蒸馏法测定水泥及原料中的氟和氯

水泥工业中已广泛采用以萤石 (氟化钙 )作矿化剂。其中氟化钙的加入量对水泥熟料的煅烧工艺和水泥的物理性能都有很大影响,为此水泥企业都很重视氟含量的测定。 随着我国水泥工艺中窑外分解技术的广泛应用,对水泥原料中氯含量的控制显得尤为重要。根据生产工艺要求,生料中的氯含量不大于 0 015％,否则将影响生产。另外水泥中氯含量偏高,也可能引起混凝土中的钢筋锈蚀问题。     

利用水泥窑灰和粒化高炉矿渣制备生态水泥

当前窑灰的利用率低下。为探索用立窑或流态化床水泥窑系统煅烧窑灰，制备生态水泥的可能性，对不同硫、碱含量窑灰以及加入复合矿化剂的生料进行了易烧性实验、TG—DTA分析、高温显微分析，窑灰熟料的XRD分析，研究了窑灰生态水泥熟料的烧成性能以及矿物组成，对比了窑灰矿渣生态水泥和矿渣硅酸盐水泥的抗压强度。结果表明：窑灰加入氟硫复合矿化剂煅烧后的熟料，掺入40％矿渣可制成强度与32．5级矿渣水泥相当的生态水泥。     

石膏作为矾土水泥熟料矿化剂的初步探讨

一般认为,在水泥生料中加入矿化剂的作用,是加速矿物的形成过程,并能降低水泥熟料的煅烧温度。例如以萤石作为硅酸盐水泥熟料的矿化剂已被广泛应用在工厂的生产中。然而,关于矾土水泥熟料矿化剂的研究还很少。现将我们用石膏作为矾土水泥熟料矿化剂的初步研究结果介绍于下,供各兄弟单位参考。     

锅炉炉渣、铅锌尾矿渣等废渣的利用

介绍了用锅炉炉渣、铅锌尾矿渣代替粘土、铁粉及矿化剂配制生料的效果，强调了应用废弃物配料烧制硅酸盐熟料需采取的工艺措施。生产实践表明，用锅炉炉渣、铅锌尾矿渣、磷渣、粉煤灰作原材料(混合材)可生产出价低质优的普通水泥，能获得较好的经济效益和社会效益。     

利用石英尾砂和柠檬酸废渣石膏生产水泥的研究及实践

对石英尾砂和柠檬酸废渣石膏在水泥生产中的资源化利用进行了实验室研究和实际生产试验。研究结果表明,石英尾砂掺量占生料的2．5％～5．0％,以及柠檬酸废渣石膏作矿化剂掺量占生料的20％～30％范围时,可有效改善生料的易磨性和易烧性,生产出强度较高的水泥熟料。     

化纤工业污泥用于水泥生产的初步研究

以不同温度烘干和煅烧处理山东某化纤工厂的化纤污泥,并对该污泥处理样进行了EDS和XRD分析;然后将预处理后的化纤污泥作为矿化剂制得硅酸盐水泥。相关测试结果表明:(1)处理后的化纤污泥可以代替磷石膏作硅酸盐水泥矿化剂;(2)同一温度下,污泥作矿化剂配制的硅酸盐水泥生料易烧性要比磷石膏作矿化剂配制硅酸盐水泥生料的好。     

磷石膏的复合矿化作用及其对硅酸盐水泥生料煅烧的影响

通过易烧性、正交实验和XRD分析,研究了磷石膏的复合矿化作用及其对硅酸盐水泥生料煅烧的影响,并对KH、复合矿化剂与熔剂组分配比和煅烧温度与硅酸盐水泥生料易烧性及SO2挥发量的关系进行了探索.结果表明：磷石膏具有复合矿化作用,可改善硅酸盐水泥生料煅烧,促进固相反应;磷石膏2.0%和矿渣2.0%作复合矿化剂,不仅可促进水泥生料的煅烧,而且减少SO2挥发,既有利于工业固体废物的资源化利用,又有利于生态环境的保护.     

复合矿化剂低温煅烧硅酸盐水泥熟料技术

叙述了低温烧成熟料的矿物组成和物理性能;叙述了硅酸盐水泥、普通水泥、矿渣水泥、快硬水泥、无收缩快硬水泥的物理性能;介绍了复合矿化剂低温煅烧硅酸盐水泥熟料技术的社会经济效益;讨论了复合矿化剂低温煅烧的机理和大大提高高碱熟料强度的机理。     

提高立窑水泥质量的技术措施

我厂的生料磨，水泥磨都是Φ2．2m*6.5m带离心式选粉机的闭路系统，立窑规格是直径2．9m*10m和直径2．5m*10m盘塔式机立窑各1台，熟料月平均标号稳定在59．5－62．5MPa，主导产品425号复合硅酸盐水泥一等吕率达到80％以上，525号普通硅酸盐水泥一等吕率达100％，实施ISO水泥强度检验法后，熟料3d和28d抗压强度分别吓降5－7Mpa和7－12MPa抗折强度分别下降0．5－1．0MPa，和0．5MP,a为此，我厂主要从以下几方面采取措施。     

高硅酸盐水泥熟料煅烧的试验研究

本文从生料易烧性人手,研究了氟硫复合矿化剂对高硅酸盐矿物含量水泥熟料煅烧的影响.利用XRD及XRF对易烧性较好且C3S含量较高的熟料进行了矿物组成及硫含量分析.研究结果表明:在添加氟硫复合矿化剂的条件下可煅烧获得硅酸盐矿物含量大于90％且C3S含量大于70％的高硅酸盐水泥熟料.熟料中f-CaO含量随饱和比LAD的增加而增加,随助溶剂量QLP的增加逐渐减少,随硫过量系数EC的增加而略微升高.熟料中的主要矿物C3S和C2S形成情况良好.     

掺Ⅱ级粉煤灰高性能混凝土在短龄期养护条件下的抗侵蚀性能初讨

按高性能混凝土配比方法配制不同掺量的Ⅱ级粉煤灰胶砂试件,分别与普通水泥胶砂试件和高抗硫酸盐水泥胶砂试件进行抗硫酸盐侵蚀的对比试验。试验结果发现,在短龄期养护条件下,经过高浓度硫酸盐溶液的侵蚀浸泡,不掺粉煤灰的普通胶砂试件和高抗硫水泥胶砂试件的抗蚀系数随侵蚀浸泡时间下降很快,在较短时间内就丧失了抗蚀能力;而掺有Ⅱ级粉煤灰的胶砂试件则维持较高的抗蚀系数,特别当Ⅱ级粉煤灰掺量达到60%时,其抵抗高浓度侵蚀溶液侵蚀的效果显著。     

Alternative blended cement with ceramic residues: Corrosion resistance investigation on reinforced mortar

Blended cements are largely used for concrete: they are usually considered cements with a low environmental impact, as they require less clinker than ordinary Portland cement (OPC). Different constituents can be used as supplementary clinker component usually leading to cement with high resistance to outdoor environment. Polishing residue (PR), coming from porcelain stoneware tiles production, can be successfully used as new constituent for blended cement, however its action for enhancing the durability of cement matrix must be assessed. With this purpose, electrochemical tests (half cell potential, impressed voltage and linear polarization techniques) have been carried out on steel reinforced mortar samples, prepared using a 25% PR based cement and 100% OPC as binder and exposed to a 3.5% NaCl solution. The corrosion resistance results and microstructure analysis highlight better durability performances for PR based cement than those exhibited by OPC, mainly for curing time > 28 days.     

Superplasticized portland cement: production and compressive strength of mortars and concrete

This paper deals with the effect of intergrinding different percentages of a naphthalene-based superplasticizer with Portland cement clinker and gypsum on the fineness of the product, and on the water requirement and the compressive strength of the mortars made with the superplasticized cement. The properties of the fresh and hardened concrete made with the superplasticized cements were also investigated. The results showed that the intergrinding of a given amount of a naphthalene-based superplasticizer with Portland clinker and gypsum reduced the grinding time required for obtaining the same Blaine fineness as that of the control Portland cement without the superplasticizer. The water requirement of the mortars made with the superplasticized cements was similar to that of the mortars made with the control Portland cements when the same amount of the superplasticizer was added at the mortar mixer; for a given grinding time and a Blaine fineness of 4500 cm²/g, the mortars made with the superplasticized cement had higher compressive strength than those made with the control Portland cement. For a given grinding time or Blaine fineness of cement ≥5000 cm²/g, the slump loss, air content stability, bleeding, autogenous temperature rise, setting times, and compressive strength of the concrete made with the superplasticized cements were generally comparable to those of the concrete made with the control Portland cements when the superplasticizer was added at the concrete mixer.     

垃圾焚烧飞灰煅烧阿利尼特水泥熟料的形成过程及其水化性能研究

以城市垃圾焚烧飞灰(以下简称焚烧飞灰)为主要原料,在实验室电炉里成功研制了阿利尼特水泥熟料。本文主要研究水泥熟料煅烧形成过程及其水化性能,分析了阿利尼特水泥的适宜石膏掺量、水化放热特征、水化产物及其显微结构。研究结果表明:利用垃圾焚烧飞灰为主要原料可以成功烧制阿利尼特水泥熟料,煅烧过程中首先出现C2S、C12A7和C2S·CaCl2,随后与MgO和CaCl2反应生成阿利尼特;掺加5%二水石膏可以促进阿利尼特水泥水化,较普通硅酸盐水泥更快,阿利尼特水泥可以作为一种早强快硬型水泥使用;阿利尼特水泥主要水化产物除含有硅酸盐水泥中常见的CSH凝胶、棒状AFt和Ca(OH)2晶体外,还含有C3A·CaCl·210H2O晶体。     

Setting and hardening of borogypsum-Portland cement clinker-fly ash blends. Studies on effects of molasses on properties of mortar containing borogypsum

The present work describes a study of setting and hardening of blends of borogypsum, fly ash, and Portland cement clinker (PC). The possibility of using borogypsum instead of natural gypsum in fly ash-cement matrix has been investigated through several tests. In addition, the effects of molasses on the setting times of cement and strength of the mortar were also studied. The setting times of the cement were retarded when the natural gypsum was replaced by borogypsum. Molasses exhibited a rather significant retarding effect when used in combination with borogypsum in cement. The inclusion of molasses to the system at a level of 0.1% resulted in a reduction in early strength of the mortar. However, it significantly enhanced the strength of the mortar after 7 days of curing age. In general, the cement prepared with borogypsum was found to have similar strength properties to those obtained with natural gypsum, and inclusion of molasses into the system significantly increased the strength of the sample after 7 days of curing age.     

