CEMENT & WOOD BUILDING PANELS
Characteristics of force according to international standards
3.2.1 General characteristics of force by
In order to limit pressure, should be taken specific measures MSZ
15025/1989 as a reference guide for the design and construction of
facilities under the supervision of the 'Institut Fur Bautechnik, Berlin
Correlation of bending strength with modules of elasticity in bending
Application of bending strength for loading perpendicular to Table
Application of tensile force in Table Top: 0,8 N/mm(q)
Application of compressive force in Table Top:
Elasticity modules in flexion for objective estimates:
There is a loosely linear correlation between bending strength and
modulus of elasticity in
bending building plates. All
of this is shown in Figure 17.
Deformation force of
Specimens of uniform cross sections, but with different lengths used in
Figure 18 shows
the different relationships of smallness and the corresponding core
value of strength.
Essential value as a function of scarcity
In the case of the
table, the deformation is normally done on large plates instead of rods. The
force of deformation of the table can be fixed through a simple
calculation with sufficient accuracy.
Conduct of concrete attached to the particle board under the influence
of thermal load
As for the excellence of suitable instruments for the characterization
of structural materials, the thermodynamics curve is obtained by tracing
the deformation as a function of time.
Figure 19. shows
the deformation in the specific individual values of temperature and two
levels of tension.
Thermodynamic curve of
curve corresponding to 35% of the bending strength;
i.e. nominal tension §1 = 3,79 MPa
2. curve corresponding to 70%
of the bending strength;
i.e. nominal tension §2 = 7,59 MPa
Thermodynamic curve can be considered linear up to 120 ° C
The straight sections corresponding to the maximum nominal function
is steep, due to the significant effect of temperature in the
non-linear plot of curvature;
For functions and starting from a higher nominal temperature of 100
° C, an increasing number of sample tests have not passed the load
test while at a temperature of 140 ° C all samples were negative
because they have not passed the test.
Starting at a temperature of 120 ° C - for both
levels of tension - there is a sudden increase of strain specific. This
is therefore indicated that the maximum thermal load of the
is 120 C °.
Effect of moisture content on the values of strength
The many values of strength of concrete combined with shavings are
correlated with the moisture content prevailing at a function of time. Figure
shows this relationship.
changes in strength as a function of moisture content.
It can be argued that the force of compression and bending strength
decreased considerably, due to an increase in moisture content.
Bending, transverse force and the breaking force and impact change
slightly under the influence of moisture content. The
breaking force and impact, in contrast to other priorities of strength,
rising slightly due to an increase in moisture content. Obviously,
this follows from the fact that the holes are filled with water to
increase the level.
Hardening of the boards construction BETONYP due to the strength of
For load-bearing structures designed for longer life,
the change of individual properties in time plays a significant role. As
a result of the macromolecular composition of wood, certain mechanical
properties undergo changes even if load and physical properties remain
unchanged which should be considered, when designing building
structures. The science of rehology deals with the stresses and
deformations caused by loading as a function of time.
Yo = iniziale curvatura elastica all’uniforme 1/H
Y = curvatura al tempo T
T = tempo
§ = coefficiente di carico
Cambiamento nella piegatura delle tavole edili BETONYP in funzione di
coefficiente, di carico e di tempo.
has proved that the initial elastic deformations are much more
favourable for the cement-bonded chipboards than for the traditional
chipboards. It is mainly due to the higher flexural rigidity. The
initial elastic deflection for the BETONWOOD building boards is only
about 1/5 of the values obtained for furniture-grade chipboards.
degree of creep can be characterized clearly by the multiplication
factor a, which depens on the load time and when multiplied by Yo
yields the actual deformation corresponding to load time t. Although the
values a for cement-bonded chipboards are usually 2-4 times
higher than those obtained for standard chipboards, if the load time
exceeds 1 year, the actual deformations will be significantly lower.
creep of cement-bonded chipboards consists of three main phases:
I: In this initial phase the deformation occurs at the highest rate and
lasts for 3-5 days /100 hours at average/.
II: The rate of deformation becomes constant, the deformations show
linear increase as a function of time and last for 5-30 days.
