Viscosity Testing

2.6.2.3

Viscosity Testing

(1) The equipment needed to measure grout viscosity includes a

Marsh Flow Cone, a 1,000 mL 0.25 gal glass or clear plastic

graduated cylinder beaker, a 1,500 mL 0.38 gal (approximately)

empty beaker or bucket, and a stopwatch.

(2) Immediately after mixing the grout, transfer the grout from

the mixing bowl to the empty beaker or bucket. Take note of any

lumps of material or excess sand in the bottom of the mixing bowl.

Excess lumps indicate inadequate mixing and render the grout

useless for viscosity testing. Immediately fill the Marsh Flow

Cone with about 1,100 mL 0.28 gal of grout. A consistent head of

grout in the flow cone is achieved for all viscosity tests by

marking an 1,100 mL 0.28 gal fill line inside the flow cone. The

flow cone outlet is plugged by simply placing one's finger over

the outlet opening. Immediately after the flow cone is filled to

the 1,100 mL 0.28 gal fill line, position the cone over the 1,000

mL 0.25 gal graduated beaker. Release the grout opening and start

the stopwatch timer simultaneously. Measure the time of flow for

1 L 0.25 gal of grout from the flow cone to the nearest tenth of a

second.

(3) Record each test sample's viscosity, averaging the two

replicates for each blend. Adjust the grout mix proportions as

needed with the following considerations:

(a) Any grout viscosity between 8.0 and 10.0 seconds is

acceptable. It should be noted; however, that when field

construction temperatures are expected to be comparatively high

(greater than 32C 90F) and/or the open-graded asphalt concrete

voids are expected to be considerably low (less than 30 percent),

then lower viscosity grouts will help to ensure easy grout

application and full grout penetration. In most cases, these

variables are unknown; therefore, it is prudent to select the

grout formulation which has the lowest viscosity.

(b) Select a grout job-mix formula with water and resin

additive contents below the maximum allowable limits to allow the

Contracting Officer Representative to approve small additions of

these ingredients in the field if necessary to meet viscosity

requirements.

(c) Low w/c ratios shall be selected, within the viscosity

criteria, to produce grout with higher strengths; reduce the

chances for drying shrinkage cracking; and produce grout which is

more consistent and better able to keep the sand in suspension

during mixing and placement.

(d) When the sand is noted to settle out of solution during or

immediately after mixing, the JMF shall be adjusted by reducing

the amount of sand and increasing the amount of fly ash (both

within the specified tolerances).

(e) If the viscosity

requirements cannot be met, the Contractor

shall change the source

of materials. Typical problems to

investigate include the

following: grout sand which is too

coarse, portland cement

which is highly reactive during the early

stages of the hydration

process, fly ash with excess cementitious

SECTION 02746

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