粒化高炉矿渣粉在混凝土施工中的应用

结合工程实例,综述了粒化高炉矿渣粉在混凝土施工中的应用,从强度、使用性能、经济效益、社会效益以及混凝土水化热等方面对两种配合比混凝土试验结果进行了对比分析,阐明了该材料的可行性.     

Activation of Algerian slag in mortars

Blastfurnace slag has been widely used as a successful replacement material for Portland cement, and concrete of enhanced qualities can be achieved as a result. Due to the slag’s slow reactivity, however, the early-age mechanical properties may suffer. This paper reports the results of an investigation, carried out at Chlef University (Algeria), using Algerian slag, known to exhibit low reactivity due to its low CaO/SiO₂ ratio. The slag was activated mechanically by grinding the slag to 250, 360 and 420 m²/kg Blaine surface area, thermally by curing mortar specimens at 20°, 40° and 60 °C, and chemically by mixing the slag with two alkalis, NaOH and KOH at different concentrations. Samples were tested for compressive strength at the ages of 1, 3, 7, 28 and 90 days. All three methods enhanced the reactivity of the slag. The results indicated that the slag is very sensitive to temperature rise. Increase in fineness resulted in increased strength development and the fineness of the slag must be greater than that of the cement to achieve better performance. Alkali activation of slag results in increased strength development but the strength was lower than that of the control mortar.     

Investigation of mechanical and mineralogical properties of mortars subjected to sulfate

The durability can be described as concrete’s resistance to the destructive influences of a medium containing acid, sulfate and/or various chemicals and mechanical effects. The main objective of this study is investigation of mechanical and mineralogical properties of cement mortar with different pozzolanic compositions and subjected to sulfated medium. In the study, the mortars produced with cement samples having seven different compositions and varied with an air-entraining agent were subjected to the influence of sulfate. This study is supported by thin section and X-ray powder diffraction (XRPD) investigations, in addition to being subjected to the basic tests, such as compression and flexure. The most important findings obtained from the study are that the compact structure has more effective properties against sulfate effects for cement mortars than pozzolanic materials’ effects and the highest pozzolanic material ratio is restricted about 25–30% by mass because this ratio is a boundary of mechanical properties.     

单氟磷酸钠的阻锈试验研究

采用硬化砂浆法考察了氯离子浓度对钢筋锈蚀性能的影响,并分别对单氟磷酸钠单掺以及单氟磷酸钠与阻锈剂CIA和CIB的1种或2种复掺时的阻锈效果进行了研究.结果表明:未加阻锈剂时,当氯化钠浓度大于1.0%时,钢筋将发生锈蚀:单掺单氟磷酸钠时,阻锈效果随单氟磷酸钠的掺量(0.5%～1.5%)增加而增强,随氯化钠浓度的增大而减弱;阻锈剂复合掺加具有协同作用,即对钢筋的阻锈效果(单氟磷酸钠+CIA+CIB)＞(单氟磷酸钠+CIA)＞(单氟磷酸钠+CIB)＞单氟磷酸钠.     

Durability of copper slag contained concrete exposed to sulfate attack

Sulfate attack is one of several chemical mechanisms of concrete deterioration. Exposure of concrete structures in the sulfate environments may lead to detrimental chemical, microstructural, and physical changes in the concrete matrix, resulting in serious deteriorations and service life reduction. Partial replacement of cement with slag is one of the efficient methods for improving concrete resistance against sulfate attack. In this paper the performance of copper slag contained concrete in sulfate solution is investigated. In this regard, an experimental study including expansion measurements, compressive strength degradation and microstructural analysis were conducted in sulfate solution on concretes made by replacing 0%, 5%, 10% and 15% of cement with copper slag waste. The results of this study emphasized the effectiveness of copper slag replacement in improving the concrete resistance against sulfate attack.     

