{"title":"预测 3D 打印混凝土可建性的挤出窗口和离线测试方法","authors":"Yu-cun Gu, Kamal H. Khayat","doi":"10.1016/j.cemconres.2024.107552","DOIUrl":null,"url":null,"abstract":"<div><p>This study investigates the effect of thixotropy and stiffness evolution on the extrudability and buildability of 3D printing concrete. Different types of supplementary cementitious materials and limestone filler were used to prepare mortars with varying levels of thixotropy and early-age stiffness. Mixtures with yield stress and flocculation (τ<sub>floc</sub>) of 180–400 and 420–950 Pa, respectively, exhibited adequate extrudability without plastic collapse. The printing was completed 8–15 min after mixing at a vertical build-up rate of 138 mm/min. Several process parameters, including rest time to secure a penetration resistance of 150 kPa (T<sub>150</sub>) and penetration resistance at various rest times were developed to assess early-age stiffness. Results indicate that the penetration resistance at rest time of 10–30 min and T<sub>150</sub> can be correlated with the buildable height at elastic buckling. A prediction model of buildable height based on penetration resistance was proposed. The early-age hydration was analyzed to evaluate the early-age stiffness.</p></div>","PeriodicalId":266,"journal":{"name":"Cement and Concrete Research","volume":null,"pages":null},"PeriodicalIF":10.9000,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Extrudability window and offline test methods to predict buildability of 3D printing concrete\",\"authors\":\"Yu-cun Gu, Kamal H. Khayat\",\"doi\":\"10.1016/j.cemconres.2024.107552\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>This study investigates the effect of thixotropy and stiffness evolution on the extrudability and buildability of 3D printing concrete. Different types of supplementary cementitious materials and limestone filler were used to prepare mortars with varying levels of thixotropy and early-age stiffness. Mixtures with yield stress and flocculation (τ<sub>floc</sub>) of 180–400 and 420–950 Pa, respectively, exhibited adequate extrudability without plastic collapse. The printing was completed 8–15 min after mixing at a vertical build-up rate of 138 mm/min. Several process parameters, including rest time to secure a penetration resistance of 150 kPa (T<sub>150</sub>) and penetration resistance at various rest times were developed to assess early-age stiffness. Results indicate that the penetration resistance at rest time of 10–30 min and T<sub>150</sub> can be correlated with the buildable height at elastic buckling. A prediction model of buildable height based on penetration resistance was proposed. The early-age hydration was analyzed to evaluate the early-age stiffness.</p></div>\",\"PeriodicalId\":266,\"journal\":{\"name\":\"Cement and Concrete Research\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":10.9000,\"publicationDate\":\"2024-05-30\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Cement and Concrete Research\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0008884624001339\",\"RegionNum\":1,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"CONSTRUCTION & BUILDING TECHNOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Cement and Concrete Research","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0008884624001339","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CONSTRUCTION & BUILDING TECHNOLOGY","Score":null,"Total":0}
引用次数: 0
摘要
本研究探讨了触变性和刚度演变对 3D 打印混凝土挤出性和施工性的影响。使用不同类型的胶凝辅助材料和石灰石填料制备具有不同触变性和龄期刚度的砂浆。屈服应力和絮凝度(τfloc)分别为 180-400 Pa 和 420-950 Pa 的混合物具有足够的挤出性,不会出现塑性塌陷。混合后 8-15 分钟,以 138 毫米/分钟的垂直堆积速度完成印刷。为评估早期刚度,制定了若干工艺参数,包括确保 150 kPa 穿透阻力(T150)的静置时间和不同静置时间下的穿透阻力。结果表明,10-30 分钟静止时间和 T150 时的穿透阻力可与弹性屈曲时的可构建高度相关联。根据渗透阻力提出了可建高度的预测模型。分析了早期水化情况,以评估早期刚度。
Extrudability window and offline test methods to predict buildability of 3D printing concrete
This study investigates the effect of thixotropy and stiffness evolution on the extrudability and buildability of 3D printing concrete. Different types of supplementary cementitious materials and limestone filler were used to prepare mortars with varying levels of thixotropy and early-age stiffness. Mixtures with yield stress and flocculation (τfloc) of 180–400 and 420–950 Pa, respectively, exhibited adequate extrudability without plastic collapse. The printing was completed 8–15 min after mixing at a vertical build-up rate of 138 mm/min. Several process parameters, including rest time to secure a penetration resistance of 150 kPa (T150) and penetration resistance at various rest times were developed to assess early-age stiffness. Results indicate that the penetration resistance at rest time of 10–30 min and T150 can be correlated with the buildable height at elastic buckling. A prediction model of buildable height based on penetration resistance was proposed. The early-age hydration was analyzed to evaluate the early-age stiffness.
期刊介绍:
Cement and Concrete Research is dedicated to publishing top-notch research on the materials science and engineering of cement, cement composites, mortars, concrete, and related materials incorporating cement or other mineral binders. The journal prioritizes reporting significant findings in research on the properties and performance of cementitious materials. It also covers novel experimental techniques, the latest analytical and modeling methods, examination and diagnosis of actual cement and concrete structures, and the exploration of potential improvements in materials.