This is one of our learning modules for UHPC Concrete. A new version will be released this year. We use such modules for training purposes. New ones are added every year. This year there will be four new modules. You want to check your answers for correctness? Send us an email service@hhbc-consulting.de with the password "LMS 1/6" and we will send you an answer sheet.
Module no. 1/6
What
are the main components in UHPC?
Cement,
microsilica, superplastisizer
Cement,
flyash, superplastisizer
Epoxy,
microsilica, dispersant
Cement,
sand, epoxy
Cement,
sand, microsilica
Acid
will deteriorate UHPC
True
False
Only
if pH is below 5
Only
if pH is above 5
Only
if pH is below 3
Alkali
will deteriorate UHPC
True
False
Only
if pH is above 12
Only
if pH is below 12
Only
if pH is above 13
The
following aggregates are used in UHPC Standard wear protection?
Quarz
Bauxite
Corundum
Silicium
carbide
Titanium
carbide
The
wear resistanse of UHPC increases with these aggregates?
Quarz,
bauxite, corundum, silicium carbide
Bauxite,
quarz, corundum, silicium carbide
Silicium
carbide, bauxite, quarz, corundum
Bauxite,
corundum, quarz, silicium carbide
Silicium
carbide, corundum, bauxite, quarz
What
is the lowest temperature at which it is ok to install UHPC?
20°C / 68°F
10°C / 50°F
5°C / 41°F
0°C / 32°F
- 5°C / 23°F
What
do you need to protect UHPC against when installing it?
Drying
out
Freezing
Wind
Direct
sun
Rain
What
should you focus on when mixing UHPC in regards to water?
The
product cannot seggregate
The
product must remain dry
There
must be free water on top of the product in the mixer
You
cannot add too much water to UHPC
Any
mixing problem can be solved by adding more water
You
notice lumps in a bag of UHPC Binder, what do you do?
No
problem, I just add more water when mixing
I
contact hhbc-consulting or to have a new bag
I
control the storage environment
I
discard the bag
I
check the date on the bag to see age of product
When
mixing UHPC lumps are formed shortly after adding of water?
No
problem, I just add more water
I
wait a while to see if they mix out, if not I will add a little more
water
I
throw away the mix
I
check if the mixer is proper prepared for mixing UHPC
I
increase the speed of the mixer
When
mixing UHPC I notice free water on the surface of the mix?
No
problem, Just need to use the product fast
I
allow the mixer to run for longer time, untill the free water is no
longer there
I
will try to scoop out the free water
I
throw away the mix
I
add more powder untill the free water disappeares
What
is the purpose of Microsilica in UHPC?
It
is packing between cement particles, increasing density and
displacing water
It
is like little ball bearings making the mortar more flowable
It
reacts with Ca(OH)2 from the cement hydration and create a denser
material
It
has no significant effect, just a filler to make the product cheaper
There
is no microsilica in UHPC
What
is the purpose of superplasticizer in UHPC?
It
makes the product more flexible
It
charges all particles so that they repell each other. At the same
time it makes stearic hinderence so that particles cannot bridge
build on each other, and in this way it displaces water.
There
is no superplasticizer in UHPC
It
is a polymer, added to make the product easier to mix
It
is lubricating the particles so that they can react better
UHPC
Binder can be installed over head?
True
False
Sometimes
if you are lucky
Only
during the weekend
Only
if you use a special throwel
HT
products can be used in temperature areas of
Up
to 1200°C / 2192°F
Not
above 1000°C / 1832°F
Not
above 600°C / 1112°F
Not
above 400°C / 752°F
Not
above 200°C / 392°F
UHPC
(not HT) can be used in temperature areas of
Up
to 1200°C / 2192°F
Not
above 1000°C / 1832°F
Not
above 600°C / 1112°F
Not
above 400°C / 752°F
Not
above 200°C / 392°F
It is
important to know what chemicals UHPC will be subjected to
True
False
Only
acid or alkalies
Especially
if there are salts present
Only
if temperature is above 100 deg C
When
mixing you notice the wetting time is increased. What do you do?
No
problem, I just add more water
I
wait it out for a while to see if it wets through, and I adjust the
water accordingly
I
throw away the mix
I
ignore it
Cross
my fingers and hope everything will be ok
What
happens to UHPC if too much water is added?
Nothing,
you can add as much water as you like
The
product will most likely seggregate, but properties will in general
be reduced in direct correlation with the amount of water added.
Especially
if we are working with a UHPC Cast product, installation will be a
lot easier
Strength
will increase as we will hydrate more cement
The
stickyness of the product will increase a lot
How
does UHPC differ from cement/concrete?
It
is the same, no difference
UHPC
is stronger in terms of compressive strength
UHPC
is more dense
Concrete
is more flexible
UHPC
can be installed under water
How
does UHPC differ from refractory?
It
i the same, no difference
Refractory
needs heat to finalize its reactions, UHPC does not
UHPC
is more wear resistant
The
insulation properties of UHPC is better than that of refractory
UHPC
can withstand higher temperatures compared to refractories
WPE DK International
Phone: 0049 176 601 73146
E-mail: ber@wpe-dk.dk
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