The durability of masonry mortars made with ladle furnace slag

Ladle furnace basic slag is a by-product of the steelmaking industry. This study examines the properties of masonry mortars made with ladle furnace basic slag and the other conventional components such as sand, cement, and admixtures. Eight different mixes were prepared and the main properties of the resulting mortars were analysed: density, strength, porosity, microstructure and permeability. The porosity of the hardened mixes was studied by means of two complementary techniques: mercury intrusion porosimetry and computerised X-ray tomography. Finally, tests were performed to analyse the behaviour of the mixes exposed to standard detrimental agents such as frost, moisture and sulphates, as well as other special environments, such as saline water or sulphidic atmospheres. The results show that the presence of ladle furnace slag does not damage and even contributes to increasing mortar durability. Its use also decreases or eliminates volumetric contraction during mortar ageing, thereby improving certain masonry applications.     

Durability of concrete pipes subjected to combined steam and carbonation curing

A beneficial use of carbonation as an auxiliary curing regime for concrete pipes was studied in an attempt to reduce steam curing time, improve durability performance and explore the possibility of using concrete pipe to sequester carbon dioxide. Durability performance of the carbonated concretes was characterized by carbon uptake, strength gain, pH, calcium hydroxide content, permeability, sorptivity and sulfate and acid resistance. It was found that initial curing using steam is necessary to facilitate carbonation. Although the contribution of early carbonation to strength gain is not noticeable after initial steam curing, the process is unique in promoting enhanced durability performance of concrete. The early carbonation leads to a reduction in calcium hydroxide near the surface while maintaining a pH above the corrosion threshold value at the core. Carbonated concretes also exhibit improved resistance to sulfate attack, water absorption, and chloride ion penetration. A carbon uptake of 9% by cement mass makes concrete pipe an ideal candidate for carbon dioxide capture and storage.     

基准水泥的选择对矿渣粉活性检测的影响

通过大量试验发现,采用P.O42.5水泥作为基准水泥试验时(用同一种矿渣粉试验样品),矿渣粉的早期活性值要比采用P.I52.5水泥为基准水泥时的早期活性值大很多,3d和7d抗压强度前者比后者高,但28d抗压强度后者却又赶上甚至超过前者。透过此现象,深入分析它的产生机理,为实验单位如何选取基准水泥及基准水泥的生产提供了参考。     

Hydro-abrasive erosion of concrete incorporating ground blast-furnace slag and ground basaltic pumice

In this research work, an attempt has been made to find the suitability of the ground blast-furnace slag (GBS) and ground basaltic pumice (GBP) as a possible substitute for conventional crushed fine aggregate. The main purpose of this investigation is to determine the hydro-abrasive erosion (HAE) characteristics of concrete with GBS and GBP as fine aggregates.The results create perspectives of forecasting HAE of concrete structures depending on the types and amount of additives. It was found that the HAE characteristics of concrete had improved when some of the fine aggregates were replaced by GBS and GBP. As the amount of these additives increased, the mass loss of the concrete incorporating GBS + GBP decreased. This improvement can be explained partly by the decrease in the permeability and partly by the HAE resistance of the additives. In addition to these results, the HAE of concrete was strongly influenced by its compressive strength. Furthermore, the increase in the percentage of additives increased the chloride penetration depths, sharply. The results of this investigation suggest that a joint incorporation of GBS and GBP could conveniently be used to improve its HAE characteristics of concrete.     

Microstructure and durability of mortars modified with medium active blast furnace slag

Mechanical characteristics and durability properties of blast furnace slag cement composites largely depend on the hydraulic activity of the slag. In this paper, a Granulated Blast Furnace Slag with a low reactivity index is used in modifying mortar composition. Microstructure and durability of mixes containing 0%, 30% and 50% of slag as substitution to OPC are respectively compared and analyzed. Water porosity, Mercury Intrusion Porosity and pore size distribution are studied after 28, 90 and 360 days of wet curing. A qualitative microstructure analysis of mortars is proposed with Scanning Electron Microscope (SEM). The durability of mortar is evaluated through capillary water absorption and chloride diffusion tests. The results indicate a finer porosity and lower water absorption for slag mortars at old ages (90 and 360 days). Moreover, lower chloride diffusion for 50% blast furnace slag substitution is observed.     

