisions can be made straight away.
Cost effective
One person operation
Improved safety
Safe operation as operator away from the counterweight and does not read dial gauges and record results whilst under the counterweight
Accurate and Repeatable
Results directly reflect insitu site conditions
Non destructive
Without errors
No further data analysis or calculations required – data is analysed electronically on the spot, saving significant time
Equipment is instrumented (data is automatically and accurately recorded)
Results are machine produced (overcoming manual data recording, transposition or calculation errors and fictitious results)
Improved data flow and integrity
GPS located and time stamped – know where and when every test is done
Visually presented results
Graphical representation of the data on the electronic box
Plate Load Test Applications
Applications for this non destructive plate bearing test method for measuring bearing capacity and compaction control include flexible pavements, unsealed roads and mine access roads, tunnels, railway track beds, airport runway and taxiways, hard standing areas, wind farms, building foundations, pipe laying and tank farms.
For example, the Plate Load Test is used to determine whether the ground has sufficient bearing capacity to support a given structure such as temporary pads for crane outriggers or piling rigs. It is very useful for mobile crane operators and piling rig contractors to check potential settlement of crane pads or mats under full load before the mobile crane or piling rig is sited or when traversing the site. The results of a Plate Load Test will enable you to calculate the size of outrigger spreader plates or mats required, and the ground movement that can be expected.
We also have clients who require bearing capacity data but no penetration is allowed because of services e.g. on railway trackbeds.
Clients include those involved in pavement construction, pavement rehabilitation, material testing, geotechnical testing and site investigation and include road authorities, councils, asset managers, mines, engineering and construction groups, mobile crane operators and piling rig contractors, geotechnical consultancies and research organisations.
The Plate Load Test AX01 is the simple solution to determine the strain moduli Ev2 and Ev1 (a figure for the bearing capacity) and the ratio Ev2/Ev1 (a figure for the compaction level). The modulus is an indicator for the bearing capacity of the soil or flexible pavement under the loading plate.
For the test, the soil is loaded and unloaded in fixed steps using a circular loading plate and a hydraulic loading device.
The load plate is loaded by a hydraulic jack and it’s settlement is measured at increasing load increments. During two loading cycles, different loads will be applied in steps to the loading plate using a hydraulic hand pump. For each loading step, the corresponding settlement (deflection) of the plate is recorded. The device is equipped with an electrical force sensor to record the load and an inductive displacement gauge to determine the deflection.
A graph is then plotted of settlement against bearing pressure and will show settlement at any given load. This information is used to calculate the Modulus of Subgrade Reaction, a measure of the stiffness of the subgrade known as the K value. It is expressed as load per unit area per unit of settlement e.g. KN/m2/mm or KPa/mm.
The results of the test are evaluated immediately, shown at the display, and printed with the built-in thermo printer at the road-works. The test results can also be stored on a memory chipcard. Using a chipcard reader, the results can be transferred into an MS Excel sheet on a Windows-PC for further analysis.
In order to perform this test, it is important to have sufficient kentledge to jack against. The counter weight could be equipment you have on site such as an excavator, roller or a truck loaded with material. The choice of plate size depends upon the required bearing pressure, depth of influence required and the available kentledge.
The AX01 Plate Load Test comes with a 300mm load plate as standard but 600mm and 762mm load plates are available. The equipment comes with a 20T hydraulic jack but a 10T jack option is also available. The maximum bearing capacities are as follows:
Best Practice in Compaction QA for Pavement and Subgrade Materials Year 1 Report Jeffrey Lee, David Lacey & Burk Look NACOE P60 QLD DTMR, Australia Aug 2017
Category: Research Papers
Topic: Comparative Studies – PANDA® vs other Compaction Control Methods, Comparative Studies between the Light Weight Defectometer and other Devices., Comparative Studies between the Plate Load Test (PLT) and other Devices
Relationship between surged reaction modulus and the strain modulus obtained using a plate loading test – High Speed Rail – Dae Sang Kim & Seong Yong Park
Category: Research Papers
Topic: Plate Load Test
Author: DaeSang Kim, SeongYong Park
Date: 2011
Plate loading tests (PLTs) have been used to evaluate the compaction quality of the railroad subgrade in Korea. Two methods to determine the design modulus are being used together; one is an unrepetitive plate loading test (uPLT) that obtains the subgrade reaction modulus (K30) and the other is a repetitive plate loading test (rPLT) (e.g. Anix AX01a) that obtains the strain modulus (Ev). There are some differences between the two methods, such as, the way in which the design modulus is evaluated, the number of loading steps, and the test procedures. Firstly, this paper compares the two test methods and summarizes the differences between them. Secondly, the relationship between the two moduli was obtained by using the results of 30 field tests of uPLT test and rPLT test carried out on the subgrade under railroad construction. The comparisons show that the two tests give large differences in stress-displacement relationship and that the correlations between the two moduli didn’t indicate a good relationship. Consequently, it was found that corrections of two the moduli for stress and strain level are needed to evaluate the relationship between the two moduli, because the stress and strain level are different when K30 and Ev2 are evaluated. Therefore, if the relationship between the two moduli is developed from the correction procedure, it will help field engineers in the management of compaction control for railway embankments.
