{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,1]],"date-time":"2026-09-01T12:09:31Z","timestamp":1788264571530,"version":"build-2803163510"},"reference-count":50,"publisher":"MDPI AG","issue":"21","license":[{"start":{"date-parts":[[2025,10,23]],"date-time":"2025-10-23T00:00:00Z","timestamp":1761177600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Natural Science Foundation of Guizhou Minzu University","award":["No. GZMUZK [2021]QN03"],"award-info":[{"award-number":["No. GZMUZK [2021]QN03"]}]},{"name":"Guizhou Provincial Basic Research Program","award":["No. QKHJC- ZK[2021]YB 288"],"award-info":[{"award-number":["No. QKHJC- ZK[2021]YB 288"]}]},{"name":"Guizhou Provincial Basic Research Program","award":["No. Qian Ke He Basic - [2025] Youth 306"],"award-info":[{"award-number":["No. Qian Ke He Basic - [2025] Youth 306"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Polymers"],"abstract":"<jats:p>This study aimed to systematically evaluate the rheological properties of warm mix flame-retardant asphalt (WMFRA). First, conventional performance tests were conducted on the prepared warm mix rubberized asphalt (WMRA), incorporating different warm mix agents in order to screen out an agent with optimum performance. Subsequently, limestone power (LP), aluminum trihydrate (ATH), OA composed of ATH and organically modified montmorillonite (OMMT), and zinc borate (ZK) were employed in the oxygen index (OI) test of WMFRA to determine the optimal dosage of flame retardants. Finally, a dynamic shear rheometer (DSR) and a bending beam rheometer (BBR) were used to evaluate the rheological properties of WMFRA. The results showed that the R-Type warm mix agent was superior to S-Type in reducing consistency and improving low-temperature cracking resistance but slightly weakened high-temperature stability. The OA composite flame retardant could enhance the OI from 20.16% to 24% at 15wt% dosage, thereby meeting the specified flame-retardant requirement. Furthermore, OA could markedly boost the high-temperature performance of WMFRA, exhibiting significantly higher complex modulus (G*) and rutting factor (G*\/sin\u03b4) compared to WMFRA with other flame retardants. In general, all flame retardants reduced the temperature sensitivity of WMFRA, with ZK being the most effective at 12.6%. Regarding low-temperature performance, LP and ATH improved stress relaxation of WMFRA, while ZK and OA impaired this capability. All flame retardants reduced low-temperature flexibility, but the low-temperature behavior was still dominated by the S(t). For fatigue performance, LP and ATH degraded the fatigue performance by advancing the damage time by 958.9 s and 669.7 s, respectively. In contrast, ZK improved fatigue performance by increasing the complex shear modulus, thereby extending the fatigue life (Nf50) by 3.2%. This study provided a theoretical basis for the formulation optimization of WMFRA.<\/jats:p>","DOI":"10.3390\/polym17212829","type":"journal-article","created":{"date-parts":[[2025,10,24]],"date-time":"2025-10-24T01:35:11Z","timestamp":1761269711000},"page":"2829","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":3,"title":["Evaluation of Rheological Properties of Warm Mix Flame-Retardant Asphalt (WMFRA) Binder Suitable for Tunnel Area"],"prefix":"10.3390","volume":"17","author":[{"given":"Bo","family":"Zhang","sequence":"first","affiliation":[{"name":"School of Civil Engineering and Architecture, Guizhou Minzu University, Guiyang 550025, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juan","family":"Liu","sequence":"additional","affiliation":[{"name":"School of Civil Engineering and Architecture, Guizhou Minzu University, Guiyang 550025, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Qiaoli","family":"Le","sequence":"additional","affiliation":[{"name":"School of Civil Engineering and Architecture, Guizhou Minzu University, Guiyang 550025, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhen","family":"Lu","sequence":"additional","affiliation":[{"name":"School of Civil Engineering and Architecture, Guizhou Minzu University, Guiyang 550025, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,10,23]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"118584","DOI":"10.1016\/j.watres.2022.118584","article-title":"Characterization of contaminant leaching from asphalt pavements: A critical review of measurement methods, reclaimed asphalt pavement, porous asphalt, and waste-modified asphalt mixtures","volume":"219","author":"Azadgoleh","year":"2022","journal-title":"Water Res."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2737","DOI":"10.1007\/s10694-024-01556-2","article-title":"Fire-retarding asphalt pavement for urban road tunnels: A state-of-the-art review and beyond","volume":"61","author":"Jiang","year":"2024","journal-title":"Fire Technol."