加矿渣和粉煤灰的混凝土耐久性检测

本文通过现场检测、试验室中混凝土芯样强度与耐久性检测和对检测结果的分析,对某体育场结构混凝土中水泥用量小于《混凝土结构设计规范》GB50010-2002第3．4．2条要求的四种强度等级的混凝土进行了耐久性评价。     

Wet and dry cured compressive strength of concrete containing ground granulated blast-furnace slag

This paper reports a part of an ongoing laboratory investigation in which the compressive strength of ground granulated blast-furnace slag (GGBFS) concrete studied under dry and wet curing conditions. In the study, a total of 45 concretes, including control normal Portland cement (NPC) concrete and GGBFS concrete, were produced with three different water-cement ratios (0.3, 0.4, 0.5), three different cement dosages (350, 400, 450 kg/m³) and four partial GGBFS replacement ratios (20%, 40%, 60%, 80%). A hyperplasticizer was used in concrete at various quantities to provide and keep a constant workability. Twelve cubic samples produced from fresh concrete were de-moulded after a day, then, six cubic samples were cured at 22±2 °C with 65% relative humidity (RH), and the remaining six cubic samples were cured at 22±2 °C with 100%RH until the samples were used for compressive strength measurement at 28 days and three months. Three cubic samples were used for each age and curing conditions. The comparison was made on the basis of compressive strength between GGBFS concrete and NPC concrete. GGBFS concretes were also compared within themselves. The comparisons showed that compressive strength of GGBFS concrete cured at 65%RH was influenced more than that of NPC concrete. It was found that the compressive strength of GGBFS concrete cured at 65%RH was, at average, 15% lower than that of GGBFS concrete cured at 100%RH. The increase in the water-cementitious materials ratios makes the concrete more sensitive to dry curing condition. The influence of dry curing conditions on GGBFS concrete was marked as the replacement ratio of GGBFS increased.     

Some rheological properties of composite slag–cement mortars with secondary industrial waste

The study presents an investigation of rheological properties of mortars made with a new formulation of composite slag–cement for building purpose, which has been patented. The rheokinetics of the initial stages of hydratation process in this cement slurries is studied. The influence of concentration of a new type active additive on the alteration of apparent viscosity of the slag–cement mortar is investigated. It has also been studied the effect of the composition of slag–cement slurry and the change of water–cement ratio on the rheological behavior of it. It is shown, that in relation to concentration the active additive presents a different action on the apparent viscosity. At low concentration it play role as plastification additive, but after a certain concentration considered as threshold it demonstrates an acceleration effect.     

Enhancement of reactivity of calcium hydroxide-activated slag mortars by the addition of barium hydroxide

Sixteen alkali-activated (AA) mortars were mixed and cured at water or air-dried conditions to explore the effectiveness and limitation for the application of barium hydroxide (Ba(OH)₂) as an additional activator in calcium hydroxide (Ca(OH)₂)-activated ground granulated blast-furnace slag (GGBS) system. In order to determine the optimum amount of Ba(OH)₂ that is to be added, test specimens were classified into two series. For series I, the Ca(OH)₂-to-GGBS ratio by weight was 0% and 7.5%, and the Ba(OH)₂-to-GGBS ratio by weight varied from 0% to 10% at a spacing of 2.5% for each Ca(OH)₂-to-GGBS ratio. For series II, the Ca(OH)₂-to-GGBS ratio was 7.5% and 10%, and the Ba(OH)₂-to-GGBS ratio varied up to 3.5%. The flow loss of fresh mortars and the compressive strength development of hardened mortars were measured. In addition, X-ray diffraction (XRD) and energy-dispersive X-ray (EDX) analyses combined with a scanning electron microscope (SEM) image were carried out to ascertain the effect of alkali activators used and the curing condition on the hydration products and the microstructural characteristics of the AA mortars. Test results clearly showed that the water curing condition was more effective than the air-dried curing condition for the formation of the denser calcium silicate hydrate (C–S–H) gels that had a higher molar Si/Ca ratio, resulting in a higher strength development. The addition of 1% Ba(OH)₂ also contributed to the stabilization of C–S–H gels at long-term age, which resulted in a further increase in strength with the increase of age. At the same time, the introduction of Ba(OH)₂ led to the formation of 2CaO·Al₂O₃·SiO₂·8H₂O (C₂ASH₈) hydrates with higher molar Si/Al and Ca/Al ratios. This would also result in a higher strength development of AA mortars tested.     

