SPECIFICATIONS FOR A FULLY AUTOMATED, COMPUTER CONTROLLED RESILIENT MODULUS, TRIAXIAL AND UNCONFINED COMPRESSIVE STRENGTH (RMTUC) TESTING SYSTEM ON SOILS AND AGGREGATE MATERIALS
1. General System, Equipment and operational Requirements
Equipment must consist of a fully operational and functional system (including all necessary sample preparation and testing components) meeting the following requirements:
1.1 One (1) new and complete computer controlled, fully automated Resilient Modulus, Triaxial and Unconfined Compressive Strength Soil Testing System, ready for immediate operation with all hardware and software components (i.e. load frame, control and data acquisition software, and related computer interface hardware and manuals, editing and reporting software and manuals, sensors, connection cabling, etc.). The apparatus and software must be configured such that, at a minimum, it is capable of testing undisturbed and disturbed compacted samples of subgrade soils, and untreated base/subbase compacted to various diameters not to exceed 6.0 in. (152 mm), and with a height to diameter ratio of at least 2-2.5:1 including the following standard sizes:
a. Standard "thin wall type" (2.875 in [71 mm] diameter), height to diameter ratio of 2V:1H to 2.5V:1H specimen.
b. Standard recompacted sample (4.00 in [100 mm] diameter), height to diameter ratio of 2V:1H to 2.5V:1H, specimen.
c. Standard recompacted sample (6.00 in [152 mm] diameter) height to diameter ratio of 2V:1H to 2.5V:1H, specimen.
1.2 Confining pressure application, to be done automatically through an electro-pneumatic system, according to default, preset or operator defined pressures and pressure application rates and durations for Resilient Modulus testing.
At the operator’s option, the confining pressure must either be applied automatically according to preset standard or standard default settings in compliance with the Triaxial test methods listed in Section 2.1.1 of this document, or according to operator defined pressures and application rates and durations. Confining pressure must be fully controlled and maintained by system hardware and software.
1.3 Include comprehensive manuals for Resilient Modulus, Triaxial and Unconfined Compressive Strength editing and reporting software, equipment operation and maintenance. Manuals must thoroughly describe the capabilities, function, set-up, calibration and control of all equipment and software, including troubleshooting and maintenance of all systems (equipment and software).
1.4 Software is to be coded onto a separate computer, not into the testing system. Software must provide the functionality as described in paragraph No. 1. Software must be compatible with Windows 7 Enterprise (64 bit) and Windows 10 Enterprise (64 bit) operating systems.
1.5 All sensors and instrumentation required to perform, monitor and acquire data for the test methods specified in Section 2.1.1 of this document.
1.6 Related data acquisition equipment, computer interfaces, and connection cabling.
1.7 Any and all equipment necessary for preparing each sample for all test methods specified in Section 2.1.1 of this document (at a minimum for 71 mm, 100 mm and 152 mm diameter samples) for testing.
1.8 The system must be configured in both hardware and software such that it meets the rigid AASHTO T-307, RD02-034 and LTPP Protocol P46 specifications for precision on loading through all stages of the test without requiring manual adjustment during the test.
1.9 As illustrated in Figure 1 below, this test protocol requires the load to be applied and removed in 0.1 sec according to a haversine shape, followed by a 0.9 second rest period.
Fig 1. Haversine LTPP Protocol on loading
1.10 The system must shear a sample keeping a constant rate of strain using a high precision electro-mechanical controller. Vertical cyclic loading must be done through a high precision electro-mechanical load actuator.
1.11 On-site training, installation, documentation, and comprehensive minimum one year (after date of system acceptance – installation, set-up and calibration complete, training complete, and all systems demonstrated to be in full properly working order) hardware and software systems parts and repair warranties are to be included as part of this package. Refer to these sections in this document for further description.
1.12 One (1) computer running Windows 7 Enterprise (64 Bit) operating system that automatically controls and acquires data for all test methods listed in Section 2.1.1 of this document, as well as perform all data reduction and reporting operations. Data must be stored in a format that is operator editable in the event of run-time test problems that result in invalid data.
2. SYSTEM REQUIREMENTS
The computer processor, monitor and computer peripherals (i.e. pointing devices, keyboard, display, printers, uninterruptable power supplies must be supplied by the successful bidder. The successful bidder must provide appropriate data acquisition (D/A) cards/devices and software.