},{"key":"ref_3","doi-asserted-by":"crossref","unstructured":"Leng, C., Lu, G.Y., Gao, J.L., Liu, P.F., Xie, X.G., and Wang, D.W. (2019). Sustainable green pavement using bio-based polyurethane binder in tunnel. Materials, 12.","DOI":"10.3390\/ma12121990"},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"124","DOI":"10.1016\/j.undsp.2024.05.005","article-title":"Experimental study on effect of pavement background on obstacle visibility in LED lighting environment of road tunnel","volume":"22","author":"Feng","year":"2025","journal-title":"Undergr. Space"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"143653","DOI":"10.1016\/j.cej.2023.143653","article-title":"Metal\u2013organic frameworks\u2013based flame-retardant system for epoxy resin: A review and prospect","volume":"468","author":"Song","year":"2023","journal-title":"Chem. Eng. J."},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Patel, R., Chaudhary, M.L., Patel, Y.N., Chaudhari, K., and Gupta, R.K. (2025). Fire-Resistant Coatings: Advances in Flame-Retardant Technologies, Sustainable Approaches, and Industrial Implementation. Polymers, 17.","DOI":"10.3390\/polym17131814"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"841","DOI":"10.1016\/j.conbuildmat.2019.03.118","article-title":"Flame retardant and its influence on the performance of asphalt\u2014A review","volume":"212","author":"Xiao","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"468","DOI":"10.1016\/j.conbuildmat.2018.11.034","article-title":"Review of the flame retardancy on highway tunnel asphalt pavement","volume":"195","author":"Qiu","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"130996","DOI":"10.1016\/j.conbuildmat.2023.130996","article-title":"Preparation and properties of flame-retardant asphalt containing polyurethane and eco-friendly flame retardants","volume":"375","author":"Liu","year":"2023","journal-title":"Constr. Build. Mater."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"189","DOI":"10.4028\/www.scientific.net\/AMR.531.189","article-title":"Preparation of flame-retardant asphalt for tunnels","volume":"391\u2013392","author":"Tian","year":"2012","journal-title":"Adv. Mater. Res."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"139152","DOI":"10.1016\/j.conbuildmat.2024.139152","article-title":"Development and performance evaluation of composite flame retardant based on the thermodynamic properties of asphalt components","volume":"455","author":"Li","year":"2024","journal-title":"Constr. Build. Mater."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1007\/s11051-023-05697-3","article-title":"Effect of halloysite nanotubes (HNTs) and organic montmorillonite (OMMT) on the performance and mechanism of flame retardant-modified asphalt","volume":"25","author":"Tan","year":"2023","journal-title":"J. Nanoparticle Res."},{"key":"ref_13","doi-asserted-by":"crossref","unstructured":"Yang, M., and Yuan, B.H. (2025). Modification of Aluminum Hydroxide by Ball Milling: A Feasible Method to Obtain High-Efficiency Flame Retardants for Production of High-Performance EVA Composites. Materials, 18.","DOI":"10.3390\/ma18050984"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"1393","DOI":"10.1177\/0892705718798409","article-title":"Comparative study of toxicity for thermoplastic polyurethane and its flame-retardant composites","volume":"32","author":"Liu","year":"2019","journal-title":"J. Thermoplast. Compos. Mater."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"04024275","DOI":"10.1061\/JMCEE7.MTENG-18182","article-title":"Flame retardancy and rheological properties of warm-mix rubber asphalt binder containing various flame retardants","volume":"36","author":"Wang","year":"2024","journal-title":"J. Mater. Civ. Eng."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Pan, R. (2024). Fatigue Performance Evaluation of Warm-Mixed Rubber Asphalt Mixture for Stress Absorption Layer in Cold Area. Buildings, 14.","DOI":"10.3390\/buildings14123817"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"94","DOI":"10.7250\/bjrbe.2018-13.403","article-title":"Application of WMA technology to bituminous base course mixes","volume":"13","author":"Choudhary","year":"2018","journal-title":"Balt. J. Road Bridge Eng."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"141905","DOI":"10.1016\/j.conbuildmat.2025.141905","article-title":"Compaction optimization of surfactant-tailored basalt-fiber WMA by improved lubrication and micro-structure formation","volume":"484","author":"Gong","year":"2025","journal-title":"Constr. Build. Mater."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"38","DOI":"10.1016\/j.conbuildmat.2014.01.093","article-title":"Evaluation of mixture characteristics of warm mix asphalt involving natural and synthetic zeolite additives","volume":"57","author":"Topal","year":"2014","journal-title":"Constr. Build. Mater."