钢渣微珠替代细骨料对不同等级混凝土力学性能的影响

钢渣微珠是将液态钢渣直接气淬而成的钢渣副产品,粒度均匀,稳定性好。将钢渣微珠作为混凝土细骨料替代品,研究了不同钢渣微珠细骨料替代率(0、20%、35%、50%)对C30和C50混凝土力学性能的影响。结果表明:钢渣微珠替代细骨料后,对C30混凝土抗压强度和抗折强度的提高有促进作用,但对C50混凝土抗压强度和抗折强度有反作用;随着钢渣微珠替代率的增大,混凝土抗拉强度呈现先增大后降低趋势,C30、C50抗拉强度分别在钢渣微珠替代率为35%、25%时达到最大值3.25、3.44 MPa;钢渣微珠适宜应用在较低等级混凝土中,在C30混凝土中替代率为20%~35%较佳。     

Performance of high strength concrete made with copper slag as a fine aggregate

This research study was conducted to investigate the performance of high strength concrete (HSC) made with copper slag as a fine aggregate at constant workability and to study the effect of superplasticizer addition on the properties of HSC made with copper slag. Two series of concrete mixtures were prepared with different proportions of copper slag. The first series consisted of six concrete mixtures prepared with different proportions of copper slag at constant workability. The water content was adjusted in each mixture in order to achieve the same workability as that for the control mixture. Twelve concrete mixtures were prepared in the second series. Only the first mixture was prepared using superplasticizer whereas the other eleven mixtures were prepared without using superplasticizer and with different proportions of copper slag used as sand replacement. The results indicated that the water demand reduced by almost 22% at 100% copper slag replacement compared to the control mixture. The strength and durability of HSC were generally improved with the increase of copper slag content in the concrete mixture. However, the strength and durability characteristics of HSC were adversely affected by the absence of the superplasticizer from the concrete paste despite the improvement in the concrete strength with the increase of copper content. All concrete mixtures did not meet the strength and durability design requirements due to the segregation and dryness of the concrete paste. Therefore it can be concluded that the use of copper slag as sand substitution improves HSC strength and durability characteristics at same workability while superplasticizer is very important ingredient in HSC made with copper slag in order to provide good workability and better consistency for the concrete matrix.     

Durability of concrete incorporating non-ground blast furnace slag and bottom ash as fine aggregate

The paper presents investigation of how the usage of bottom ash (BA), granulated blast furnace slag (GBFS), and combination of both of these materials as fine aggregate in concrete affects the concrete durability. To assess durability characteristics of concrete, durability tests were conducted and the results were evaluated comparing with reference concrete. Three series concrete were produced. GBFS, BA and GBFS+BA are replaced the 3–7 mm-sized aggregate. Five test groups were constituted with the replacement percentages as 10%, 20%, 30%, 40% and 50% in each series. These by-products were used as non-ground form in the concrete. Durability properties of the concretes were compared in order to study the possible advantages of different replacement ratios. According to results, GBFS and BA affects some durability properties of concrete positively in case of it is used as fine aggregate. Resistance to high temperature and surface abrasion are positively affected properties. Capillarity, drying-wetting and freezing-thawing resistance of the concrete can be accepted to some extent. Properties of by-products and its replacement ratio are controlling the influence level and direction. Comparison of the SEM images and test results show that chemical and physical properties of GBFS and BA are the main factors affecting the concrete durability. It is concluded that it is possible to produce durable concrete by using GBFS and BA as fine aggregate.     

