## 3 Results
### Analysis of Significance of Effects
The results have been categorised according to the type of characteristic under investigation and are depicted in Figure 10.  
As presented in Figure 10, a marginal difference can be discerned between the compressive strength results after 28 days and 56 days of mortar curing. Furthermore, a discernible declining trend in compressive strength was noticed irrespective of the curing duration. By scrutinising the error bars, it is not feasible to definitively deduce for which quantities of PET and glass the alteration in the value of the dependent characteristics is or is not significant. This is consequential considering the potential recycling of PET polymer and glass waste. The search for contrasts was performed using the Tukey test, elaborated in the 1950s. It resulted from some discrepancies in the procedure described by [PERSON] concerning a least significant difference procedure. A significant difference of the Tukey to [PERSON]'s test is the equal probability of committing a type I error, independent of the number of comparisons, which does not exceed the assumed level of significance in accordance with Formula (1):  
\[HSD=q_{\alpha,k,N-k}\sqrt{\frac{MSE}{n}} \tag{1}\]  
where \(HSD\) is the honestly significant difference, \(q_{\alpha,k,N-k}\) is the tabulated quantile of the standardised range distribution, \(MSE\) is the mean square error, \(N\) is the total samples number, and \(n\) is the sample number in the group. As a result, any difference between two groups greater than the HSD is considered a significant pair. The list of relevant groups is determined iteratively by searching through all combinations. Therefore, the  
Figure 10: Interaction diagram of the weighted means of the studied characteristics. number of similarities varies depending on the nature of the research object under study (its repeatability). This Tukey test can be performed for any confidence interval, which was set at 0.05 in the research. The groundwork for distinguishing contrasts between the average scores allotted to each combination of PET and glass quantities is furnished by an analysis of variance. This indicates the existence, at the very least, of a significant pair between the average scores for the instances (Table 3). To achieve this, a conservative [PERSON]'s test (post hoc) was used [44]. For its application, preliminary [PERSON]'s tests of variance homogeneity were conducted. The outcome of the test manifested that there was no ground to assert that the variability of the results differed amongst the case groups. The findings are delineated in the subsequent Tables 6-9. Reviewing the data in Table 6, it is notable that the incorporation of up to 10% glass and up to 5% PET does not induce a substantial change (reduction) in the compressive strength of the mortar after 28 days, compared to the reference mortar. The most significant decline in compressive strength after 28 days was observed when glass was incorporated at 20%, irrespective of the quantity of PET added. The subsequent impact of the additives on the mortar strength over time is evident in the comparisons made for the compressive strength characteristic after 56 days (Table 7). It is worth noting that the group of results represented by the reference mortar is marked by number 1. It should be stated that when dosing separately, PET up to 10% and glass up to 10% do not result in a significant difference in compressive strength results after 56 days of curing compared to the reference mortar (without additives). This conclusion follows from the juxtaposition of the similarities of fuzzy sets 1 and 2. Observing the extent of variation in the mean strength (Table 7) after 56 days of curing and the number of similarities within the groups compared to the compressive strength after 28 days, it should be concluded that there is a deceleration in the dynamics of compressive strength increase over time. The simultaneous use of glass and PET, especially at 20% glass content, results in a significant reduction in strength after 56 days of maturation.