Preparing the substrate
Remove all degraded and/or loose concrete until a
sound and solid substrate is achieved.
Where necessary clean the concrete and reinforcing
steel by sweep blasting or other approved
mechanical methods, to remove all dirt, any
corrosion products, cement laitance, grease, oil, any
previous coatings and other deleterious elements.
Any previous repairs that are no longer thoroughly
bonded must also be removed.
Pre-soak the substrate with clean, potable grade
water to obtain a saturated surface dry (SSD)
condition.
Preparing the mortar
Pour into the mixer or a rust-free mixing vessel, the
pre-gauged amount of potable grade water needed
to obtain the required consistency.
Application Litres of water
per 25 kg bag
Trowel 2.75 – 3.25
Spray 3.25 – 3.75
Start the mixer and slowly add the complete bag of
SpECbuild MC500 Fibre to the water, in a
continuous flow;
Mix for 1 to 2 minutes; check to make sure the mix
is well blended. Scrape any unmixed powder from
the bottom and the sides of the mixer. Mix again for
a further 2 to 3 minutes;
Depending on the amount of mixed material
required, a mortar mixer or a slow speed heavy duty
drill with an appropriate mixing paddle may also be
used. Mix at low speed (300 rpm) to avoid entraining
air;
Avoid mixing manually as this may adversely affect
several of the mortars characteristics, including
mechanical strength, shrinkage, impermeability, etc;
SpECbuild MC500 Fibre can be applied at a
minimum thicknesses of 20 mm up to 60 mm in a
single layer. Additional buildup can be achieved
subject upon the repair area geometry, location and
roughness of the concrete substrate.
Reinforcement Steel Preparation
For repairing concrete elements damaged due to
reinforcement corrosion, it is recommended to use
mechanical means of abrasion in order to remove
the corrosion deposits from the exposed
reinforcement prior to coating with SpECcoat Zn25.
APPLICATION
Hand Application
SpECbuild MC500 Fibre may be applied by trowel
to vertical surfaces in layers up to 60 mm thick, or
for overhead applications in layers up to 30 mm
thick, without the use of formwork. Where higher
buildup of SpECbuild MC500 Fibre is required,
leave the surface of the previous layer in a rough
condition, allow to harden, then wet the surface with
water, prior to applying the second layer.
Spray Application
SpECbuild MC500 Fibre can be spray applied
using a suitable piston or worm-screw type rendering
machine, such as a Turbosol or Putzmeister. Do not
use a continuous mixing type rendering machine.
Precautions to be observed during application
In hot working conditions the following precautions
should be taken:
· Avoid direct exposure to sunlight for stored
material and also mixing equipment;
· Prior to use, the product must be stored
in a shaded area out of direct sunlight;
· Use cool water for mixing;
· Avoid application during the hottest time of the
day and/or in direct sunlight;
· Mix only sufficient material that can be applied
using available labour and equipment;
At low temperatures, prepare the mix with water
heated to approx. +20°C.
Curing
In accordance with good concrete practice, all
exposed surfaces of SpECbuild MC500 Fibre
must be immediately cured after application, using
wet hessian covered with polythene sheeting;
failure to cure the open surfaces can cause the
formation of cracks due to plastic shrinkage,
especially in hot and/or windy climatic conditions;
SpECcure WE should also be considered.
Spray water onto the surface of the application
within the first 8-12 hours and repeat the
operation for at least the first 48 hours. As an
alternative, after finishing the application of the
material, apply a coat of curing membrane such as
SpECcure WE or SpECcure AC. Film forming
curing membranes can impair the adhesion of
subsequent finishes