钢渣细集料安定性测定方法研究

钢渣细集料具有密度大、强度高、抗渗性好等优点而大量应用于建材行业。安定性是决定钢渣制品能否工程推广的关键因素,因此有必要寻找合适的安定性测定方法,准确检测其安定性。通过开展多种试验方法进行钢渣细集料安定性的测试研究,结果表明压蒸法测定强度变化是比较可靠的安定性检测方法。     

钢渣替代粗骨料配制混凝土的试验研究

本试验用钢渣等体积替代石子配制钢渣混凝土,并与同强度等级的普通混凝土的力学性能进行对比,试验结果表明,钢渣混凝土的抗压强度明显优于普通混凝土,但由于钢渣中含有大量的游离CaO,钢渣混凝土试块在水中养护中发生了爆裂现象。     

钢渣细集料在混凝土路面中的应用研究

钢渣细集料 复合矿渣微粉作为混凝土的胶结材，按照水泥胶砂强度的检验方法，测定胶结材强度，配制路面施工混凝土，进行胶结材与水泥对比性能试验，观察其水化及微观结构，分析钢渣细集料界面反应状况，验证路面质量。     

铬渣作为细集料的材料性能及应用探究

通过对包头某铬渣厂的新老铬渣作为细集料的基本材料性能进行试验探究,并加入不同掺量的新老铬渣做成水泥固化铬渣试块测试其3、28 d的抗压抗折强度,证实解毒后的铬渣具有作为公路水泥混凝土的细集料的可能性。     

Effect of copper slag as a fine aggregate on the properties of cement mortars and concrete

An experimental investigation was conducted to study the effect of using copper slag as a fine aggregate on the properties of cement mortars and concrete. Various mortar and concrete mixtures were prepared with different proportions of copper slag ranging from 0% (for the control mixture) to 100% as fine aggregates replacement. Cement mortar mixtures were evaluated for compressive strength, whereas concrete mixtures were evaluated for workability, density, compressive strength, tensile strength, flexural strength and durability. The results obtained for cement mortars revealed that all mixtures with different copper slag proportions yielded comparable or higher compressive strength than that of the control mixture. Also, there was more than 70% improvement in the compressive strength of mortars with 50% copper slag substitution in comparison with the control mixture. The results obtained for concrete indicated that there is a slight increase in density of nearly 5% as copper slag content increases, whereas the workability increased significantly as copper slag percentage increased compared with the control mixture. A substitution of up to 40–50% copper slag as a sand replacement yielded comparable strength to that of the control mixture. However, addition of more copper slag resulted in strength reduction due to the increase in the free water content in the mix. Also, the results demonstrated that surface water absorption decreased as copper slag content increases up to 50% replacement. Beyond that, the absorption rate increased rapidly and the percentage volume of the permeable voids was comparable to the control mixture. Therefore, it is recommended that up to 40–50% (by weight of sand) of copper slag can be used as a replacement for fine aggregates in order to obtain a concrete with good strength and durability requirements.     

生活垃圾焚烧灰渣代砂混凝土配合比及力学性能试验

对生活垃圾焚烧灰渣代砂作为混凝土细骨料进行了试验研究。从有毒物质浸出、筛分、压碎指标等分析了生活焚烧垃圾灰渣的骨料特性,并对5种水胶比、3种代砂率的生活垃圾焚烧灰渣细骨料混凝土进行了配合比试验及力学性能试验。试验结果表明,生活垃圾焚烧灰渣多孔、吸水率高、压碎指标低,具有一定的潜在水硬性;通过增加减水剂等合理配合比设计,可以配出工作性能满足工程要求的生活垃圾焚烧灰渣细骨料混凝土;生活垃圾焚烧灰渣细骨料混凝土强度要低于同配合比条件的普通天然砂混凝土,尤其是100%代砂率焚烧灰渣混凝土28 d抗压强度仅为普通天然砂混凝土的一半左右,50%代砂率焚烧灰渣混凝土抗压强度更接近普通天然砂混凝土。     

钢渣微粉在混凝土中的应用研究

本文从钢渣微粉在不同水胶比条件下的活性变化,以及在相同水胶比条件下,与其他混合材的颗粒堆积效应两个方面对钢渣在混凝土中的应用进行了研究,结果表明:钢渣微粉在水胶比高时表现出良好的活性;在水胶比低时,通过与其他混合材的复合使用可实现胶凝材料颗粒的紧密堆积,从而提升混凝土的强度。     