NACOE Advanced Methods for Compaction Quality Control – June 2018 Webinar – Part 1 (Webinar Slides)
Category: Research Papers
Topic: Comparative Studies – PANDA® vs other Compaction Control Methods, Comparative Studies between the Light Weight Defectometer and other Devices., Comparative Studies between the Plate Load Test (PLT) and other Devices
Advanced Methods for Compaction Quality Control Part 2 Question Answers
Category: Research Papers
Topic: Comparative Studies – PANDA® vs other Compaction Control Methods, Comparative Studies between the Light Weight Defectometer and other Devices., Comparative Studies between the Plate Load Test (PLT) and other Devices
NACOE Advanced Methods for Compaction Quality Control June 2018 webinar part 2
Category: Research Papers
Topic: Comparative Studies – PANDA® vs other Compaction Control Methods, Comparative Studies between the Light Weight Defectometer and other Devices., Comparative Studies between the Plate Load Test (PLT) and other Devices
ASTM D1195 D1195M (2021) Standard Test Method for Repetitive Static Plate Tests of Soils and Flexible Pavement Components for Use in Evaluation and Design of Airport and Highway Pavements
Best Practice in Compaction QA for Pavement and Subgrade Materials NACOE P60 Year 3 Report Lee, Lacey, Look & Tarr June 2020
Category: Research Papers
Topic: Comparative Studies – PANDA® vs other Compaction Control Methods, Comparative Studies between the Light Weight Defectometer and other Devices., Comparative Studies between the Plate Load Test (PLT) and other Devices
Author: Jeffrey Lee, David Lacey, Burt Look, Kyle Tarr
Comparative Studies between the Plate Load Test (PLT) and other Devices
Best practice in compaction quality assurance for pavement and subgrade materials – National Asset Centre of Excellence (NACOE) – Queensland Department of Transport and Main Roads and the Australian Road Research Board (ARRB) – P60
The acceptance of earthwork and unbound pavement construction in Australia currently relies mostly on density testing and CBRs for Quality Assurance (QA).
Though its National Asset Centre of Excellence (NACoE) research program, Queensland’s Department of Transport & Main Roads sponsored a vital ARRB research project to update test methods acceptable for use for QA of pavement and subgrade materials. This state-of-the-industry study assessed test methods that have the potential to:
(a) reliably provide a direct measure of the strength or in-situ modulus value; and
(b) offer significant time savings in turnaround time of test results.
In earthworks testing, using density ratios is applied widely in quality control. There are currently many different measuring devices which can provide a more accurate measurement of design parameters (strength or stiffness) and can provide a more direct route for parameter assessment (i.e. limit need for any inclusion of generic relationships).
Comparisons of density with alternative in-situ testing show the latter provides significant benefits to the industry. Accuracy is not the same as precision, and industry’s reliance on density places an emphasis on precision rather than accuracy, data usability or timeliness of results.
This research has found density measurements are, although precise, not very accurate due to poor correlation with the results of other modulus or strength-based tests.
The most important Technical Standards for values required for the Deformation Modulus, in Germany, are:
“Zusätzliche Technische Vertragsbedingungen und Richtlinien für Erdarbeiten im Straßenbau” (Additional Technical Terms of Contract and Guidelines for Earthworks in Road Construction) ZTV E-StB 09,
“Zusätzliche Technische Vertragsbedingungen und Richtlinien für Aufgrabungen in Verkehrsflächen” (Additional Technical Terms of Contract and Guidelines for Excavations in Traffic Areas) ZTV A-StB 97/06
“Zusätzliche Technische Vertragsbedingungen und Richtlinien für den Bau von Schichten ohne Bindemittel im Straßenbau” (Additional Technical Terms of Contract and Guidelines for the Construction of Courses without Binder in Road Construction) ZTV SoB-StB 07.
In accordance with ZTV E-StB, quality control is carried out according to a statistical test plan. In this method, the statistical distribution of the inspection criterion being examined is determined within an inspection lot on a random sampling basis. The decision as to whether the inspection lot is accepted or rejected is made on the basis of the results of the random sampling.
This method can be applied to any kind of ground.
