{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T17:27:55Z","timestamp":1786123675537,"version":"build-2736575974"},"reference-count":46,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T00:00:00Z","timestamp":1786060800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Guangxi Minzu University","award":["2022KJQD35"],"award-info":[{"award-number":["2022KJQD35"]}]},{"name":"Guangxi Minzu University","award":["2022KJQD26"],"award-info":[{"award-number":["2022KJQD26"]}]},{"award":["2022KJQD35"],"award-info":[{"award-number":["2022KJQD35"]}],"id":[{"id":"https:\/\/ror.org\/0495efn48","id-type":"ROR","asserted-by":"publisher"}]},{"award":["2022KJQD26"],"award-info":[{"award-number":["2022KJQD26"]}],"id":[{"id":"https:\/\/ror.org\/0495efn48","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Guangxi Science and Technology Program","award":["GKFN2600640250"],"award-info":[{"award-number":["GKFN2600640250"]}]},{"name":"Guangxi Zhuang Autonomous Region\u2019s first batch of young talent inclusive support policy research start-up funds","award":["301780206"],"award-info":[{"award-number":["301780206"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Molecules"],"abstract":"<jats:p>Due to the fact that municipal sludge incineration generates a large amount of toxic sewage sludge ash (SSA), cement solidification is becoming an efficient harmless treatment method. However, the large amount of phosphorus in sludge ash can delay the setting time of cement pastes and lead to a decrease in its later strength. Moreover, as an important non-renewable resource, the recycling and utilization of phosphorus is also a current research hotspot. To this end, this paper proposes to remove phosphorus from incinerated sewage sludge ash (ISSA) by the acid washing process, and, in response to the problem of reduced volcanic ash activity in acid-washed sewage sludge ash (ASSA), calcium chloride (CaCl2) is added as an activator to explore the optimal process and hydration mechanism for enhancing ASSA activity. This study removed phosphorus from calcined SSA (800 \u00b0C, 2 h) via acid washing (0.3 mol\/L H2SO4, L\/S = 10:1, 2 h) to obtain ASSA, and used CaCl2 as an activator to improve its pozzolanic activity. Different CaCl2 dosages (1\u20133%) were tested for paste setting time, 3\/7\/28 d compressive strength, and characterized by hydration heat, XRD, SEM, etc. Experimental results indicated that the synergistic addition of 2 wt.% CaCl2 and 20 wt.% ASSA shortened the initial and final setting times by 38% and 23% to 142 min and 289 min, respectively. Meanwhile, the compressive strength at 28 days was improved by 24%, with a final strength value of 42 MPa. Microanalysis revealed abundant Friedel\u2019s salt formation and a denser structure (fine mesopores 60%, coarse mesopores 26%), confirming CaCl2 effectively activates ASSA for cement admixture use.<\/jats:p>","DOI":"10.3390\/molecules31162753","type":"journal-article","created":{"date-parts":[[2026,8,7]],"date-time":"2026-08-07T16:00:43Z","timestamp":1786118443000},"page":"2753","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Calcium Chloride Activation of Acid-Washed Sewage Sludge Ash: Hydration Mechanism and Performance as a Supplementary Cementitious Material"],"prefix":"10.3390","volume":"31","author":[{"given":"Weiwei","family":"Zhu","sequence":"first","affiliation":[{"name":"School of Materials and Environment, Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization, Guangxi Engineering Research Center for Advanced Materials and Intelligent Manufacturing, Guangxi Minzu University, Nanning 530105, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yi","family":"Ren","sequence":"additional","affiliation":[{"name":"School of Materials and Environment, Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization, Guangxi Engineering Research Center for Advanced Materials and Intelligent Manufacturing, Guangxi Minzu University, Nanning 530105, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yaxin","family":"Xiao","sequence":"additional","affiliation":[{"name":"School of Materials and Environment, Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization, Guangxi Engineering Research Center for Advanced Materials and Intelligent Manufacturing, Guangxi Minzu University, Nanning 530105, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shaoyu","family":"Du","sequence":"additional","affiliation":[{"name":"School of Materials and Environment, Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization, Guangxi Engineering Research Center for Advanced Materials and Intelligent Manufacturing, Guangxi Minzu University, Nanning 530105, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3294-157X","authenticated-orcid":false,"given":"Xiaoli","family":"Xie","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Guangxi Polytechnic of Construction, Nanning 530007, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-3651-1358","authenticated-orcid":false,"given":"Kao","family":"Chen","sequence":"additional","affiliation":[{"name":"School of Materials and Environment, Guangxi Key Laboratory of Advanced Structural Materials and Carbon Neutralization, Guangxi Engineering Research Center for Advanced Materials and Intelligent Manufacturing, Guangxi Minzu University, Nanning 530105, China"},{"name":"College of Civil Engineering and Architecture, Guangxi University, Nanning 530004, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"141102","DOI":"10.1016\/j.conbuildmat.2025.141102","article-title":"The effect of sewage sludge ash as a mineral admixture on concrete strength","volume":"475","author":"Tuncer","year":"2025","journal-title":"Constr. 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