钢渣集料表面改性及其在沥青混凝土中的应用

钢渣用作集料制备沥青混凝土是处理冶炼废弃物和弥补天然集料不足的很好选择,但是钢渣掺量过高会引起沥青混凝土路用性能下降。本研究采用有机硅树脂表面改性技术对钢渣进行处理,研究不同钢渣掺量下沥青混凝土高温、低温及水稳定性变化。通过车辙试验、小梁低温弯曲试验、浸水马歇尔试验和冻融劈裂试验对路用性能进行测试。结果表明,钢渣的掺入对沥青混凝土高温性能有所提高,但钢渣掺量超过60%时开始下降。水稳定性和低温性能随钢渣掺量的增加而下降,但在钢渣集料表面经改性处理后,水稳定性得到显著提高,高温性能也有所改善。根据主要路用性能指标变化情况及规范要求,建议将钢渣掺量控制在60%,对于水稳定要求较高的路面采用有机硅树脂对钢渣进行改性处理。     

Recycled glass replacement as fine aggregate in self-compacting concrete

With increasing environmental pressure to reduce solid waste and to recycle as much as possible, the concrete industry has adopted a number of methods to achieve this goal by replacement of waste glass with concrete composition materials. Due to differences in mixture design, placement and consolidation techniques, the strength and durability of Self Compacting Concrete (SCC) may be different than those of conventional concrete. Therefore, replacement of waste glass with fine aggregate in SCC should deeply be investigated compared to conventional concretes. The aim of the present study is to investigate the effect of glass replacement with fine aggregate on the SCC properties. In present study, fine aggregate has been replaced with waste glass in six different weight ratios ranging from 0% to 50%. Fresh results indicate that the flow-ability characteristics have been increased as the waste glass incorporated to paste volume. Nevertheless, compressive, flexural and splitting strengths of concrete containing waste glass have been shown to decrease when the content of waste glass is increased. The strength reduction of concrete in different glass replacement ratios is not remarkable, thus it can be produced SCC with waste glass as fine aggregate in a standard manner.     

Mechanical and microstructural characterization of an alkali-activated slag/limestone fine aggregate concrete

Four limestone-based, alkali-activated slag fine aggregate concretes, two of which contained amorphous silica in the form of diatomaceous earth, were fabricated using different activating solutions (NaOH/waterglass or Na₂CO₃). Emphasis in this work was placed on using simple manufacturing methods and widely available materials, to ensure that these formulae are practical as construction materials in the developing world. Although cured only at room temperature, these fine aggregate concretes have good compressive strengths (～45 MPa) and their tensile strengths increased from ～2.6 MPa after 1 day of curing to ～4 MPa after 28 day for the NaOH-activated formulae. Samples activated with Na₂CO₃ had negligible tensile strengths after 1 day, increasing to ～2.5 MPa after 28 day. The main cementing phase was shown to be calcium–silicate–hydrates in all formulae; those activated with Na₂CO₃ also showed the presence of hydrotalcite. No evidence of geopolymeric phases was found, though incorporation of Na to form N–S–H that balance charges arising from Al substitution of Si in C–S–H is likely. Despite the short (～120 s) pot life of the strongest formula, NaCl was shown to be an effective retarding agent, which reduced the strengths of different formulae, at worst, by less than 25% after 28 day of curing.     

超高强度高炉矿渣细骨料混凝土的试验研究

通过混凝土配合比设计和力学性能试验,探讨了高炉矿渣代替天然砂作为超高强度混凝土细骨料的可行性,并对比了高炉矿渣代砂混凝土与天然砂混凝土的压缩强度,结果表明:高炉矿渣细骨料混凝土拌合物工作性能优良,压缩强度超过了100 MPa。     