Durability properties of concrete containing 50% and 65% slag

The method of incorporating slag of normal fineness in concrete has an important bearing on the durability properties of that concrete. In this paper tests are reported to determine some of the durability aspects of concrete containing 50% and 65% of slag replacement, exposed to different curing environments. The mix proportioning of the slag concretes was carried out in such a way that they had low water–binder ratios and high workability, and developed compressive strengths similar to concrete without slag from 3 days onward. The pore size distribution, microstructure and carbonation penetration, as affected by curing regime, of these concrete and their resistance to alkali–silica reaction are reported. The results show that initial water curing of about 7 days prior to exposure to a drying environment is essential to minimise the damage to microstructure that influence the durability of the slag concretes. The data also show that even when exposed to an aggressive environment, slag concretes have a refined pore structure compared to normal concrete, and a better resistance to deterioration.     

大掺量粉煤灰掺合料中超细矿渣的作用

针对大掺量粉煤灰混凝土早期强度低等缺点,提出以部分超细矿渣取代粉煤灰可有效改善其综合性能,对粉煤灰的适宜掺量亦提出建议,并从微观上说明了复合胶凝的优越性。     

Durability analysis of seashore saline soil bound with a slag compound binder

In this paper, a slag compound binder (hereinafter referred to as the SM binder) was used to bind seashore saline soil. Compressive tests, scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction analytical tests were carried out to measure the unconfined compressive strength, observe the microstructure, analyze the composition of hydration products and evaluate the binding mechanism of the saline soil/SM binder mixture. The results showed that calcium silicate and calcium aluminate hydrates were produced after the hydration of the cinder components in the SM binder. Part of the calcium aluminate hydrate reacted with the gypsum to form ettringite, while the other part reacted with the Cl^? and SO₄^2? in the saline soil to produce Kuzel’s salt. Na⁺ also participated in the hydration reaction and produced zeolite-like substances. These hydration reactions led to the rapid binding of the soil sample. As the surface of the saline soil particles also contained active SiO₂ and A1₂O₃, the Ca(OH)₂ reacted with them to form calcium silicate and calcium aluminate hydrates in a continuously alkaline environment. Such reactions contributed to the third-stage binding of the saline soil, leading to a gradual increase in the strength of the soil samples during the middle and late stages of binding.     

Multi-surface model application to beam-columns subjected to cyclic loads

This paper deals with an analytical study of the cyclic behaviour of structural members by employing a multi-surface model for material nonlinearity. Extensive numerical studies of tubular beam-columns have been performed with the special stress-strain relationship of cold-formed material. These numerical results are compared with test results by Sherman. It can be concluded from the present study that (i) the multi-surface model based on a special stress-strain relation for the cold-formed material gives excellent agreement with the experimental results by Sherman, for investigation of the cyclic behaviour of tubular beam-columns and (ii) the multi-surface model is suitable for analyses of structural members in general and cold-formed tubular beam-columns in particular, under cyclic loading conditions.     

石蜡相变储能砂浆应用性能研究

相变控温储能材料可机敏控制混凝土结构温度裂缝,对石蜡相变砂浆的应用性能进行了研究。采用石蜡颗粒和石蜡乳液作相变材料配制相变储能砂浆,测试了相变储能砂浆的和易性能、不同龄期的抗折强度和抗压强度以及变形性能,并采用压汞法测试其微观孔结构。试验结果表明:石蜡乳液相变砂浆变形性能优于石蜡颗粒相变砂浆,但石蜡颗粒相变砂浆的和易性和强度均优于石蜡乳液相变砂浆,且石蜡颗粒相变砂浆的孔隙率小、孔结构更合理。     

硫酸钠激发超细矿粉的性能研究

碱激发材料因其低碳排放特性受到广泛关注。为了克服硫酸钠激发矿粉体系抗压强度发展缓慢的缺陷,本文通过降低矿粉粒径,提高硫酸钠对矿粉的激发效率,实现增强抗压强度的效果。结果表明,在常温条件下,中值粒径为4.3μm的矿粉被9%的硫酸钠激发后,胶砂的28d和90d抗压强度可达到44MPa和71.8MPa。