G1+ Gauge

Table of contents

Technical characteristics
How to fix the gauge?
Installation tips
How to measure crack in angle?
Why and how to protect the gauge?
How to read the gauge with digital read out? 
How to monitor and save the data?
Related products

Technical characteristics

How to fix the gauge?

In order to most effectively measure the evolution of the crack, the gauge is usually attached at the widest point of the crack or in the middle of the crack. The G1+ gauge is made of a material that is flexible enough to accommodate and follow the movement of irregular, convex or concave surfaces.

There are two possible methods of fixing:

• By gluing: the fixing is ensured in a simple and fast way by double-sided self-adhesives supplied. The surface must be in good condition (it must not crumble), it must be relatively smooth so that the sticker can be stuck to the entire surface, it must be clean (free of dust and grease) and it must be dry.
  If necessary, and especially if the surface is not completely flat and has roughness, it is possible to reinforce the bonding with a fast-curing epoxy adhesive in a biseringue.
• Mechanical fixing: G1+ gauges are supplied with 2 holes of Ø 4 mm. These holes facilitate mechanical fastening by means of a impact anchors. The 4mm diameter makes it very easy to make the hole on any support.
  The screw + dowel set = Ø 4 mm : it is therefore sufficient to make 2 holes of Ø 4 mm, to place the impact anchor in the hole of the gauge and the folding bar, and to give a light hammer blow to fix the whole.
  On difficult substrates (crumbling, dusty, rough, damp), we recommend using impact anchors to prevent peeling off. Packs of 50 impact anchors are available or a complete ready-to-use impact anchors kit is available with a 4mm drill bit, a screwdriver and 30 impact anchors.

Result of fixing with anchors and screws:

Installation tips

Ideally, position the vernier triangle between 33 and 34 with the two speckled bands appearing on the right and left. The objective is to centre the pull tab. The principle consists in measuring the difference between 2 measurements: it does not matter the value of the first measurement, it is it which will constitute the 0 point.

Position the pin of the folding bar in the middle of the slotted hold to absorb any movement.
This patented system avoids straining the gauge by blocking the pull tab if there is also Y-axis movement.
However, this gauge does not measure Y-axis movement, so a G6 gauge must be used to measure movement on two axes of the plane.

How to measure the crack evolution in a vertical or horizontal internal angle?

It is possible to fix the gauge in angle : G1 family gauges are supplied with a foldable plastic angle bar.

Why and how to protect the gauges?

We recommend that gauges used in public places (schools, shops, streets) should be protected.
The protective cover can also be fixed with plugs and screws. Two types of protection are available: standard protection et high protection anti-UV.

How to read the G1+ gauge ?

The major innovation provided by the G1+ gauge resides in its “digital” readout of tenths of mm: indeed, each 1/10 mm movement of the pull tab causes the concomitant obstruction of a row of 6 white lights placed on this same tab. Each row is assigned to a digit (0 to 9) corresponding to the tenths of mm.

G1+ gauge reading at D day The mark on the vernier is located between 34 and 35 a) Reading the mm The number of mm corresponds to the graduation to the left of the mark on the vernier:  34 in the example shown b) Reading the decimal Identify the obstructed row(s). In this example, rows 1 and 2 are obstructed, meaning that the mark on the vernier is mid-way between the first and second tenth. The reading is thus neither 34.10 mm, nor 34.20 mm but 34.15 mm

Reading of the same G1+ gauge at D+90 days The mark on the vernier is located between 34 and 35 a) Reading the mm The number of mm corresponds to the graduation to the left of the  mark on the vernier: 34 in the example shown b)  Reading the decimal Identify the obstructed row(s) (black rows). In this example, only row 7 is black, meaning that the mark on the vernier is positioned exactly on the seventh tenth. The reading is thus 34.70 mm.

By subtracting the first from the second reading, we can infer that the crack has grown by 0.55 mm in a little more than 3 months.

The vernier, located on the top of the pull tab, will confirm these results if necessary (for instructions on reading the vernier, see the G1 gauge product sheet)

How to monitor and save data using the Excel file?

In order to facilitate the monitoring of the evolution of the cracks, you can download the Excel file for monitoring the G1+ measurements

This Excel file is very easy to use: you just have to duplicate a sheet for each site or construction site observed with the possibility to follow up to 10 gauges.
This file takes into account the coefficient of expansion of the gauge by adjusting each measurement taken with the temperature compared to the initial temperature of the 1st measurement. If you have not taken a temperature reading, simply leave it blank and the coefficient of expansion will not be taken into account.

Note that the impact of the expansion coefficient on the G1 gauge measurement is very small (about 9 micrometers every 1°C).

Here is an example of the type of monitoring obtained with the file: