硫酸和硫酸钠混合溶液对砂浆的腐蚀作用

用普通硅酸盐水泥和硫铝酸盐水泥的混合水泥以及磨细高炉矿渣和聚合物乳液配制了4种水泥砂浆,研究了这些水泥砂浆试样在1%(质量分数,下同)硫酸加10%硫酸钠的混合溶液中浸泡不同时间后的质量变化和强度变化.结果发现,混合溶液对4种水泥砂浆都具有强烈的腐蚀作用.磨细高炉矿渣能显著提高砂浆的耐腐蚀性能;进一步添加聚合物乳液(聚胶比为10%),则砂浆的抗表面剥落性能有很大改善,其中尤以苯丙乳液与丁苯乳液的混合乳液改性砂浆效果更好,但添加聚合物乳液会导致砂浆的抗压强度大大降低.此外,水泥砂浆试样在混合溶液及清水中浸泡后,它们的抗压强度比值要比它们的抗折强度比值对硫酸/硫酸钠腐蚀介质更为敏感.     

Strength and corrosion properties of Portland cement mortar and concrete with mineral admixtures

This work aims to validate the design assumptions by the California Department of Transportation in order to better define the strategies used to design concrete structures with adequate corrosion mitigation and thus a “maintenance-free” service life. To this end, various laboratory tests were conducted to investigate the compressive strength of and chloride diffusivity in mortar and concrete samples with cement partially replaced by various minerals (class F and class N fly ash, ultra-fine fly ash, silica fume, metakaolin, and ground granulated blast-furnace slag), the porosity of mineral concretes, the freeze–thaw resistance of mineral mortars in the presence of deicers, and the effect of supplementary cementitious materials on the chloride binding and chemistry of the pore solution in mortar.     

The effect of slaked lime,anhydrous gypsum and limestone powder on properties of blast furnace slag cement mortar and concrete

Basic properties of blast furnace slag cement mortar and concrete are investigated by adding inorganic activators. The result of this research concludes that slag cement mixed with suitable activator agents such as lime, gypsum and limestone powder could accelerate the compressive strength and tighten pore structure at early age. The addition of activator into mortar and concrete containing slag cement produces superior properties, reduced shrinkage and less carbonation compared to mortar and concrete containing slag cement without the addition of activator. Consequently, there are possibilities for manufacturing blast furnace slag cement, which could compensate the weak properties at early curing age. When compared with ordinary Portland cement, this cement has superior characteristics for long curing age.     

给水管道水泥砂浆衬里溶出物的安全性评价

为评价水泥砂浆衬里在水环境下金属溶出物的变化情况,考察了砂浆溶出物对饮用水安全性的影响。结果表明,在水泥砂浆与纯水体积比为1：3且长期浸泡的条件下,砂浆存在微量金属元素Fe、Mn、Cu、Zn、Pb、As、Hg、Cr、Cd溶出现象;砂浆在流动自来水、纯水浸泡条件下,溶液的浊度、耗氧量以及Fe、Mn、Cu、Zn的增加量均远低于《生活饮用水输配水设备及防护材料的安全性评价标准》（GB／T17219-1998）限值要求,且没有检测出Pb、Hg、As、Cr、Cd等元素;砂浆衬里表面物相为硅酸盐水化产物、Ca（OH）2、钙钒石和少量石膏,无新的物相产生;石灰石水泥和粉煤灰水泥砂浆溶出物使水的硬度增高,pH值增大的原因是砂浆表面的Ca（OH）2溶解所致;当自来水流量大于20mL/min时,矿渣水泥和矿粉水泥砂浆衬里对水质没有影响。     

利用碱性电解水激发砂浆中矿粉活性的研究

利用碱性电解水制备矿粉砂浆,研究了不同取代率矿粉对砂浆工作性和力学性能的影响,结合XRD分析,评价了利用碱性电解水激发矿粉的活性和改善矿粉砂浆性能的可行性。结果表明:碱性电解水矿粉砂浆的工作性和力学性能均优于自来水矿粉砂浆;当矿粉取代率为20%时,碱性电解水矿粉砂浆的28 d抗折强度和抗压强度较自来水矿粉砂浆分别提高了11.9%和23.5%;碱性电解水矿粉砂浆中存在多钙钾石膏和钾长石,且水化硅酸钙和铝酸钙矿物的衍射峰显著强于自来水矿粉砂浆。     

