BETONYP meccaniche

MECHANICALS PROPERTIES OF Betonyp ® CEMENT & WOOD BUILDING PANELS

List 8. Characteristics of force according to international standards

3.2.1 General characteristics of force by Betonyp ® building panels

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 ".

Figure 17. Correlation of bending strength with modules of elasticity in bending for Betonyp ® building panels

Application of bending strength for loading perpendicular to Table Top: 1,8 N/mm(q)
Application of tensile force in Table Top: 0,8 N/mm(q)
Application of compressive force in Table Top: 2,5 N/mm(q)
Elasticity modules in flexion for objective estimates: 2000 N/mm(q)

There is a loosely linear correlation between bending strength and modulus of elasticity in Betonyp ® bending building plates. All of this is shown in Figure 17.

3.2.11 Deformation force of Betonyp ® building boards

Specimens of uniform cross sections, but with different lengths used in testing. Figure 18 shows the different relationships of smallness and the corresponding core value of strength.

Figure 18. Essential value as a function of scarcity of Betonyp ® building boards

In the case of the Betonyp ® 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.

3.212 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.

Figure 19. Thermodynamic curve of Betonyp ® table.

1. 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

Tests indicated that:

Thermodynamic curve can be considered linear up to 120 ° C temperature;
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 Betonyp ® building tables is 120 C °.

3.213 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 20. clearly shows this relationship.

Figure 20. 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.

3.214 Hardening of the boards construction BETONYP due to the strength of flexion

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

Figura 21. Cambiamento nella piegatura delle tavole edili BETONYP in funzione di coefficiente, di carico e di tempo.

The test 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.

The 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.

The creep of cement-bonded chipboards consists of three main phases:

Phase I: In this initial phase the deformation occurs at the highest rate and lasts for 3-5 days /100 hours at average/.

Phase II: The rate of deformation becomes constant, the deformations show linear increase as a function of time and last for 5-30 days.

Phase III: The creep will practically stop or slow down to a degree that is negligible.

3.215 Condizioni di equilibrio per il carico delle tavole edili BETONYP

q = carico distribuito in maniera uniforme (kn/m(q))

l = larghezza (cm)

f = curvatura (mm)

Figura 22. 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 due sostegni

Figura 23. 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

larghezza (cm).

Tabella 9. 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.

Figura 24. Disegno schematico di fissaggio di chiodi e viti.

Chiodi usati nei test: 30 x 3 mm. Livello di pre – foratura: 0,8 Dsz.

Sp. (mm)

metodo di test

A (perpendicolare al livello della tavola)

B (parallelo al livello della tavola)

Tabella 10. valori di fissaggio di chiodi su tavole edili BETONYP

3.23 Screwholding of the cement-bonded chipboards

Screwholding is considerably effected by the design of screw used for test.

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

The 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.

The 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”.

The 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.

It 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\.

The insect resistance of BETONWOOD building boards has been confirmed also by the test conducted at the University of Tokyo, Faculty of Agriculture.

3.25 Weather resistance of the BETONWOOD building boards

The cement-bonded chipboards are weather resistant, since the wood chip particles are protected by the set cement against external damaging effects.

The 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.

It 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

A change in the moisture content of the cement-bonded chipaboard causes dimensional change /see 3.107/.

Dimensional change in plane:

At a temperature of +20°C, when the relative humidity changes from 25% to 90%: max. 0,3%.

In practice:

For +-10% change in moisture content of the board: +-2mm/m

When designing structures, these dimensional changes should be taken into account.

In practice more favourable values will be obtained.

The 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% relative humidity.

Thickness swelling 0,92%

Dimensional change in plane 0,15

(Test report of EMI Nr. M-34/1975)