## 3 Process of Designing WMA with Zeolites  
Based on many years of WMA studies, it is possible to state that the process of designing a WMA mix recipe has a similar course to the design of a hot mix asphalt recipe [22; 23]. The stages of designing the composition of WMA mix with zeolite addition are shown in Table 2. Steps in the design of WMA was adopted on the basis of the recommendations National Cooperative Highway [22].  
Individual settings for mix asphalt production and compaction temperatures give rise to significant differences. Determination of additive amount is an important aspect in case of using zeolites. According to the literature data, the amount of zeolite addition may range between 0.25% and 1.0% of the mix asphalt mass:  
* For Linde A zeolite: 0.25%-0.3%
* For Na-P1 zeolite: 0.5%
* For clinoptilolite: 1.0%
* For zeolites modified with water (clinoptilolite and Na-P1): 0.4%.  
The optimal amount of dosed zeolite material can be determined using a compactibility test in a gyratory compactor [20].  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
\begin{tabular}{c} \\ \\ \end{tabular} \\  & & \\ \hline \hline \end{tabular}
\end{table}
Table 1: Characterization of used zeolite structures.  
In the process of designing WMA, it is important to determine the mix asphalt production and compaction temperature. A method of determining appropriate compaction temperature involves a comparison of the volumetric density or air void content in compacted WMA samples and reference HMA (Figure 1). This method can be used for all WMA technologies.  
The temperature at which the compared values (volumetric density/air void content) in HMA and WMA samples are the same is the correct sample compaction temperature in the laboratory.  
In order to determine technology temperatures and optimal dosage of zeolite addition in the compactability test several concentrations of zeolite material and several production temperatures should be included. In the next stage, a compactability test should be performed for each of the combinations (zeolite concentration-production temperature). This procedure is time consuming, but another method is unknown at the moment.  
\begin{table}
\begin{tabular}{c p{142.3 pt} p{142.3 pt}} \hline \hline
**No.** & **Stages of Recipe Design** & **Differences Compared to Designing Traditional Mix** \\  & & **Asphal Composition** \\ \hline  & & Selection of zeolite type. \\
1. & Primary data. & Determining the amount of used zeolite, e.g., using gyratory compaction test \\  & & Determining the need to use other additives, e.g., agents improving aggregate adhesion to asphalt. \\ \hline
2. & Selection of aggregate type and design of mineral mix. & 1. Recipe design without changes; 2. Decreasing the amount of dosed limestone fillers by the amount of added zeolite. \\ \hline
3. & Determining the amount of dosed asphalt. \\ \hline
4. & Determining technology temperatures. & Individual setting depending on the aim of using WMA mix, based on mix asphalt compatibility studies. \\ \hline
5. & Determining the conditions of preparing and compacting samples. & Compaction energy without changes. Necessity to follow batch conditioning. Time—minimum of 45 min. \\ \hline
6. & Scope of Laboratory Tests. & No changes. \\ \hline
7. & Assessment criteria for designed mineral-asphalt mix. & No changes. \\ \hline \hline \end{tabular}
\end{table}
Table 2: Stages of designing WMA (warm mix asphalt) mix composition with zeolite addition and differences in terms of HMA (hot mix asphalt).  
Figure 1: Method of determining WMA (warm mix asphalt) sample compaction temperature through the comparison of air void content.