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2269640","DOI":"10.1080\/23311916.2023.2269640","article-title":"Investigating the effect of nanomaterials on the Marshall properties and durability of warm mix asphalt","volume":"10","author":"Aljbouri","year":"2023","journal-title":"Cogent Eng."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"109094","DOI":"10.1016\/j.mtcomm.2024.109094","article-title":"Tuning high-and low-temperature rheological properties of warm-mixing asphalt composites by functionalized waxes","volume":"39","author":"Han","year":"2024","journal-title":"Mater. Today Commun."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"556","DOI":"10.1080\/10916466.2020.1772820","article-title":"Rheological properties and viscosity reduction mechanism of SBS warm-mix modified asphalt","volume":"38","author":"Gao","year":"2020","journal-title":"Pet. Sci. Technol."},{"key":"ref_23","doi-asserted-by":"crossref","unstructured":"Dong, F.Q., Yu, X., Liang, X.M., Liu, S.J., Ding, G.Y., and Xu, B. (2018, January 6\u20138). The Influence of Foaming Water Content on the Aging Characteristic of Foamed Warm-Mix Asphalt. Proceedings of the Transportation Research Congress 2016: Innovations in Transportation Research Infrastructure, Beijing, China.","DOI":"10.1061\/9780784481240.011"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"04025260","DOI":"10.1061\/JMCEE7.MTENG-20245","article-title":"Molecular-Scale Study of the Compatibility of Warm-Mix Agents, Rubber, and Asphalt in Warm-Mix Rubber Asphalt","volume":"37","author":"Huang","year":"2025","journal-title":"J. Mater. Civ. Eng."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"04022342","DOI":"10.1061\/(ASCE)MT.1943-5533.0004501","article-title":"Chemo-rheological characterization of aging behaviors of warm-mix high-viscosity modified asphalt","volume":"34","author":"Chen","year":"2022","journal-title":"J. Mater. Civ. Eng."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"950550","DOI":"10.3389\/fmats.2022.950550","article-title":"Effect of Sasobit warm mix on micro properties of asphalt with different degrees of regeneration","volume":"9","author":"Tong","year":"2022","journal-title":"Front. Mater."},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Zhang, J.Z., Li, P.Z., Sun, C.J., Liang, M., Li, Y.Y., Yao, Z.Y., and Zhang, X.M. (2019). Effects of composite warm mix additive (CAR) on the physical and rheological performance of bitumen and the pavement performance of its concrete. Materials, 12.","DOI":"10.3390\/ma12233916"},{"key":"ref_28","unstructured":"Wang, J.J., Li, H.Q., Chen, X.G., and Peng, C. (2025). Influence of different types of warm mix agents on the viscosity reduction effect of Karamay modified asphalt. China Highw., 96\u201399."},{"key":"ref_29","first-page":"624","article-title":"Research on the preparation and performance of warm-mixed high-viscosity modified asphalt in alpine region","volume":"54","author":"Qin","year":"2025","journal-title":"Appl. Chem. Eng."},{"key":"ref_30","first-page":"653","article-title":"Research progress on warm mixing technology of asphalt mixture","volume":"39","author":"Tang","year":"2020","journal-title":"China Mater. Prog."},{"key":"ref_31","first-page":"20102","article-title":"Research on construction workability of asphalt-rubber mixture with warm mix additives","volume":"46","author":"He","year":"2015","journal-title":"Funct. Mater."},{"key":"ref_32","unstructured":"He, S. (2021). Research on the Application of Warm Mixing Technology for Modified Asphalt Pavement in Expressway Tunnels. [Master\u2019s Thesis, Chang\u2019an University]."},{"key":"ref_33","unstructured":"Wu, B. (2015). Research on the Flame Retardant System and Road Performance of Composite Hydroxide Asphalt. [Master\u2019s Thesis, Zhejiang University]."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"04023058","DOI":"10.1061\/(ASCE)MT.1943-5533.0004726","article-title":"Mechanism of a warm-mix agent and its effects on the rheological properties and thermal stability of aluminum hydroxide and organic montmorillonite composite flame-retardant asphalt","volume":"35","author":"Wu","year":"2023","journal-title":"J. Mater. Civ. Eng."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"04024248","DOI":"10.1061\/JMCEE7.MTENG-17201","article-title":"Rheological Properties and Micromechanism of Warm-Mix Flame-Retardant Asphalt","volume":"36","author":"Liu","year":"2024","journal-title":"J. Mater. Civ. Eng."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"139578","DOI":"10.1016\/j.conbuildmat.2024.139578","article-title":"Microscopic morphology and adhesion performance of SBS\/OMMT modified asphalt under chloride salt erosion","volume":"458","author":"Xu","year":"2025","journal-title":"Constr. Build. Mater."