INSTITUTE OF ARCHITECTURE AND CONSTRUCTION OF KAUNAS UNIVERSITY OF TECHNOLOGY THE ACCREDITED LABORAT

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INSTITUTE OF ARCHITECTURE AND CONSTRUCTIONOF
KAUNAS UNIVERSITY OF TECHNOLOGYTHE ACCREDITED
LABORATORY OF COMPOSITE AND FINISH TECHNOLOGY
BUILDING CONSTRUCTION ELASTIC REPAIR ADMIXTURES
EDITA SMETONAITE
Eindhoven 13-14 December 2006
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INTRODUCTION
The repair of the damaged and cracked building
constructions requires flexible and water
resistant mortars that are well adhesive to the
base. Some polymer cement mortars demonstrate
such properties. For a number of years, the
Institute of Architecture and Construction at KTU
has conducted investigations of the properties of
various polymer cement mortars and produced new
sorts polymer cement finish and building
materials for the protection and repair of the
building constructions. The compositions formed
on the basis of the acrylatic binder have been
investigated as the materials used for the repair
of the building constructions. Valuable
properties of such compositions are the
elasticity of the hardened products and good
adhesion to the base. Which were discussed in the
earlier articles. It should be stressed that such
products are also distinguished by they
sufficient durability. They well resist the
damaging water effect and cyclical freezing.
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CONCLUSIONS

• The investigation of the properties of
  acrylic repair products when the building is
  filled with different mineral fills and offer new
  sorts of repair materials that are distinguished
  by their elasticity, good adhesion to the base
  and suitable for the repair of the cracked
  constructions and render.

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MATERIALS

• The acrylatic binding was prepared which was
  well mixing with cement and the mineral fills of
  various coarseness. Since it was water binding,
  cement in the admixture might hydrate and harden.
  Fine, yet not unground sand and Portland cements
  were used for experiments.

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EXPERIMENTAL METHODS

• With the help of the laboratory equipment the
  extension by stretching of the mortar layer and
  strength of adhesion with concrete and strength
  against stretching have been determined. Strength
  against pressure and bending of the samples
  4x4x16 cm have also been determined. However,
  such properties may be determined exclusively for
  the mortars having a high degree of saturation
  with fills. The samples were tested after 21 days
  of hardening under ambient conditions. Then some
  of them were soaked in water for 17 days in order
  to determine their water absorption and the
  coefficient of softening. Other samples were
  soaked for a full year and the rest were
  periodically freezed in the freezing chamber and
  soaked in the 5 NaCl solution a single freezing
  soaking cycle was performed each day. During
  the process of hardening the spontaneous
  deformations were determined with the help of the
  clock indicators.

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RESULTS

• The mechanical properties of the acrilatic
  binder, of admixtures with the mineral fills and
  portlandcement have been determined.

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Fig. 1 Mechanical properties of the acrilatic
binder and fill mortars (sand cement) (11)
expansion by stretching strength against
stretching Rt, MPa and strength of adhesion to
concrete Rb, MPa
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• Fig. 1 displays the test results of the mortar
  layer expansion by stretching, strength against
  stretching and strength of adhesion with
  concrete. It is obvious that the product
  demonstrates high elasticity. Expansion by
  stretching may exceed 200. On the other hand, it
  shows that with the replacement of the entire
  mineral fill (i. e. fine, yet unground sand), by
  portlandcement, the data changes rather
  inconsiderably, which means that strength against
  stretching and strength of adhesion with concrete
  increased. With the use of the carbonate fills
  instead of sand, the positive results were
  obtained also.

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• With the increase of the fill amount in the
  composition of the mortar, the samples expansion
  by stretching decreases. The shaped samples, i.
  e. cubes and prisms get hardened which allows for
  the determination of their strength by against
  bending and against pressure. It should be noted
  that the to some extent elasticity of the mortars
  remains and the samples during their stretching
  or bending do not decay immediately.

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Table 1. The impact of the ratio between the
acrilatic binder and the fills on the properties
of the mortars
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• Table 1 displays the physical and mechanical
  properties of the mortars with the increased
  amount of fills. Such mortars distinguish by
  their considerable strength against pressure and
  against bending. They are also water resistant
  after 7 days of soaking in water the mechanical
  strength of the samples decreased inconsiderably.
  The values of the coefficient softening decrease
  with the increase of the amount of the fills. The
  mentioned indices get improved with the increase
  of the portlandcement amount in the mortars.
  Moreover, it has been determined that the mortars
  which were soaked in water for a full year
  demonstrated their subsequent hardening caused by
  the growth of their mechanical strength
  therefore they endure the cyclical freezing and
  heating. If after 7 days of soaking the
  mechanical strength decreases to 30 , so in a
  full year the strength increases to a similar or
  even higher degree. It is interesting to point
  out that after 300 freezing heating cycles, the
  strength does not decrease but rather increases
  and exceeds the strength of the soaked samples.
  It demonstrates the proper durability of the
  mortar.

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• Another good property of such mortars is their
  non-shrinking during hardening. After 28 days of
  hardening under the ambient conditions, the
  deformation of the samples made only 0.14 mm/m
  practically, they did not get deformed
• On the basis of the obtained results different
  mortar compositions of various purpose were
  formed and utilized in practice during the repair
  of the cracked concrete constructions, brick
  masonry and thin render. During the repair of the
  massive concrete or brick constructions, the
  existing cracks were enlarged, deepened (if
  necessary) and filled with the polymer cement
  mortar of adequate consistence. After hardening
  the repaired areas were finished by the
  unification of the colours of the repaired and
  surrounding areas.
• The finish of the facades with the exterior
  insulating systems and of render as well as their
  repair open an entirely new and unexplored
  problem here the defects appear due to various
  temperature and moisture deformations and other
  reasons. For the repair of such surfaces the
  materials of ananalogical composition yet more
  liquid and resembling the putty substance were
  used. Their hardened layers are elastic, they
  well endure the mechanical effects, including
  vibration

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CONCLUSIONS

• On the basis of acrilate polymers, elastic and
  long durable materials for the repair of the
  cracked constructions and facades were composed.
  Cement included into their composition increased
  water and frost resistance of the mortars
• The composed repair materials were successfully
  used in practice.