钢渣微粉在粉煤灰加气混凝土中的应用研究

将钢渣微粉应用于加气混凝土中,通过实验研究发现：钢渣微粉较高的比表面积使其需水量偏大,钢渣微粉取代粉煤灰的适宜量为40%,适量钢渣微粉取代粉煤灰可使加气混凝土具有良好的水化产物组成与结构,过量的钢渣微粉取代粉煤灰会导致加气混凝土水化产物C-S-H凝胶数量的大幅度减少。     

Mechanical properties of high-strength concrete incorporating copper slag as coarse aggregate

Copper slag is a by-product obtained during the matte smelting and refining of copper. Current options of management of this slag are recycling, recovering of metal, production of value added products and disposal in slag dumps or stockpiles. This paper presents the results of a study undertaken to investigate the feasibility of using copper slag as coarse aggregates in high-strength concrete. The effects of replacing limestone coarse aggregate by copper slag coarse aggregate on the compressive strength, splitting tensile strength, and rebound hammer values of high-strength concretes are evaluated in this work. Concrete mixtures containing different levels of silica fume were prepared with water to cementitious materials ratios of 0.40, 0.35, and 0.30. The percentages of the cement replacements by silica fume were 0%, 6%, and 10%. The use of copper slag aggregate compared to limestone aggregate resulted in a 28-day compressive strength increase of about 10–15%, and a splitting tensile strength increase of 10–18%. It can be concluded from the results of this study that using copper slag as coarse aggregate in high-strength concrete is technically possible and useful.     

废混凝土作粗集料、废砖作细集料制备再生混凝土的实验研究

将实验室检测用废混凝土试块和废黏土砖经破碎、筛分后,作为再生混凝土粗细集料应用。结果表明,经过合适的配比。配制出满足强度和工作性能要求的混凝土：在严格控制试验用水量的条件下,采用预加水浸泡再生细集料的方法,能够得到工作性能良好的再生混凝土。     

Alternative materials for concrete— Mersey silt as fine aggregate

The possible use of Mersey silt as a fine aggregate for concrete has been investigated. Sound concrete with compressive strength up to 45 N mm^?2 has been made. However, the cement content required for typical mixes is higher than with conventional sands and there is no overall cost saving. Current British Standard limits for silt content of aggregates have been examined critically in the light of available data and it is recommended that the requirement for material finer than 75 μm be eased to 5% of the total aggregate weight.     

用低品位粉煤灰作细骨料研制混凝土小型空心砌块

随着粉煤灰混凝土应用技术的发展,人们进一步认识到只有让粉煤灰三种效应在应用中得到充分发挥,才能控制和保证粉煤灰混凝土及其制品的质量。目前比较成熟的混凝土小型砌块中的粉煤灰用量一般不到10％。本文针对一家电厂大量积压的低品位粉煤灰进行大掺量低品位粉煤灰混凝土小型空心砌块配制研究,以期为工业化生产大掺量粉煤灰混凝土小型砌块提供理论和实验依据。     

Use of fine glass as ASR inhibitor in glass aggregate mortars

Demand for recycled glass has considerably decreased in recent years, particularly for mixed glass. Glass is cheaper to store than to recycle, as conditioners require expenses for the recycling process. In order to provide a sustainable solution to glass storage, a potential and incentive way would be to reuse this type of glass in concretes. Depending on the size of the glass particles used in concrete, two antagonistic behaviours can be observed: alkali–silica reaction, which involves negative effects, and pozzolanic reaction, improving the properties of concrete. The work undertaken here dealt with the use of fine particles of glass and glass aggregates in mortars, either separately or combined. Two parameters based on standardised tests were studied: pozzolanic assessment by mechanical tests on mortar samples and alkali-reactive aggregate characteristics and fines inhibitor evaluations by monitoring of dimensional changes. It is shown that there is no need to use glass in the form of fines since no swelling due to alkali–silica reaction is recorded when the diameter of the glass grains is less than 1 mm. Besides, fine glass powders having specific surface areas ranging from 180 to 540 m²/kg reduce the expansions of mortars subjected to alkali–silica reaction (especially when glass aggregates of diameters larger than 1 mm are used).