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.     

Performance of high wokability slag-cement mortar for ferrocement

The performance of high workability mortar mix, applicable for the casting of thin ferrocement elements by using slag as cement replacement and superplasticizer as water reducing agent is investigated. Cement mortars (1:2. 1:2.5 and 1:3) incorporating various percentages of slag and superplasticizer were designed to have high workability (136±3% flow). Performance of the mortars is studied in terms of compressive strength, unit weight, strength development and water absorption. Effect of three different curing regimes on strength and strength development of the mortars is also the part of this study. The results showed that the high workability slag cement mortars of reasonably high strength, low water absorption and exhibiting early age strength comparable to that of the OPC mortars can be designed in order to cast thin ferrocement elements by the method of pouring.     

The properties of concrete made with fine dune sand

This paper presents the results of a study that investigated the properties of concrete made with dune sand. Different control concrete mixtures using ordinary Portland cement (OPC) with a minimum design compressive strength of 40 N/mm² were prepared. The amount of fine aggregates constituted about 36% by weight of all the aggregates. The workability ranged from low of 16 mm to a high of 122 mm. For each control mix, other mixtures were prepared in which the fine aggregates were replaced by different percentages of dune sand ranging from 10% to 100%. The effect of dune sand on the workability, compressive strength, tensile strength, modulus of elasticity and initial surface absorption test (ISAT) was studied. Experimental results show an improvement in the workability of concrete when fine aggregates were partially replaced by dune sand. An increase in slump was measured with increase in dune sand content. However, at high dune sand contents (above 50%); the slump starts to decrease with an increase in dune sand. Generally, the strength values decrease with increase in dune sand replacement. The strength loss was not found considerable as the maximum reduction was less than 25% when fine aggregates were fully replaced by dune sand. The absorption characteristics of concrete made with OPC as measured by the (ISAT) generally increased with higher dune sand contents.     

利用海砂制备高性能混凝土试验研究

研究了细集料砂对水泥胶砂性能的影响,并以海砂为细骨料制备高性能混凝土,分别进行了C60、C100等级海砂高性能混凝土工作性能、力学性能以及耐久性能试验研究。结果表明:海砂水泥胶砂抗压强度比河砂低,但是抗折强度要高于河砂;海砂制备同等级高性能混凝土的工作性、28 d抗压强度及劈裂抗拉强度要优于天然河砂,且早期强度发展迅速;采用电通量法和NEL法评价的氯离子渗透性都处于很低的水平,为海砂混凝土的研究与应用提供了研究基础,为制定海砂混凝土应用技术规范提供重要参考。     

矿渣代砂水泥砂浆及混凝土物理力学性能研究

研究了高炉矿渣作为细骨料的本征特性及其不同代砂率水泥砂浆及混凝土的物理力学性能.结果表明:矿渣与天然砂作为细骨科时,其物理化学性能存在一定差异;与基准水泥砂浆相比,矿渣代砂水泥砂浆的需水性增大,早期抗折强度略有降低,但后期抗折强度不但不降低甚至还略有提高,抗压强度略有降低,干缩性减小;相对于普通混凝土,矿渣代砂混凝土的抗折强度和抗压强度均有所提高.     

Using burnt stone slurry in mortar mixes

The accumulation of stone slurry waste resulting from quarries forms a serious environmental problem in many countries around the globe. The use of Jordanian burnt stone slurry (BSS) waste in concrete mixtures had been investigated throughout this study. The properties that were studied include setting time, workability, compressive and flexural strength, alkali-silica reaction, and micro-structure of mortar. The BSS was used as a partial replacement of cement and sand with different replacement percentages including 0%, 5%, 10% and 15%. Mortar mixes have a mix proportion of 1:3:0.7 by weight for cement, sand and water, respectively.Test results showed that BSS waste can be used in concrete mixtures to reduce the environmental pollution resulting from the accumulations of BSS waste. The setting time and workability decreased with the increase of BSS content. On the other hand, the compressive and flexural strength of mortar increased with the increase of BSS content under both moist and autoclaving curing. The autoclaved BSS concrete showed higher durability to alkali-silica reaction damage compared to the moist cured BSS concrete. Scanning electron microscopy images showed that BSS mortar is denser and have more homogeneous micro-structure compared to plain mortar.     

全再生混凝土概念的衍化与研究进展

全面梳理和分析了再生混凝土的发展历程与演变特点,提出了全再生混凝土的基本概念,基于文献分析,针对不同组分、不同取代率下再生混凝土的工作性能、力学性能和耐久性能开展了对比分析.整理了当再生粗骨料、再生细骨料分别单取代且取代率达到100％ 及再生粗、细骨料双取代的取代率都达到100％ 后混凝土各性能变化的量值,最后总结了再...     