Data acquisition must have a minimum 16 bits of resolution with dedicated channels for each sensor. Multiplexers are not permitted.
Any necessary I/O cards to accept or transmit information from/to data acquisition systems, signal processors, control devices, etc. must be included as must all relevant sensors, controllers, load frames, related attachments and fittings, wiring, tubing, valves, and related computer software to control test function, acquire data, perform test calculations (with the exception of those requiring significant engineering judgment), and output data and graphical displays both to the screen and printed output.
The computer processor must be provided by the successful bidder, and must run under Windows 7 Enterprise (64 Bit) and Windows 10 Enterprise (64 bit) operating systems. Hardware and software must be compatible with this environment.
2.1 Equipment Requirements
2.1.1 Equipment for the testing system must be consistent with standard sizes and methodologies used in performing standard AASHTO and ASTM test methods, including:
a. "Determining the Resilient Modulus of Soils and Aggregate Materials", AASHTO Designation: T 307-99(2012) and SHRP Protocol P46.
b. “Standard Test Method for Consolidated Undrained Triaxial Compression Test for Cohesive Soils”, ASTM Designation D4767-11.
c. “Standard Test Method for Consolidated Drained Triaxial Compression Test for Cohesive Soils”, ASTM Designation D7181-11.
d. “Standard Method of Test for Unconsolidated, Undrained Compressive Strength of Cohesive Soils in Triaxial Compression”, AASHTO Designation T 296-10
e. Standard Test Method for Unconfined Compressive Strength of Cohesive Soil”, AASHTO Designation T 208-15.
2.1.2 The system must operate on standard 120V or 220V 60 Hz power.
2.1.3 The system must be appropriately rugged to withstand a standard laboratory testing environment with a projected service life of 10 to 15 years.
2.1.4 The system must be designed to operate at a standard room temperature environment of 10⁰C to 32⁰C (50⁰F to 90⁰F). The equipment must be able to withstand temperatures of -12⁰C to 49⁰C (10⁰F to 120⁰F) for shipping and storage.
2.1.5 The system must use shielded electrical cables to reduce signal noise and interference that may otherwise result in undesirable effects.
2.1.6 The unit must come equipped with all standard equipment pertinent to the test methods listed in Section 2.1.1 of this document including, but not limited to, test cells, platens, gaskets, locking screws, fittings, valves, tubing, sensors, membranes and "O" type rings, and sensor mounting assemblies.
2.1.7 The system must include all standard equipment required to prepare test specimens for the test methods listed in Section 2.1.1 of these specifications, and of the size and dimensions as indicated in Section 1 of these specifications.
2.1.8 A compressor must be provided having a minimum rated operating pressure, not maximum or peak pressure, meeting the required operating pressure for all tests methods in Section 2.1.1 of these specifications, along with all necessary tools, fittings and equipment to connect to the air compressor to the test system.
2.1.9 The electro-mechanical load actuator must include the following:
a. One (1) Automated load frame with the following technical specifications:
· 10,000 lbf (45 kN) load capacity
· 500 lbf (2.22 kN), 2000 lbf (8.90 kN) and 5000 lbf (22.2 kN) external load cells. Other load cell capacities up to 10,000 lbf (4.45 kN) must be easily interchangeable.
· Embedded controller
· Dedicated channels with signal conditioning and power supplies built-in. Sufficient dedicated channels must be provided to run all tests indicated in these specifications.
· Built-in Data Acquisition and Control
· Front panel LCD and Keypad for manual controls
· Variable Speed range to run all tests indicated in these specifications to the requirements of the individual test methods indicated.
· Accommodates test cell up to a max. Diameter of 6.00 in. (152 mm)
· Platen travel = min distance required to perform all tests in Section 2.1.1
· Upper and lower limit switches to prevent ram over travel
· Built-in software safety shut-off when sensors max out
· Uprights with quick release/removal for easy and fast movement of cross head
· Remote network access, monitoring, and control
· Sensors set-up and configuration via software
· Integrated control and data acquisition board
b. Electro-mechanical linear actuator that applies load pulses meeting the requirements of all indicated test methods in Section 2.1.1 of this document.
c. Electro-Pneumatic Cell Pressure Controller including mounting bracket, fittings, mist separator filter and particle separator filter, and built-in pressure sensor with digital display for the Resilient Modulus test.
d. Automatic pressure and vacuum controllers (for cell, pore and back pressures, etc.), including all necessary equipment and accessories. Integral pressure sensors with digital displays meeting the requirements for all triaxial test methods listed in Section 2.1.1 of this document. All pressures must be fully controlled by system software.
e. Automatic volume change measurement, monitoring and recording device for all the triaxial test methods listed in Section 2.1.1. (Volume change must not be determined manually.)