The application of this method is particularly advisable in the following cases:
with large inspection lots
with inspection lots for which the uniformity of the compaction is to be evaluated
with inspection lots on which test procedures requiring little time are used and whose results are available immediately
The statistical method should also be used for sample compactions.
In the statistical method, one inspection lot is assessed each time. An inspection lot is a layer of compacted ground that has been processed under uniform conditions and for which there is a uniform requirement. The area of the inspection lot should be precisely specified.
The test is carried out on a random sampling basis in which the position of the test points in the testing area is to be determined by means of a random selection process. The scale of the random sampling (n) depends on the size of the inspection lot.
The arithmetic average ( ) and the standard deviation (s) are calculated on the basis of the results (xi) of the random sample.
In the case of a 10% minimum quantile TM (degree of compaction, deformation modulus), the quality number Q is generated on the basis of and s (3).
At the acceptance of the construction work, the inspection lot will be accepted if Q≥k, where k is the acceptability constant in accordance with Table 1; otherwise the inspection lot will be rejected. It must then be brought into a condition that meets the requirements by the contractor. In the case of a rejection, the entire area of the inspection lot must be rejected.
Table 1: Scale of random sampling and acceptability constant for a single plan for the inspection of variables depending on the size of the inspection lot
Size of inspection lot
Area [m²]
Length of utility trench
Length per m of trench depth
Scale of random sampling n
Acceptability constant k
up to 1000
over 1000 to 2000
over 2000 to 3000
over 3000 to 4000
over 4000 to 5000
over 5000 to 6000
up to 100
over 100 to 200
over 200 to 300
over 300 to 400
over 400 to 500
over 500 to 600
4
5
6
7
8
9
0.88
0.88
0.88
0.88
0.88
0.88
The requirements mentioned below refer to the 10% minimum quantile TM in accordance with ZTV E-StB.
In the case of a road surface for heavy to medium traffic on a frost-proof subgrade or subbase, a deformation modulus of at least Ev2 = 120 MN/m² is required on the formation level. For light traffic, a deformation modulus of at least Ev2 = 100 MN/m² is required.
In the case of a frost-susceptible subgrade or subbase, a deformation modulus of at least Ev2 = 45 MN/m² must be proven on the formation level.
In the case of a frost-susceptible subgrade or subbase, Ev2 ≥ 70 MN/m² must be the case on the formation level after professional soil improvement has been carried out.
In accordance with ZTV E-StB, the static plate loading test can be used as a substitute for determining the degree of compaction in accordance with Table 2 for coarse-grained soils and mixed-grained soils with a fine grain proportion of less than 15 % (m/m).
For allocation to the degree of compaction, the deformation modulus Ev2 must adhere to the lower limit given in Table 2, while the ratio Ev2/Ev1 must adhere to the upper limit given in Table 2.
If the Ev1 value has already reached 60% of the Ev2 value given in Table 2, higher Ev2/Ev1 ratios are also permitted.
Table 2: Standard values for allocation of the static deformation modulus Ev2 and the ratio Ev2/Ev1 to the degree of compaction DPr for coarse-grained soils
Soil group
Static deformation modulus Ev2 [MN/m²]
Ratio
Ev2/Ev1
Degree of compaction Dpr [%]
GW, GI
≥100
≥80
≤2.3
≤2.5
≥100
≥98
GE, SE, SW, SI
≥80
≥70
≤2.3
≤2.5
≥100
≥98
For base courses without binder, the following applies in accordance with SoB-StB:
In the case of roads of German construction classes SV, I to IV, on a formation level with Ev2 ≥ 45 MN/m² a deformation modulus of Ev2 ≥ 120 MN/m² must be achieved on the frost protection layer.
On roads of German construction classes V and VI, the required value is Ev2 ≥ 100 MN/m.
On gravel and crushed stone base courses, the ratio of the deformation moduli Ev2/Ev1 must not be greater than 2.2 if a degree of compaction DPr ≥ 103 % is stipulated. With a degree of compaction DPr < 103 %, Ev2/Ev1 must be ≤ 2.5.
Ev2/Ev1 ratios higher than 2.2 or 2.5 are permitted if the Ev1 value is at least 0.6 times the required Ev2 value.