碱矿渣水泥砂浆抗碳化性能研究

研究了碱当量(以氧化钠当量计)、水胶比和胶砂比对碱矿渣水泥砂浆抗碳化性能的影响,并与硅酸盐水泥砂浆进行了对比试验。结果表明:在相同水胶比条件下,碱矿渣水泥砂浆比硅酸盐水泥砂浆更易碳化,且水胶比越大,胶砂比越小,碳化越严重。在3%～6%范围内,随着碱当量的增加,碱矿渣水泥砂浆的碳化程度减小。扩展度相当时,水玻璃为碱组分的碱矿渣水泥砂浆的抗碳化能力强于硅酸盐水泥砂浆。     

钢渣用作水泥混合材的试验探究

研究了钢渣与矿粉按1∶2、1∶1、2∶1、1∶0掺合的复合粉分别以25%、35%、50%、60%掺入水泥中,对水泥胶砂力学性能的影响,并采用XRD和SEM分析其水化产物。结果表明:随着钢渣掺量的增加,水泥胶砂强度降低,当钢渣掺量超过30%时,强度降低尤为明显,但所配制水泥的技术指标均符合GB/T 175—2007《通用硅酸盐水泥》的技术要求。较钢渣单掺,钢渣与矿粉复掺有利于水泥强度的发展,但大掺量钢渣(60%以上)造成水泥安定性不良。钢渣掺量控制在25%内可以作为混合材应用于水泥生产中。     

Properties of blended sulfoaluminate belite cement

The subject of the study was the possibility of the blending of sulfoaluminate belite (SAB) cement by means of various pozzolanas. The results obtained show that it was possible effectively to modify the properties of SAB cement by means of granulated blast furnace slag, fly ash, and silica fume, and the properties of materials based on these blends. Interesting properties from practical viewpoints of these materials was their compressive strength. As it is very well known, this is by the blending used to decrease. From a viewpoint of the acceptable compressive strength decrease, for SAB cement blends well-found portions of pozzolana with the values of approximately 5–15% seem to be optimal. This range was significantly lower than well-found portions of pozzolanas with values of approximately 20–40% for Ordinary Portland Cement (OPC) blends. The main cause was the fact that unique sources of calcium hydroxide needed for pozzolanic reaction in SAB was only β–C₂S compared to OPC having two sources of calcium hydroxide — the hydration of C₃S and β–C₂S. Therefore, the amount of calcium hydroxide for the pozzolanic reaction in the SAB cement blends was significantly lower. That was why the lower portions of pozzolanas in SAB cement blends were suitable.     

Calcium sulfate hemihydrate activated low heat sulfate resistant cement

Investigations were undertaken to produce low heat sulfate resistant cement by activation of granulated slag obtained from the blast furnace process of iron making and phosphate industries with the calcium sulfate hemihydrate. Experimental data showed that cement gives fast setting characteristics in addition to high strength development. The setting time of cement was regulated with a small addition of set retarder without adversely affecting the strength development of cement. It is noted that beta hemihydrate plaster gives better strength results than the anhydrite activated cement. The results also confirm that granulated blast furnace slag can be replaced with phosphatic slag up to 10% by mass without loosing strength. DTA and X-ray diffraction analysis have been used to identify the hydration products formed in the hydrated cement. The heat of hydration data of cement is reported in the paper.     

聚丙烯纤维抗裂砂浆的试验研究

裂缝是混凝土与砂浆应用中存在的重大问题。不少学者对普通硅酸盐水泥砂浆的收缩裂缝问题进行了大量研究,但纤维的种类、掺入量,以及纤维应当满足的物化性质等尚未形成定论。本文针对加入了脱硫石膏、矿粉等矿物掺合料的普通硅酸盐水泥砂浆,研究了纤维的尺寸、形状及掺入量对砂浆性能的影响。     

