Preparation and characterization of metakaolin-phosphate cement

We prepared cold-setting cement with metakaolin from kaolin dehydrated at 800 ℃ and phosphate, and studied the phase composition, microstructure and setting reaction mechanism of the cementing material by means of infrared spectroscopy, thermogravimetry, X-ray diffraction, and scanning electron microscopy. The metakaolin-phosphate cement is predominantly amorphous, where the phases responsible for chemical setting are mainly amorphous aluminophosphate hydrates. The reactivity of metakaolin depends on the particle size. Metakaolin particles of 1.75 μm in D50 have an acid dissolution index up to 18.45%, and the reaction with phosphate at room temperature to form metakaolin-phosphate cement takes only 6 h. The so obtained cement shows a compressive strength of 92.5 MPa after 7 d and keeps its amorphous phase at 1 000 ℃, demonstrating better bonding and mechanical properties and higher stability at a medium or high temperature.     

土聚水泥用高活性偏高岭土的制备

高岭土经-定温度煅烧后,得到的偏高岭土具有较高的火山灰活性,在碱激发剂作用下可制得性能优越的新型胶凝材料--土聚水泥.在煅烧过程中,温度是影响偏高岭土活性的一个至关重要的因素.实验表明,高岭土在700℃煅烧后脱水较完全,其特征峰基本消失,产物经碱激发后所制得的土聚水泥7d抗压强度最高,达到41.3Hpa.因此,700℃下煅烧得到的偏高岭土活性最高.     

Structure characterization for the geopolymer of sodium silicate and metakaolin

1 Introduction 1 During the last decade a new kind of material called geopolymer has emerged as a viable alternative for many conventional cements and plastics. Geopolymer is inorganic polymer derived from metakaolin and sodium silicate solution. It can be synthesized at low temperature and have useful properties such as high compressive strength. It is stable at temperatures up to 800 °C and even 1150 °C while ordinary Portland cement loses its strength at 500 °C [1]. Several microstruct…     

偏高岭土对混凝土应用性能的影响研究

偏高岭土(metakaolin，简称MK)作为矿物掺和料与硅灰(silica fume，简称SF)做对比，试验结果表明，MK是一种良好的矿物掺和料，能显著提高混凝土的强度，完全可以在高性能混凝土中应用．     

掺偏高岭土活性粉末混凝土的结构初探

应用环境扫描电镜等观测手段,对掺偏高岭土活性粉末混凝土(RPC)的内部结构进行初步探讨.偏高岭土等活性矿物掺合料与水泥水化产物所发生的火山灰反应和微粉填充效应,能改善混凝土的孔结构,使混凝土的内部界面区域变得致密和强化,混凝土的物理力学性能得到显著改善.