In the case of roads of German construction classes SV, I to IV the following deformation modulus Ev2 must be achieved on frost protection layers with Ev2 ³ 120 MN/m² depending on the thickness of the base course without binder:
on gravel base courses: ≥20 cm: Ev2 ≥150 MN/m² and ≥25 cm: Ev2 ≥180 MN/m²
on crushed stone base courses: ≥15 cm: Ev2 ≥150 MN/m² and ≥20 cm: Ev2 ≥ 180 MN/m²
In the case of roads of German construction classes V and VI, the following deformation modulus Ev2 must be achieved on frost protection layers with Ev2 ≥ 100 MN/m² depending on the thickness of the base course without binder:
on gravel base courses: ≥20 cm: E v2 ≥120 MN/m² and ≥25 cm: E v2 ≥ 150 MN/m²
on crushed stone base courses: ≥15 cm: E v2 ≥120 MN/m² and ≥20 cm: E v2 ≥150 MN/m²
Unlike with ZTV E-StB, these required values are not the 10% quantile but rather minimum values for which deviations should be evaluated as follows:
With fewer than five individual values, each of the individual values must be equal to or exceed the required minimum values.
With five or more individual values per inspection lot, one individual value in each case may fall below the required minimum value for the deformation modulus by no more than 10%.
The permitted deviations only apply, however, if these individual values relate to the five measurement locations that are closest to each other in each case.
Other supported standards include:
DIN 18134:2012-04, Baugrund – Versuche und Versuchsgeräte – Plattendruckversuch, Deutschen Institut für Normung (Germany) – describes how to set up and carry out the plate loading test
CNR BU 146 1992-12, determinazione del MODULO DI DEFORMAZIONE, Consiglio Nazionale delle Ricerche (Italy)
ÖNORM B4417:1979-12, Erd- und Grundbau; Untersuchung von Böden; Lastplattenversuch, Austrian Standards Institute (Austria)
SN 670 317b:1998, Plattendruckversuch, Norme Suisse (Switzerland)
TSC 06.720:2003, MERITVE IN PREISKAVE – DEFORMACIJSKI MODULI VGRAJENIH MATERIALOV, REPUBLIKA SLOVENIJA (Slovenia)
NF P94-117-1:2000-04, Portance des plates formes – Module sous chargement statique à la plaque, Norme française (France)
BS 1377 Part 9:1990-08 Methods for test for soils for civil engineering purposes. In-situ tests, British Standards + HD 25 PAVEMENT FOUNDATIONS (UK)
UNE 103808:2006-02, Ensayo de placa de carga, Asociación Española de Normalización y Certificación (Spain)
We are pleased to let you know that the AX01 Plate Load Test is now compliant with the ASTM International standards. The Plate Load Test is normally used to measure the short-term settlement of pavement sub-grade, temporary works platforms, or building footings under their proposed design load. ASTM D1195 covers the apparatus and procedure for […]
We find clients are often looking for ways to improve geotechnical testing outcomes and do it more efficiently at the same time. This drives their buying decision making. Australian Soil and Concrete Testing (ASCT) was a case in point when they were searching for Plate Load Test equipment for their upcoming Collector Wind Farm project. Some of the things that motivated them include: […]
We find our clients are increasingly demanding more accurate and more representative results that provide better insight on what’s going on below the surface when they are designing or constructing projects so they can make well-informed decisions in a timely manner. Having worked for nearly 15 years at the forward edge of field-testing methods that […]
The Plate Load Test is an excellent insitu site investigation field test used to determine the ultimate bearing capacity of the ground and the likely settlement under a given load. It is designing for measuring static loads on spread footings (e.g. to determine whether the ground has sufficient bearing capacity to support structures like wind […]
One of the key concerns of project managers is safety, including the risk of people getting injured or killed at site. Hence, for temporary working platforms, the need to measure the in-situ bearing capacity to minimise the risk of a critical failure or incident for mobile crane / temporary cranes applications, piling rig and heavy […]
The AX01 is supplied with a 10 Tonnes capacity jack but a jack with 20 Tonnes capacity is also available.
Ev1 – static deformation modulus or strain modulus of the first loading cycle for the bearing capacity
Ev2 – static deformation modulus or strain modulus of the second loading cycle for the bearing capacity
The ratio Ev2/Ev1 is a figure for the compaction level
Ev2 and Evd relationship – the relationship between the strain modulus Ev2, measured by the static plate load test, and the dynamic deformation modulus Evd depends on the kind of soil and the degree of compaction.
Experience shows that the ratio Ev2/Evd lies in the range 1.0 to 4.
For densely compacted soils Ev2/Evd ~ 2.3
On average the following relation between the dynamic deformation modulus Evd, and the strain modulus Ev2, can be used:
This relation does not hold for limiting values.
What is the AX01 plate diameter?
The AX01 is supplied with a 300mm plate but 600mm and 762mm plates are also available.
What other names is the Plate Load Test known by?
Static load plate bearing tester
Static plate bearing test
Plate bearing test
Plate bearing tester
Static plate test
Static plate bearing test
Static plate load test
AX01
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