Contents

Overview

• The default method in QESTLab for determining the density of hardened concrete is the density by measurement method.
• The alternative method for determining the density of hardened concrete, by using the displacement of water method, is also supported by QESTLab.
• The density by water displacement method is of particular use when test specimens do not have smooth surfaces or regular shapes.

Introduction

• In QESTLab, only whole samples can be marked for density testing by water displacement, not individual specimens.

• The requirement for determining of density by water displacement has to be set on the Concrete Sample (AU) screen.
• This can be done at any time, but is probably best done as part of the sample and test registration process.
• Full data entry can be carried out on the Concrete Sample (AU) screen and EWS but not QWS.

Setting Up for Density Testing by Water Displacement

Test Registration

Registering a sample for density testing by displacement is carried out by ticking the Density by Water Displacement checkbox in the Density by Displacement frame of the Concrete Sample (AU) screen.

Moisture Condition of Density Test

• It is generally accepted that the density (mass per unit volume) of concrete may be determined in any moisture condition, as long as it is reported appropriately.
• The moisture condition to be adopted should be specified when the specimens are submitted for test.
• QESTLab provides the Condition dropdown in the Laboratory frame, on the Concrete Sample (AU) screen, to record the moisture condition required for testing.

Concrete Sample (AU) screen

Specimens without Steel Reinforcement

The following example is from a COMP100 specimen type but other specimen types will exhibit similar behaviours.

When a specimen is selected for data entry, the following fields are changed or added to the specimen test grid if density by displacement has been indicated for the sample.

For details of the other fields in the specimen grid, refer to the Concrete Sample (AU) screen,

Example

COMP100 tested in saturated surface-dry state.

Specimens with Steel Reinforcement

If the steel can be removed without serious damage to the specimen, it should be.

1. The remaining void should not be filled but the edges can be patched/dressed if required.
2. The density determination can then proceed as for specimens without steel reinforcement present (above).

If the steel cannot be removed without serious damage to the specimen, the Concrete Sample (AU) screen's specimen test grid provides a method for correcting density results for the presence of steel reinforcement in a specimen.

• Carry out the density procedure with the specimen as if no steel was present.
• After the density results are recorded, remove and collect all the steel from the specimen.

When the Dressing of Voids checkbox is ticked for core specimen types, the following fields will be available, in addition to the above fields.

When these values are entered for the specimen, the density results will be corrected to account for the presence of steel reinforcing in the original results.

Example

COMPCOR, with steel reinforcing, tested in saturated surface-dry state.

Electronic Worksheet (EWS)

• The electronic worksheet for concrete specimens works exactly the same as the Concrete Sample (AU) when determining the density of hardened concrete by water displacement.
• However, before the EWS can be used for this test method, the above 2248868274 must be applied via the Concrete Sample (AU) screen.
• For information on accessing, and data entry to, the EWS, refer to Using the Electronic Worksheet.

QEST Weigh and Measure Station (QWS)

• The QWS for concrete specimen test grid appears to be the same as the Concrete Sample (AU) when determining the density of hardened concrete by water displacement.
• As for the EWS, before the QWS can be used for this test method, the above 2248868274 must be applied via the Concrete Sample (AU) screen.
• For information on accessing, and data entry to, the QWS, refer to Using the QEST Weigh and Measure Station

If the QWS is used for a specimen requiring density by water displacement, the weight measured is the Rec Wt,.

The remaining two required values, Imm Wt and ssd Wt, cannot be entered through QWS and need to be entered through the Concrete Sample (AU) screen or the EWS, to complete the test.

Additionally, for specimens containing reinforcing steel, the values required for the density correction for the presence steel cannot be entered through QWS and an alternative data entry pathway (as above) is required.

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