Effect of cement type on the resistance of concrete against chloride penetration

In chloride containing environment, chloride permeability of concrete is an important parameter affecting the service life of concrete structures. The primary objective of this experimental study was to study the effect of cement types on the resistance of concrete against chloride penetration for given compressive strength classes. These cements included two different types of granulated blast-furnace slag cement (CEM III/A 32.5N and CEM III/A 42.5N), a sulfate resisting cement (SRC 32.5), and a Portland cement blended with fly ash; all of which compared to an ordinary Portland cement (CEM I 42.5R). For each binder type, four concretes at different strength classes were produced and as a result 20 mixtures were obtained. Rapid chloride ion penetration tests according to ASTM C 1202 were conducted. In addition, electrical resistivity and capillary water absorption tests were carried out. In order to characterize the concrete quality, compressive strength of the specimens were also obtained. The test results clearly demonstrated that the blast-furnace slag cements have the highest resistance against chloride penetration, while the pure Portland cement and sulfate resisting cement have the lowest resistance. Concretes produced with the sulfate resisting cement had substantially higher capillary sorption compared to other mixtures. Test results confirmed the strong relationship between the chloride permeability and electrical resistivity.     

矿物掺合料对硫铝酸盐水泥-普通硅酸盐水泥复合体系性能的影响

研究了矿粉、硅灰和粉煤灰3种矿物掺合料对硫铝酸盐水泥-普通硅酸盐水泥复合体系的标准稠度用水量、凝结时间、水化放热、胶砂抗折及抗压强度、砂浆干缩率、抗硫酸盐侵蚀性能和水化产物的影响。结果表明:随矿物掺合料掺量的增加,复合体系的标准稠度用水量增大,凝结时间延长;掺加矿物掺合料后水化放热峰出现时间延后,总水化放热量减少,其中掺加矿粉和硅灰的试件初期水化速率减慢程度较掺加粉煤灰试件更明显;3种矿物掺合料对复合体系强度的影响差别较大,掺加3%硅灰的试件3 d抗压强度增长较快;硅灰的掺加会使砂浆干缩率增大,矿粉、粉煤灰的掺加可以减小砂浆试件的干缩;矿物掺合料的掺加会提高胶砂试件抗硫酸盐侵蚀性能,掺粉煤灰的试件抗硫酸盐侵蚀性能最好。     

玻化微珠保温砂浆性能影响因素研究

研究了玻化微珠、聚苯颗粒、矿渣、聚丙烯纤维和硬脂酸钙5个组分的掺量及水灰比对玻化微珠保温砂浆性能的影响。试验结果表明:增大水灰比及增加玻化微珠、聚苯颗粒的掺量都会降低保温砂浆的干表观密度及导热系数;水灰比和玻化微珠掺量的增大均会降低保温砂浆的28 d抗压强度;随聚苯颗粒掺量的增加,保温砂浆的28 d抗压强度逐渐提高;增加矿渣和不同长度聚丙烯纤维的掺量,仅在一定范围内提高砂浆的28 d抗压强度;硬脂酸钙能显著降低保温砂浆的吸水率。最佳水灰比为2.1~2.2,玻化微珠、聚苯颗粒、矿渣、聚丙烯纤维(短纤维)和硬脂酸钙的最佳掺量分别为42%~46%、2%、10%、0.1%、2%~4%。     

Basic properties of non-sintering cement using phosphogypsum and waste lime as activator

This study aims to manufacture non-sintering cement (NSC) by adding phosphogypsum (PG) and waste lime (WL) to granulated blast-furnace slag (GBFS) as sulfate and alkali activators. The non-sintering cement’s basic physical and chemical properties are also investigated by evaluating the compressive strength, and the hydrate of NSC. As a result, although the compressive strength is fairly similar to that of ordinary Portland cement (OPC) in the early curing age, it reaches a higher level in the later age than that of OPC due to the continuous reaction of slag and PG. Results obtained from analysis of the hydrate have shown that the glassy films of GBFS are destroyed by the activation of alkali and sulfate, ions eluted from the inside of GBFS react with PG and produce ettringite, and consequently the remaining component in GBFS slowly produced C–S–H(I) gel. Here, PG is considered not only to play the role of simple activator, but also to work as a binder reacting with GBFS.     

