{"title":"Insights into durability assessment for compacted soils treated with paper sludge ash-based stabilizers","authors":"Navila Tabassum , Ryo Sekine , Kimitoshi Hayano , Binh Nguyen Phan , Hiromoto Yamauchi","doi":"10.1016/j.sandf.2023.101399","DOIUrl":null,"url":null,"abstract":"<div><p>To utilize industrial by-products in construction projects, soil stabilization using paper sludge ash-based stabilizers (PSASs) has recently been developed. PSASs can be manufactured by insolubilizing the heavy metals in original paper sludge (PS) ash, which is a waste product emitted from paper mills. This study assessed the durability of clays treated with PSASs in wet-dry or dry-wet environments through various evaluation tests. Initially, the particle size distributions (PSDs) in the clays that had undergone various pretreatments were assessed. Then, unconfined compression tests were performed on the treated clays that had undergone dry and wet curing cycles using demolded specimens. Finally, cone index tests were carried out on the treated clays that had undergone dry and wet curing cycles while the samples were constrained in molds. Based on the test results, the durability assessment of the clays treated with PSASs was discussed, considering the specifics of each evaluation test and contrasting the findings with those obtained for clays treated with cement. The generated PSDs were found to contain more fine particles as the time spent washing the samples prior to sieving was increased. The findings indicated that PSAS-treated clays will eventually become muddy, even though it is unlikely that these treated clays will ever be subjected to washing with water while being stirred after construction. The unconfined compression test results also demonstrated that, after several dry-wet cycles, the strength of the PSAS-treated specimens had decreased. It was revealed that clays treated with PSASs might be less resistant to dry-wet curing cycles than those treated with cement. However, PSAS-treated samples using unconfined compression test specimens are still being investigated and are a topic of debate because the strength development mechanisms of PSASs and cement are not similar. To address this issue, a series of cone index tests were conducted on samples treated with PSASs<!--> <!-->to examine the change in strength caused by the dry-wet curing process. The results of the cone index tests were different from those of the unconfined compression tests. The cone index test results revealed that the samples must be constrained during the assessment tests in order to assess the durability of PSAS-treated soils subjected to dry-wet curing. In addition, it was proposed in this study that the idea of maturity would be applicable to PSAS-treated soils with a range of curing temperatures and curing times as long as the soils were constrained during the assessment tests.</p></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":null,"pages":null},"PeriodicalIF":3.3000,"publicationDate":"2023-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0038080623001282/pdfft?md5=96345c650963983972dfae12d6972d82&pid=1-s2.0-S0038080623001282-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Soils and Foundations","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0038080623001282","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, GEOLOGICAL","Score":null,"Total":0}
引用次数: 0
Abstract
To utilize industrial by-products in construction projects, soil stabilization using paper sludge ash-based stabilizers (PSASs) has recently been developed. PSASs can be manufactured by insolubilizing the heavy metals in original paper sludge (PS) ash, which is a waste product emitted from paper mills. This study assessed the durability of clays treated with PSASs in wet-dry or dry-wet environments through various evaluation tests. Initially, the particle size distributions (PSDs) in the clays that had undergone various pretreatments were assessed. Then, unconfined compression tests were performed on the treated clays that had undergone dry and wet curing cycles using demolded specimens. Finally, cone index tests were carried out on the treated clays that had undergone dry and wet curing cycles while the samples were constrained in molds. Based on the test results, the durability assessment of the clays treated with PSASs was discussed, considering the specifics of each evaluation test and contrasting the findings with those obtained for clays treated with cement. The generated PSDs were found to contain more fine particles as the time spent washing the samples prior to sieving was increased. The findings indicated that PSAS-treated clays will eventually become muddy, even though it is unlikely that these treated clays will ever be subjected to washing with water while being stirred after construction. The unconfined compression test results also demonstrated that, after several dry-wet cycles, the strength of the PSAS-treated specimens had decreased. It was revealed that clays treated with PSASs might be less resistant to dry-wet curing cycles than those treated with cement. However, PSAS-treated samples using unconfined compression test specimens are still being investigated and are a topic of debate because the strength development mechanisms of PSASs and cement are not similar. To address this issue, a series of cone index tests were conducted on samples treated with PSASs to examine the change in strength caused by the dry-wet curing process. The results of the cone index tests were different from those of the unconfined compression tests. The cone index test results revealed that the samples must be constrained during the assessment tests in order to assess the durability of PSAS-treated soils subjected to dry-wet curing. In addition, it was proposed in this study that the idea of maturity would be applicable to PSAS-treated soils with a range of curing temperatures and curing times as long as the soils were constrained during the assessment tests.
期刊介绍:
Soils and Foundations is one of the leading journals in the field of soil mechanics and geotechnical engineering. It is the official journal of the Japanese Geotechnical Society (JGS)., The journal publishes a variety of original research paper, technical reports, technical notes, as well as the state-of-the-art reports upon invitation by the Editor, in the fields of soil and rock mechanics, geotechnical engineering, and environmental geotechnics. Since the publication of Volume 1, No.1 issue in June 1960, Soils and Foundations will celebrate the 60th anniversary in the year of 2020.
Soils and Foundations welcomes theoretical as well as practical work associated with the aforementioned field(s). Case studies that describe the original and interdisciplinary work applicable to geotechnical engineering are particularly encouraged. Discussions to each of the published articles are also welcomed in order to provide an avenue in which opinions of peers may be fed back or exchanged. In providing latest expertise on a specific topic, one issue out of six per year on average was allocated to include selected papers from the International Symposia which were held in Japan as well as overseas.