III: The creep will practically stop or slow down to a degree that is
3.215 Condizioni di equilibrio per il carico delle tavole edili
q = carico distribuito in maniera uniforme (kn/m(q))
l = larghezza (cm)
f = curvatura (mm)
rapporto tra lo spessore della tavola, larghezza, carico di
distribuzione e curvatura.
Figura 22. mostra il rapporto tra il carico, la larghezza, lo spessore
della tavola e la curvatura delle tavole edili BETONYP posizionate su
schema di carico per tre fasce di sostegno.
Q = carico distribuito in maniera uniforme (kn/m(q))
L = larghezza (cm)
Spessore in mm
carico distribuito in maniera uniforme
La larghezza richiesta per la tavola posizionata su tre sostegni in
funzione di spessore della tavola e carico distribuito. Lo schema di
carico è mostrato nella figura 23.
3.22 Fissaggio di chiodi sul cemento unito al truciolare
Nella figura 24 viene mostrato il disegno schematico di test di chiodi.
Disegno schematico di fissaggio di chiodi e viti.
Chiodi usati nei test: 30 x 3 mm. Livello di pre – foratura: 0,8 Dsz.
metodo di test
A (perpendicolare al livello della tavola)
B (parallelo al livello della tavola)
valori di fissaggio di chiodi su tavole edili BETONYP
Screwholding of the
Screwholding is considerably effected by the design of screw used for
Degree of preboring: 0,8 dcs
Results of test conducted usign screw of 40 X 4 mm size in conformity
with the requirements of DIN 96.
3.24 Fungus and insect resistance of the BETONWOOD building boards
test of cement-bonded chipboards for their fungus resistance were
conducted in 1976 by the Department of Forest Protection Methods in the
University for Forestry and Wood Industry.
tests of baords for their mould resistance have been carried out in
conformity with the specifications of Standard MSZ 8888/9-69. The tests
have proved that the BETONWOOD building boards are “fungicides”.
tests for resistance against wood rotting fungi has been conducted in
conformity with the specifications of Standard MEMSZ 50 373. The
cultures of Coniophora cerebella, Poria vaporaria and Trametes
versicolor, that is, fungi most damaging to building structures, have
been used in the trials: None of the fungus species damaged the
BETONWOOD building boards, thus, it has been proved that the
cement-bonded chipboard is “fungus resistant”. This finding has been
confirmed by the test report made by Mutsui Lumber Company, Tokyo.
has been proved by tests carried out at various European institutes that
the termites do not attack the BETONWOOD building board even in the
starvation phase. \BAM, Bundesanstalt fur Materialprufung, Berlin, test
report No. 5.1, \4403,1985\.
insect resistance of BETONWOOD building boards has been confirmed also
by the test conducted at the University of Tokyo, Faculty of
3.25 Weather resistance of the BETONWOOD building boards
cement-bonded chipboards are weather resistant, since the wood chip
particles are protected by the set cement against external damaging
material of formworks completely or partially dug in the earth did not
show damage during test carried out for many years. The headquarters of
the BETONWOOD S.r.l. was built with socle partly made of lost
cement-bonded chipboard shuttering. The nearly twenty-year-old
structures have not undergone any changes. The test series conducted in
this subject by the Woodworking Research Institute also confirmed these
results. The cement-bonded chipbaord has been tested by EMPA/Switzerland,
1975/ in a series of measurements consisting of 150 cycles at
temperature of -20oC and +20oC and at varying moisture content. These
tests qualified the board as definitely frost-resistant.
follows that the BETONWOOD building board without finishing will
withstand weathering and extreme stresses.
Permanent stress-change in relative humidity, effects of direct rain,
water and steam-cause a change in the moisture content of the board.
/see 3.105 and 3.106
change in the moisture content of the cement-bonded chipaboard causes
dimensional change /see 3.107/.
Dimensional change in plane:
temperature of +20°C, when the relative humidity changes from 25% to
90%: max. 0,3%.
+-10% change in moisture content of the board: +-2mm/m
designing structures, these dimensional changes should be taken into
practice more favourable values will be obtained.
Quality Control Institute for the Building Industry obtained the
following results by testing cement-bonded chipboard in a FEUTRON device
for 96 hours in an atmosphere maintened at 60°C temperature and at 100%
Dimensional change in plane 0,15
report of EMI Nr. M-34/1975)
Risultati dei test effettuati con viti 40x4 mm in conformità con i
requisiti DIN 96.