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C120超高泵送机制砂自密实混凝土研制
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作者 王贵禄 陈尚伟 +2 位作者 何信周 陈燕菲 严龙顺 《建筑技术》 2024年第3期354-358,共5页
为满足机制砂混凝土的超高强与超高泵送性能需求,开展超高泵送超高强机制砂自密实混凝土制备技术研究,研制的C120机制砂自密实混凝土坍落度达270 mm、扩展度达730 mm、倒置坍落度筒时间为3.2 s,水化温升峰值温度小于80℃,28 d抗压强度高... 为满足机制砂混凝土的超高强与超高泵送性能需求,开展超高泵送超高强机制砂自密实混凝土制备技术研究,研制的C120机制砂自密实混凝土坍落度达270 mm、扩展度达730 mm、倒置坍落度筒时间为3.2 s,水化温升峰值温度小于80℃,28 d抗压强度高达127.3 MPa、电通量小于500 C,最大收缩低于4×10^(-8) m。研制的C120机制砂自密实混凝土在贵阳国际金融中心成功应用,一次性垂直泵送401 m,在泵送过程中未发生堵管等事故,钻取的芯样完整。另外,现场留样的混凝土和钻取的芯样28 d抗压强度均满足大于120 MPa的性能要求。 展开更多
关键词 C120 机制砂 超高强混凝土 超高泵送 工程应用
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Characterization of Soil Available Nitrogen in the Major Vegetable Production Areas of Pearl River Delta,China 被引量:7
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作者 CHEN Qiong-xian ZHANG Bai-ge +6 位作者 CAO Jian he xin-zhou FAN Mei-hong GAO Hui-nan YAGN Qiu LI Qiang CHEN Han-cai 《Agricultural Science & Technology》 CAS 2010年第7期99-102,共4页
A macro scale survey was performed to investigate the content of soil available nitrogen (N) and its spatial distribution in the main vegetable production areas of the Pearl River Delta.Preliminary enrichment-deficien... A macro scale survey was performed to investigate the content of soil available nitrogen (N) and its spatial distribution in the main vegetable production areas of the Pearl River Delta.Preliminary enrichment-deficient index of available N was then developed,which was a base for increasing fertilizer application efficiency and vegetable yield as well as for constructing soil testing and fertilizing formula.In general,most of the vegetable growth areas in Pearl River Delta were N-deficient or medium-N-deficient.There was 30%-62% increase in yield of Chinese cabbage on the N-deficient soil after application of N; when soil available N content was less than 145 mg/kg,the yield increased with application of N fertilizer at a rate of 60-70 kg/hm2. 展开更多
关键词 珠江三角洲地区 土壤速效氮 蔬菜生产 表征 产区 中国 蔬菜产量 测土配方施肥
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