Table 3: The results of pull-off and shear strength tests for the C2S1 adhesive from the sample together with the relative δ data and the absolute precision estimation Δ .

Where:

δ – relative precision of estimation

mo – assumed expected value

m – expected value

X – the arithmetic mean of the random sample

Δ – absolute precision of estimation

t𝛼,s – reading from Student’s t-charts (for α=0,1)

Sx – standard deviation from the sample

n – random sample size

a. pull-off (dry) with EPS: 0.1955 < m < 0.2260 MPa

b. pull-off (wet) with EPS: 01850 < m < 0.2198 MPa

c. shear with EPS: 0.5174 < m < 0.6160 MPa

d. pull-off (dry) with XPS: 0.2530 < m < 0.2888 MPa

e. pull-off (wet) with XPS: 0.2028 < m < 0.2420 MPa

f. shear with XPS: 0.9900 < m < 1.1475 MPa

The designated intervals are one of those that can be treated with 90% certainty to cover the expected strength value for C2S1 in individual research models. Comparing the obtained results, it can be claimed that C2S1 characterizes by the greater shear and tensile strength is characterized C2S1 with the XPS insulation than the EPS insulation in dry conditions. It confirms the assumption contained in the article [4].

Verification of hypotheses regarding minimum C2S1 adhesive strength according to [7], using the pull-off method in dry conditions with EPS insulation.

Based on the obtained results, we can hypothesize that the expected value of the C2S1 strength adhesive with EPS isolation using the pull-off method (dry conditions) is higher than 0, 1955 MPa.

H0: m = 0.1955 H1: m > 0.1955

Using the t-test to verify the null hypothesis we get:

Comparing the obtained result with the critical value t2𝛼,s = t0.2; 12 = 1.356 read from the Student’s t-charts [6] at the righthanded alternative hypothesis, we can conclude that the test result is higher than the critical value (located in the critical area), which authorizes the rejection of the null hypothesis in favor of the alternative hypothesis. This means that for 90% certainty, the expected strength value of the C2S1 adhesive in EPS isolation using the pull-off method (dry conditions) is higher than 0.1955 MPa. In order to estimate the minimum strength of the C2S1 adhesive with EPS isolation using the pull-off method (dry conditions), with the results obtained from the carried-out samples, for α = 0.10 we can make calculations using the formula for the t-test:

Hence

The obtained result can be treated with 90% certainty as the minimum strength of the C2S1 adhesive with EPS insulation for pull-off method with dry conditions.

Using the above procedure, the data from Table 3 and the formulas were determined the minimum strength of the C2S1 adhesive in other performed tests. They are:

a) in the pull-off method (wet conditions) with EPS insulation

The obtained result can be treated with 90% certainty as the minimum strength of the C2S1 adhesive with EPS insulation for shear strength. Critical value krytyczna t2𝛼,s = t0.2 ; 8 = 1.397 read from the Student’s t-charts at the right-handed alternative hypothesis.

c) in pull-off method (dry conditions) with XPS insulation

The obtained result can be treated with 90% certainty as the minimum strength of the C2S1 adhesive with XPS insulation for pull-off method (dry conditions). Critical value t2𝛼,s = t0.2 ; 14 = 1.345 read from the Student’s t-charts at the right-handed alternative hypothesis.

d) in pull off method (wet conditions) with XPS insulation

The obtained result can be treated with 90% certainty as the minimum strength of the C2S1 adhesive with XPS insulation for pull-off method (wet conditions). Critical value t2𝛼,s = t0.2 ; 9 = 1.383 read from the Student’s t-charts at the right-handed alternative hypothesis.

e) in shear strength with XPS insulation

The obtained result can be treated with 90% certainty as the minimum strength of the C2S1 adhesive with XPS insulation for shear strength. Critical value krytyczna t2𝛼,s = t0,2 ; 7 = 1,415 read from the Student’s t-charts at the right-handed alternative hypothesis.

Conclusion

The statistical analysis of the C2S1 type adhesive strength for pull-off method in dry and wet conditions and shear strength in dry conditions, which combines the tiles of two types of EPS 200 or XPS 300 insulation substrate, showed that:

a) A higher minimum shear and tensile strength was demonstrated using an XPS insulating substrate relative to EPS

b) Minimum strengths of the C2S1 adhesive, which can be treated with 90% certainty

1. depending on the insulating base:

a. 0.20MPa with EPS insulation for pull-off method in dry condition

b. 0.19MPa with EPS insulation for pull-off method in wet condition

c. 0.26MPa with XPS insulation for pull-off method in dry condition

d. 0.21MPa with XPS insulation for pull-off method in wet condition

e. 0.53MPa with EPS insulation for shear strength

f. 1.00MPa with XPS insulation for shear strength

Acknowledgement

The author of the article would like to thank Mrs. Elzbieta Golabeska from the Bialystok University of Technology for providing statistical literature. The research was carried out as part of my own work from Bialystok University of Technology No. W/WBIIŚ/15/2019, financed from the subsidy provided by the Ministry of Science and Higher Education.

References

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