2.2 Test Control Requirements
2.2.1 The hardware and software components must allow full operation and control of the testing system, including permitting fully automated operation of the equipment, permitting alternate manual inputs and control of all loads, load rates and frequencies, strain rates, and measurement sampling and recording frequencies of all measurement and monitoring instruments/sensors, and provided real time numeric and graphical monitoring of all system functions, loadings and load rates, and monitoring instruments/sensors.
The hardware and software must provide both fully automated and operator defined modes of observation, recording and transfer all of test parameters and data, and instrument/sensor recordings. The test apparatus must be configured to be both computer controlled, and operate as a standalone unit with manual controls on the front panels of the load frame with keypads and LCDs. The load frame must be able to have loads applied and removed, at the rates, magnitudes and shapes required, by the computer control system. Loading rates must have the option of being specified and controlled by the computer, or via manual override. The computer interface must allow the operator to adjust calibration factors and the rate of data acquisition.
The equipment must include an internal automated controller, but permit manual override and direction to the internal controller from the external computer interface. The external computer interface must acquire real time operational data and transfer all data and load/strain curves for the completed tests directly from the equipment’s internal controller.
The apparatus must have necessary control functions to allow the operator to manipulate the location of the load platen for functions such as resetting the apparatus for a new test.
2.2.2 Vertical forces/displacements must be applied with high precision electro-mechanical load actuators for the tests specified in Section 2.1.1 of this document at appropriate rates and within specified tolerances, consistent with those indicated in the relevant AASTHO/ASTM specifications. Vertical displacements must be able to be applied at strain rates ranging from 0.3%/min to 1.0 %/min (as slow as 0.000001 in/min [0.00003 mm/min] and at least 0.6in/min [15 mm/min], though the maximum may exceed this value) for the Resilient Modulus test. Vertical displacements must be able to be applied at axial strain rates ranging from 0.5%/min to 2%/min for Unconfined Compressive Strength tests. Pneumatic, hydraulic loading systems or other systems for the application of vertical loads, other than indicated in these specifications, are not permitted.
Vertical loads and displacements must be monitored by appropriate sensors that transmit the information to the data acquisition system for use in engineering calculations and real time display and recording of load, displacement, and applied stresses/strains.
2.2.3 Test control parameters (applied loads and/or displacement rates and end of test criteria) must be adjustable during the testing sequence. The test control software must allow the test to be aborted at any time without the loss of existing data. Sensors must be included to detect an overload or ‘out-of-range’ condition and system controls must terminate the test if such conditions occur in order to protect the test system.
2.2.4 Readings, in operator defined or selected units, must be displayed in real time from test sensors to monitor the test and computer control system.
2.2.5 Sensor readings must be able to be electronically "zeroed" in the test control program.
2.3 Tolerance Requirements
2.3.1 Vertical displacements must be able to be determined to a minimum precision of .0001 in (.0025 mm) for the Resilient Modulus System. The Resilient Modulus System measuring device(s) for axial deformation must have a minimum range of:
Specimen Diameter / Range(mm) / (mm) / (inch)
71 / 1 / 0.04
100 / 2.5 / 0.1
152 / 6 / 0.236
The requirements in the above table for range are approximately linear when plotted versus specimen cross-sectional area. Requirements for the measuring devices for axial deformation used with other specimen diameters must be approximated linearly.
The Vertical displacements must be able to be determined to the minimum range and precision requirements in the Triaxial and Unconfined Compressive Strength test methods specified in Section 2.1.1 of this document.
2.3.2 Vertical loading must be maintained for the duration of appropriate testing periods (at each increment). The following capacities and accuracies are required for the axial load-measuring devices for the Resilient Modulus Test:
Specimen Diameter / Max Load Capacity / Required Accuracy(mm) / (kN) / (N)
71 / 2.2 / 4.5
100 / 8.0 / 10.0
152 / 22.24 / 22.24
The above requirements for load capacity and accuracy are approximately linear when plotted versus specimen cross-sectional area. Requirements for load cells used with other specimen diameters must be approximated linearly. The accuracies are to be over the range of the applied load.