},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Ghasemirad, A., Bala, N., and Hashemian, L. (2020). High-temperature performance evaluation of asphaltenes-modified asphalt binders. Molecules, 25.","DOI":"10.3390\/molecules25153326"},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Zhang, X.R., Han, C., Yang, J., Xu, X.Q., and Zhang, F. (2021). Evaluating the rheological properties of high-modulus asphalt binders modified with rubber polymer composite modifier. Materials, 14.","DOI":"10.3390\/ma14247727"},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"130758","DOI":"10.1016\/j.conbuildmat.2023.130758","article-title":"The rheological properties of high-viscosity modified reclaimed asphalt binder at multiple application temperatures","volume":"372","author":"Wang","year":"2023","journal-title":"Constr. Build. Mater."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1416246","DOI":"10.3389\/fmats.2024.1416246","article-title":"Rheological properties and 3D printability of SBS\/CR-modified asphalt binder with C9 petroleum resin for crack filling","volume":"11","author":"Niu","year":"2024","journal-title":"Front. Mater."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"116867","DOI":"10.1016\/j.conbuildmat.2019.116867","article-title":"The synergistic effect of organic montmorillonite and thermoplastic polyurethane on properties of asphalt binder","volume":"229","author":"Jia","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"679","DOI":"10.1016\/j.conbuildmat.2019.02.145","article-title":"Evaluation of the performance and temperature susceptibility of gilsonite-and SBS-modified asphalt binders","volume":"207","author":"Mirzaiyan","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"838","DOI":"10.1080\/14680629.2023.2230294","article-title":"Investigating the properties of asphalt binder modified by high-and low-density polyethylene polymer and nano-silica","volume":"25","author":"Arshadi","year":"2024","journal-title":"Road Mater. Pavement Des."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"141021","DOI":"10.1016\/j.conbuildmat.2025.141021","article-title":"Multi-objective optimization and performance investigation of surface modification synergistic warm-mixed flame retardant asphalt","volume":"473","author":"Sun","year":"2025","journal-title":"Constr. Build. Mater."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"4513824","DOI":"10.1155\/2020\/4513824","article-title":"Evaluating the Physical and Rheological Properties of Rejuvenated Styrene-Butadiene-Styrene-Modified Asphalt Binders","volume":"2020","author":"Chen","year":"2020","journal-title":"Adv. Mater. Sci. Eng."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"130958","DOI":"10.1016\/j.conbuildmat.2023.130958","article-title":"Analysis of rheological behavior and anti-aging properties of SBS modified asphalt incorporating UV absorbent and naphthenic oil (NPO)","volume":"377","author":"Ma","year":"2023","journal-title":"Constr. Build. Mater."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"128","DOI":"10.1080\/14680629.2016.1266754","article-title":"Performance evaluation of REOB-modified asphalt binders and mixtures","volume":"18","author":"Li","year":"2017","journal-title":"Road Mater. Pavement Des."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"124025","DOI":"10.1016\/j.conbuildmat.2021.124025","article-title":"Fatigue performance evaluation of recycled asphalt fine aggregate matrix based on dynamic shear rheometer test","volume":"300","author":"Zhang","year":"2021","journal-title":"Constr. Build. Mater."},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"143315","DOI":"10.1016\/j.conbuildmat.2025.143315","article-title":"Comparative analysis of the fatigue characterisation of natural rock asphalt\/SBS composite modified asphalt binders using time sweep test and linear amplitude sweep test","volume":"494","author":"Xiong","year":"2025","journal-title":"Constr. Build. Mater."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"142544","DOI":"10.1016\/j.conbuildmat.2025.142544","article-title":"Effect of lanthanum oxide and magnesium hydroxide on flame retardancy, rheological properties, and aging resistance of SBS modified asphalt","volume":"490","author":"Tang","year":"2025","journal-title":"Constr. Build. Mater."}],"container-title":["Polymers"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/21\/2829\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,25]],"date-time":"2025-10-25T04:10:57Z","timestamp":1761365457000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2073-4360\/17\/21\/2829"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,10,23]]},"references-count":50,"journal-issue":{"issue":"21","published-online":{"date-parts":[[2025,11]]}},"alternative-id":["polym17212829"],"URL":"https:\/\/doi.org\/10.3390\/polym17212829","relation":{},"ISSN":["2073-4360"],"issn-type":[{"value":"2073-4360","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,10,23]]}}}