海工水泥原料组成的优化试验研究*

根据国家标准对海工水泥原材料组成的要求,本文以粉煤灰、矿粉、硅灰为混合材与硅酸盐水泥熟料、石膏复合,通过水泥砂浆物理性能试验、抗渗性能试验、抗硫酸盐侵蚀试验和混凝土氯离子扩散系数试验,优化、确定了海工水泥合理的原材料组成范围。试验结果表明,当熟料掺量≥33%,硅灰掺量≤3%时,所制备的海工水泥的力学性能满足国家标准42.5级海工水泥的要求;以33%的熟料、7%的石膏、17%的粉煤灰、40%的矿粉和3%的硅灰制备的海工水泥具有较好的早期、后期强度和良好的耐久性能。XRD和SEM分析结果表明,与普通硅酸盐水泥相比,海工水泥水化体系中AFt含量多,可提高水泥石的致密度,减小孔隙率,使水泥硬化体具有优异的力学性能和耐久性能。     

Portland cement clinker, granulated slag and by-pass cement dust composites

Three blends of slag cement were prepared, namely 70/30, 50/50 and 30/70 mass% of Portland cement clinker and granulated slag, respectively. Each blend was mixed with 2.5, 5.0, 7.5 and 10.0 mass% by-pass cement dust. The physical properties of cement pastes were studied, including setting times, electrical conductivity and fluidity. The results indicated that the rheological properties of Portland cement clinker were enhanced by partial replacement by granulated slag. By-pass cement dust affects the rheological properties of Portland cement clinker/granulated slag composites and depends on its amount as well as mix composition. The increase in the amount of by-pass cement dust increases the required water of normal consistency. The setting time of Portland slag cement paste was extended with the increase in slag content. The addition of 2.5 mass% by-pass cement dust to M.1 (70 mass% Portland cement clinker/30 mass% granulated slag) and M.2 (50 mass% Portland cement clinker/50 mass% granulated slag) retards the initial and final setting time, whereas it accelerates the final setting time of M.3 (30 mass% Portland cement clinker/70 mass% granulated slag). The presence of by-pass cement dust affects the location and height of the conductivity peaks. By increasing the by-pass cement dust from 2.5 to 7.5 mass%, the conductivity maximum increases. With further addition (10.0 mass%), the height of the conductivity maximum decreases.     

熟料和粉煤灰的颗粒尺寸分布与水泥性能的灰色关联分析

将不同比表面积的熟料和粉煤灰分别混合制得不同比表面积的粉煤灰水泥,分别测定粉煤灰水泥胶砂强度和熟料、粉煤灰的颗粒尺寸分布.运用灰色系统原理分别就熟料和粉煤灰的颗粒尺寸分布对水泥强度的影响进行数学分析.研究表明:熟料颗粒粒径在0～30 μm为正关联,>30 μm为负关联,其中10～20 μm颗粒对水泥强度的影响最大;粉煤灰颗粒粒径在0～40 μm为正关联,且其活性较高,>40 μm颗粒为负关联,其活性没有得到充分发挥.     

Prediction of later-age compressive strength of normal concrete based on the accelerated strength of concrete cured with microwave energy

Microwave energy can accelerate the hydration of cement, resulting in rapid strength development of concrete in an early period. In this paper, prediction of later-age compressive strength of normal concrete, made with rapid-hardening and ordinary Portland cement, based on the accelerated strength of concrete cured with microwave energy was investigated. To accelerate curing properly, the optimal microwave curing process for concrete was first determined and then was applied to concrete. The possible early ages for the strength prediction were found to be at 3.5 and 5.5 h for concrete made with rapid-hardening and ordinary Portland cement, respectively. For each cement type, a formula for the strength prediction was derived from the relationship between accelerated early-age strength of concrete cured with microwave energy and later-age strength of normally cured concrete. Predictions of strength at 7 days for concrete made with rapid-hardening Portland cement and 28 days of concrete made with ordinary Portland cement were within 15% agreement with actual test results.     

Effect of curing conditions on the total water content of hardened portland cement paste

The effect of various curing conditions on the amount of water held by pastes with low water/cement ratios was investigated. It was concluded from the results that factors significantly influencing the total water content of a cement paste made with ordinary Portland cement and cured at room temperature are: water/cement ratio, curing medium, curing period and curing history.