新型高效混凝土复合早强剂

本文选用亚硝酸钠、无水硫酸钠、三乙醇胺和聚羧酸减水剂为新型高效复合早强剂的掺料,应用正交实验方法设计实验,从而配置新型高效复合早强剂。实验结果表明,在标准养护条件下,该新型高效复合早强剂可以使得使得水泥试件的1 d强度提高到150%,3 d、7 d、28 d的强度并没有降低;同时,在此基础上,研究该新型高效复合早强剂对复掺矿渣以及粉煤灰水泥强度的影响,结果表明,与不掺粉煤灰以及矿渣的水泥试块相比,当水泥试块的粉煤灰或矿渣的掺量为10%时,该新型高效复合早强剂可以适当的提高胶凝体系的早期强度;但是,当水泥试块的粉煤灰、矿渣掺量为20%及以上时,胶凝体系与空白组相比,抗压强度降低。     

矿渣粉细度与颗粒级配对水泥砂浆性能的影响

主要讨论了不同细度的矿渣粉单掺及复掺后对水泥砂浆强度及微观结构的影响。研究表明,单掺矿渣粉时随矿渣比表面积的增加,砂浆的强度相应增加,但比表面积增加与强度的增加幅度之间并不是简单的线性关系,还得考虑粉体颗粒级配的影响。不同细度的矿渣粉复掺后具有一定的叠合效应,可以使水泥粉体内部颗粒级配趋于合理,从而使得水泥砂浆的强度提高,内部结构变得更加致密。     

Metallurgical slag as a component in blended cement

Metallurgical slags (granulated and air-cooled), are disposed as waste from the ferro-manganese and ferro-manganese–silicon alloys manufacturing plants. They find little use unlike blast furnace slags from steel plants. Investigations were carried out to explore the possibility of using high MnO and low MnO metallurgical slags on samples obtained from an alloy plant in India. Low MnO granulated slag was used in making blended slag cement with ordinary Portland cement (OPC). Addition of slag lowered the compressive strength of the blended cement as compared to that of OPC used. However, the composition of a 50:50 blend, ground to 3000 cm²/g (Blaine), was found to conform to IS 455:1989 for Portland slag cements and also to IS 269:1989, 33 grade OPC, with respect to standard consistency, setting times, soundness and compressive strength (22 MPa at 7 days and 33 MPa at 28 days) tests carried out as per IS 4031:1988. X-Ray diffraction analysis showed that low MnO granulated slag was non-crystalline, whereas the air-cooled slags were crystalline containing mainly quartz, MnO and Mn₂O₃. Chemical analysis showed that the slag samples were low in CaO and Fe₂O₃ contents and high in SiO₂, Al₂O₃, MnO, MgO, Na₂O and K₂O, thus indicating pozzolanic reactions contributing to a great extent in the strength development of blended slag cement compositions studied. High MnO (>15%) and MgO (>8%) containing slags were considered unsuitable for blended cements because of their deleterious effects. Air-cooled lumpy slag was evaluated for use as aggregates in concrete. All the tests were carried out as per IS 2386:1963, methods of test for aggregate for concrete and to conform to IS 383:1990, coarse and fine aggregates from natural resources. The material passed all the tests viz. crushing strength, impact value, abrasion, alkali aggregate soundness, except for deleterious materials content. This slag could be used, with slight modification, for non-structural concrete. The results of the investigations provide a direction for profitable plans for making blended slag cements.     

复合激发剂在磷渣粉干混砂浆中的应用研究

针对磷渣粉高掺量用于水泥干混砂浆时强度低,凝结时间长等缺点,通过采用多种激发剂硫酸钠、消石灰粉、电石渣、磷石膏、脱硫石膏等来激发其活性,并对激发剂的种类和掺量的作用效果进行了研究,确定出最佳配比,达到在干混砂浆中降低水泥用量,提高磷渣资源化利用率的目的。     

除冰盐对碱骨料反应的影响研究

探讨除冰盐及磨细矿渣对含活性骨料砂浆碱骨料反应的影响 ,并对除冰盐的氯离子渗透状况进行了分析。试验结果表明 ,从外部渗透的氯化钠水溶液加速碱骨料反应引起的砂浆膨胀 ,氯化钠水溶液浓度越高 ,膨胀率越大。掺入磨细矿渣能够抑制因除冰盐引起的碱骨料反应的发生     

煤矸石对水泥基材料海水中化学稳定性的影响

通过在人造海水侵蚀液中长期浸泡的试验,研究了煤矸石对水泥砂浆在海水中化学稳定性的影响,并与矿粉和粉煤灰进行了比较.结果表明,煤矸石能明显提高水泥砂浆抗海水化学侵蚀能力,但效果不如矿粉和粉煤灰.掺不同种类掺和料的水泥浆体其孔径的细化是其抗海水化学侵蚀能力提高的根本原因.