超细矿粉对混凝土界面区硫酸盐腐蚀的影响

为了研究骨料与水泥石界面区(ITZ)的组成及结构对混凝土抗硫酸盐腐蚀性能的影响,利用紫外分光光度计绘制了硫酸钠溶液浸泡混凝土试样的SO2-4浸入浓度/深度曲线,并辅以扫描电镜(SEM)和电子探针能谱(EDS)等对ITZ进行观测;同时利用XRD定量分析研究了混凝土本体相和界面相的水化产物富集的差异.结果表明:Ca(OH)2、钙矾石(AFt)等晶体富集于硫酸钠溶液浸泡后试样的ITZ,引起AFt二次结晶型的硫酸盐腐蚀破坏.在适量石膏的激发下,掺入超细矿粉(GGBS)可阻止AFt转变成单硫型水化硫铝酸钙(AFm),减少AFt二次结晶的生成,明显提高抗硫酸盐侵蚀能力,试样的同深度硫酸根浓度最低,抗硫酸盐侵蚀性能最好.     

基于临界钙矾石膨胀破坏的磷石膏基复合胶凝材料的配料计算研究

为制备大掺量磷石膏基复合胶凝材料,在确定主要水化产物类型的基础上,通过计算临界钙矾石膨胀破坏的边界条件,确定各组分最佳掺量范围,研究其对复合胶凝材料力学性能、干缩性能的影响,并通过X射线衍射（XRD）、扫描电镜（SEM）等测试方法研究水化产物的组成及发展规律。研究结果表明：通过理论配料计算,矿粉掺量为50%（质量分数）时,最大磷石膏掺量为26.3%（质量分数）,最小熟料掺量为23.6%（质量分数）。最佳配比组28 d胶砂抗压强度为45.2 MPa,线膨胀率小于0.04%;对比组28 d抗压强度仅有36.4 MPa,线膨胀率远大于0.04%。XRD、SEM表征结果表明,磷石膏基复合胶凝材料的水化产物主要是钙矾石（AFt）和水化硅酸钙（C-S-H）凝胶,氢氧化钙几乎反应完全;对比组钙矾石生成量远大于最佳配料组,微观结构存在大量裂缝。这说明理论配料计算可以有效用于磷石膏基复合胶凝材料的配比优化。     

高性能膨胀剂(CMA)的研究与生产

综合目前国内膨胀剂领域的发展方向和借鉴以往研究成果，采用CaO（钙质熟料）、钙矾石、MgO三个膨胀源的相互作用，三者膨胀适当组合，取长补短，以获得更适宜的膨胀量和膨胀发挥，使膨胀曲线更趋合理。研究了不同掺量不同活性钙质熟料对CMA膨胀剂性能的影响，提出了制备钙质熟料的理化指标，并将CMA与传统膨胀剂的性能进行了对比。     

Investigation on the application of steel slag-fly ash-phosphogypsum solidified material as road base material

The aim of the present work is to prepare a new type of steel slag-fly ash-phosphogypsum solidified material totally composed with solid wastes to be utilized as road base material. The mix formula of this material was optimized, the solidified material with optimal mix formula (fly ash/steel slag=1:1, phosphogypsum dosage=2.5%) results in highest strength. The strength development, resilience modulus and splitting strength of this material were studied comparing with some typical road base materials, the 28- and 360-day strength of this material can reach 8MPa and 12MPa, respectively, its resilience modulus reaches 1987MPa and splitting strength reaches 0.82MPa, it has higher early strength than lime-fly ash and lime-soil road base material, its long-term strength is much higher than cement stabilized granular materials, the solidified material has best water stability among those road base materials, it can be engineered as road base material with competitive properties. The strength formation mechanism of this solidified material is discussed also.     

