【正文】 io (w/b) is mainly credited of availability of super plasticizers and mineral admixtures. The most important design objective of HPC is high durability. According to the whole model of concrete structure, it is the consistency of concrete(viz. no cracks) but not the strength that plays a crucial action on insuring the durability and long life time of concrete structure under service conditions. Due to a higher shrinkage、higher elastic modulus、lower creep and not higher tensile strength, HPC tends to crack at early ages before being put into service. As a consequence, the durability of concrete structure will be degraded.Shrinkage of concrete has been paid much attention all the time because most of cracks of concrete structures, including early age cracking are caused by shrinkage of concrete under restrained condition. Therefore early age shrinkage should be investigated in detail in order to under cracking appears. At present, there is no uniform test stander for measuring shrinkage of concrete at early ages, traditional testing method bees out of condition and some uptodate testing techniques advanced abroad have still some deficiencies. Based on plate specimen, a method to determine restrained shrinkage cracking potential of concrete was proposed. Many experiments showed that most of cracks distributed in the four rim angle field and a cross region formed through connecting each border midpoint when using this method. This distribution from of cracks is related to the restriction condition imposed upon the concrete specimen. The strain distribution is volume of plate specimen was determined through optical fiber sensors, and the results showed that shrinkage strain is approximately an exponential function of distance from drying surface of concrete specimen. As a result, mot only average shrinkage of concrete but also the shrinkage strain distribution and outer restriction condition imposed upon concrete should be considered in analysis of concrete structures. As a whole, the influence of each factor on early cracking potential of concrete is similar to its influence on early age shrinkage.Through the molecule design, a series of novel polycarboxylic acid type waterreducers(MPCs) of various properties with a given structure were prepared by a copolymerization reaction under a certain temperature in a water solution system from the polyethylene glycol unsaturated carboxylic acid ester and other olefin monomers with per sulfate salt as a radical initiator. The waterreducing ratio of the standardtype MPC1 in concrete was % and that of the retardedtype MPC2 was % at the same solid dosage of %. The slump of concretes with such MPCs were maintained without any loss for 12 hours. The properties of MPCs were obviously superior to those of the domestically produced conventional naphthalenebased waterreducers, and slightly inferior to those of the imported polycarbosylic acid type waterreducers as pared samples. The MPCs can be used to prepare highvolume fly ash highflowing concrete, highstrength high performance and highdurability concrete.參 考 文 獻(xiàn)【1】 巴恒靜，[J].工業(yè)建筑，2003，33（8） 【2】 安明喆，覃維祖，[J].山東建材學(xué)院學(xué)報(bào)，199812（51）【3】 ，北京，中國(guó)建筑工業(yè)出版社，1999【4】 ，2001，（2）【5】 郭延輝，趙霄龍，郭京育，：機(jī)械工業(yè)出版社，2004【6】 Polymer technology reshapes water reducers. Concrete Products，1998（10）【7】 ――，1996（2）【8】 游長(zhǎng)江，2003（3）【9】 李崇智，李永德，2002，5（4）【10】，2002（2）【11】 馬一平，,Jun,　2002【12】，建筑技術(shù)，2001（1），【13】 冉千平，游有鯤，2001（12）【14】 ：中國(guó)計(jì)劃出版社，1996【15】 李崇智，李永德，【16】Wiegrink K,Marikunte S, Shah S P, Shrinkage cracking of high strength concrtet, ACI Materials Journal, 1996.【17】Lepage S, Balbaki M, Dallaire E, Early Shrinkage Development in the High Performance Concrete, Cement, Concrete, and Aggregates,1999致 謝 感謝學(xué)部主任王茹博士、李文利教授、王旭鵬教授、陳乃佑教授、徐占發(fā)教授、班主任李雪老師、崔玉璽教授、江輝教授等對(duì)我學(xué)習(xí)上的幫助和指導(dǎo)。 感謝中國(guó)建筑研究院建材研究所趙霄龍博士給我的試驗(yàn)機(jī)會(huì)，同時(shí)還要感謝趙霄龍博士和劉巖博士對(duì)我論文的指導(dǎo)。 感謝北京金宏森建筑公司劉景元總經(jīng)理給我實(shí)習(xí)的機(jī)會(huì)。 感謝爸爸、媽媽對(duì)我的支持的鼓勵(lì)。 感謝我的同學(xué)和身邊的朋友對(duì)我的幫助和支持。第 25 頁(yè) 共 25