利用含碳量高、火山灰活性较低的堆存粉煤灰为原料,用水热合成-低温煅烧方法制备粉煤灰贝利特水泥,研究了配合料CaO掺量与在97℃ ±2℃下的蒸养时间、煅烧温度和煅烧时间对前驱物和粉煤灰贝利特水泥的组成及其基本物理力学性能的影响.结果表明:在97℃ ±2℃蒸养和800℃煅烧,粉煤灰中的莫来石和石英几乎不与CaO发生反应;800℃煅烧的粉煤灰贝利特水泥熟料中主要水硬性矿物为α'L-C2 S和C12 A7,当煅烧温度达900℃或更高时,贝利特以活性较低的β-C2 S存在,并且熟料中有水化活性很低的钙铝黄长石形成.CaO掺量为30％ 的石灰-粉煤灰配合料在97℃蒸养10 h后经800℃煅烧1 h,制得28 d抗压强度达到30.2 M Pa的粉煤灰贝利特水泥.粉煤灰贝利特水泥凝结快,可用于快修工程,但其需水量大,硬化浆体结构相对疏松,孔隙率较大.%Stockpiled fly ash with high carbon-content and low reactivity was used to prepare belite cement by hydrothermal treatment followed by low temperature calcination .The effects of CaO content of starting mixture ,hydrothermal treatment time at 97℃ ± 2 ℃ ,calcination temperature and durating time on the composition of the precursor and clinker ,and on the properties of the fly ash belite cement were investigated .The results show that the mullite and quartz in fly ash nearly do not take part in the reactions during hydrothermal treatment at 97 ℃ ± 2 ℃ and calcination at 800 ℃ .The main hydraulic minerals in the belite cement clinker areα'L-C2 S and C12 A7 when the clinker was calcined at 800 ℃ ,whileβ-C2 S and gehlenite exist when the clinker was calcined at 900 ℃or higher temperature .Fly ash belite cement with the compressive strength as high as 30.2 MPa at 28 d was prepared from mixture with the CaO content of 30％ ,by hydrothermal treatment at 97 ℃ for 10 h followed by calcination at 800 ℃ for 1 h .Fly ash belite cement is characterized by rapid setting ,which makes it suitable for rush-repairing project ,however ,high water requirement which result in looser microstructure and higher porosity of the hardened cement paste .
展开▼