Q相-C2S-C4AF-C12A7水泥作为膨胀剂的研究

采用普通硅酸盐水泥作为基体、Q相-C2S-C4AF-C12A7水泥作为膨胀剂、加入少量石膏的条件下进行试验研究。研究表明：Q相-C2S-C4AF-C12A7水泥能够作为膨胀组分,调节Q相-C2S-C4AF-C12A7水泥和SO3的量,能够得到所要求的膨胀水泥。从DTA和XRD得知,其膨胀源主要是钙矾石（AFt）,它形成的速度及数量,可以通过控制Q相-C2S-C4AF-C12A7水泥和SO3的量来实现。     

Thermodynamic properties of Portland cement hydrates in the system CaO-Al2O3-SiO2-CaSO4-CaCO3-H2O

A database is presented for commonly-encountered cement substances including C-S-H, Ca(OH)₂, selected AFm, AFt and hydrogarnet compositions as well as solid solutions. The AFm compositions include strätlingite. The data were obtained for the most part from experiment and many of the predicted reactions were confirmed by focussed experiments. The temperature-dependence of the thermodynamic data for the above phases, determined partly from experiment and partly from thermodynamic estimations, are also tabulated in the range 1 °C to 99 °C. Relative to previous databases, sulfate AFm is shown to have a definite range of stability range at 25 °C thus removing long-standing doubts about its stability in normal hydrated cement pastes. Carbonate is shown to interact strongly with stabilisation of AFm across a broad range of temperatures and, at low temperatures, to substitute into AFt. The new database enables the ultimate hydrate mineralogy to be calculated from chemistry: most solid assemblages, the persistence of C-S-H apart, correspond closely to equilibrium. This realisation means that hydrate assemblages can be controlled. The development of a thermodynamic approach also enables a fresh look at how mineralogical changes occur in response to environmentally-conditioned reactions; several papers showing applications are cited.     

粉煤灰对混凝土补偿收缩性能的影响

本文阐述粉煤灰对普通砼和补偿收缩砼的收缩膨胀性能的不同影响 ,指出掺加粉煤灰能使普通砼减少用水量 ,降低收缩值 ,并使补偿收缩砼的膨胀量降低。粉煤灰的火山灰效应对水化产物钙矾石的形貌和性能会产生影响     

Metaettringite, a decomposition product of ettringite

Dehydroxylation of ettringite in an atmosphere of constant partial water vapour pressure (30-400 Torr) and controlled temperature (55-95 °C) yields an X-ray amorphous product containing 11-13 H₂O per ettringite formula unit. The X-ray amorphous product does, however, give electron diffraction patterns similar to those of ettringite but with a considerably reduced from ∼1.123 nm (ettringite) to 0.85 nm in the partially dehydroxylated product, termed metaettringite. The structure of metaettringite is closely related to that of fleischerite, Pb₃Ge[(OH)₆](SO₄)₂·3H₂O and the isostructural despujolsite, Ca₃Mn^IV(SO₄)₂(OH)₆·3H₂O. These minerals contain columnar units. The columnar structure is like that of ettringite but with closer packing of columns in the a direction, resembling metaettringite.The mechanism of collapse of ettringite to metaettringite, involving loss of water and motion of columns, cannot be achieved without scissoring and possibly rotation of individual columns; this and other defect-producing mechanisms result in loss of crystallinity of the metaettringite product.     

CSA水泥作为矿物外加剂对硅酸盐水泥性能及水化的影响

以三种不同粒度的硫铝酸盐水泥(CSA水泥)为矿物外加剂,研究了CSA水泥粒度、掺量对硅酸盐水泥(PC)物理性能、水化过程及水化产物性能的影响.研究表明:CSA水泥的掺量与粒度同时影响PC的凝结时间及标准稠度用水量;当CSA水泥掺量较低(1％)时,PC抗压强度有所提高;CSA水泥缩短PC水化诱导期,促进早期水化,降低C3S的水化速率,加快AFt向AFm转化;CSA水泥增加了早期水泥硬化浆体的孔隙率、累计孔体积及最可几孔径,但对后期硬化浆体的影响不大;而AFt与CH的形貌如短针状AFt及大尺寸六方板状CH不利于晶体的连生与结合,对强度的影响较大.     

Q相-CA-C12A7水泥膨胀性能的研究

本文采用普通硅酸盐水泥作为基体、Q相 CA C1 2 A7水泥作为膨胀剂、加入少量石膏的条件下对该体系的膨胀性能进行试验研究。研究表明 :Q相 CA C1 2 A7水泥能够作为膨胀组分 ,通过调节Q相 CA C1 2 A7水泥和SO3的量 ,得到所要求的膨胀水泥。从DTA和XRD来看 ,其膨胀源主要是钙矾石 (AFt) ,它形成的速度及数量 ,可以通过控制Q相水泥和SO3的量来实现。