矿粉在混凝土中的运用

通过试验讨论了矿渣微粉对混凝土工作性能、抗压强度及耐久性的影响。结果表明，掺矿渣微粉，特别是复掺矿粉和粉煤灰可改善混凝土的性能。     

矿渣微粉在高性能混凝土中的应用

讨论了矿渣微粉对高性能混凝土工作性能、抗压强度及耐久性的影响。结果表明,掺矿渣微粉可改善混凝土的性能,具有良好的综合效益。     

Durability of blast-furnace slag mortars subjected to sodium monofluorophosphate application

The aim of this study is to investigate the effect of sodium monofluorophosphate (Na-MFP) on frost scaling durability and transport properties of carbonated blast-furnace slag cement (BFSC) mortar. The application of Na-MFP solution as curing solution and also surface treatment compound for BFSC mortar was evaluated. Three different Na-MFP solutions with concentrations of 10%, 20% and 30% by weight. in water were used as curing solution and surface treatment compound. The experimental results reveal that both techniques significantly improve the frost salt scaling durability and microstructure of carbonated blast-furnace slag mortar. Moreover, the carbonation rate and capillary water uptake of the treated mortars were substantially decreased compared with the untreated specimen. The mortars cured in Na-MFP solution show higher compressive strength than the untreated control after carbonation exposure. In general, the durability performances were improved when increasing the concentration of the Na-MFP solution applied.     

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。     

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。     

Effects of portland composite and composite cements on durability of mortar and permeability of concrete

In this study, the effects of Portland composite and composite cement on the properties of cement paste, durability of mortar and permeability of concrete were investigated. The results were compared with reference mixture of cement paste, mortar and concrete made with Portland cement. The ratio of water to cementitious materials (W/C_m) in cement paste, mortar and concrete mixtures were determined in a way that all the similar mixtures had the same workability. Flexural tensile and compressive strength of mortar samples containing Portland Composite and Composite cement were determined at various ages. In cement paste samples, the shortest and longest setting time was obtained in samples made with Portland and composite cement, respectively. Also, maximum amount of volume expansion was found in the sample made with Portland composite cement. Mortar samples made with Portland composite and composite cement had lower strength values than the reference mortar mixture at early ages but at 28 days and later ages they had higher strength values than the reference mixture. In durability tests, there was no loss of weight and cracks in mortar mixture samples made with Portland composite and composite cement when they were held in microthiol, Na₂SO₄ and MgSO₄ solutions. Also, no water leakage was observed through the concrete samples made with Portland composite and composite cement when they were held under five-bar pressurized water.     

Effect of fineness of ash on pozzolanic properties and acid resistance of sugarcane bagasse ash replaced cement mortars

This paper addresses the potential use of Sugar Cane Bagasse Ash (SCBA) as a pozzolanic material for partial cement replacement in concrete mixtures. Cement mortars containing SCBA having five different particle size distributions at a replacement rate of 20% by weight were used to study the chemical and physical pozzolanic properties of SCBA. The durability of SCBA replaced mortars was also evaluated. SCBA with 0% retained on sieve No. 325 was used to replace 20% by weight of cement and create mortar specimens that were subjected to sulfuric acid attack of varying concentrations (1%−3% by weight of water). The tested samples were observed to check visual distortion, mass loss, and compressive strength loss at 1, 7, 14, 28, and 56 d of acidic exposure, and the results were compared to those for the control sample, that was lime water cured, at the same ages. The SCBA sets were found to meet the requirements for pozzolan class N specified by ASTM C 618. Mortars containing SCBA with 0% or 15% retention produced better compressive strength than the control mortars after 28 d. Additionally, X-ray fluorescence and X-ray diffraction analysis showed that the SCBA had favorable chemical properties for a pozzolanic material. Furthermore, SCBA replaced samples at all ages showed improved resistance against acidic attack relative to that of the control mortars. Maximum deterioration was seen for 3% concentrated solution. This study’s findings demonstrated that SCBA with an appropriate fineness could be used as a pozzolanic material, consistently with ASTM C 618.     

利用磨细钢渣矿粉配制C60高性能混凝土的研究

本文将经过闷渣和超细粉磨处理的钢渣矿粉用于配制C60强度等级高性能混凝土,研究了掺磨细钢渣矿粉混凝土的新拌工作性能、抗压强度、收缩性能以及抗氧离子渗透、抗冻性、抗钢筋锈蚀等耐久性能。研究结果表明,适量磨细钢渣掺入混凝土中可以提高混凝土的工作性能、抗压强度以及耐久性能;将磨细钢渣与优质粉煤灰复掺可以发挥超叠加效应,进一步改善混凝土性能;另外,掺入磨细钢渣矿粉可以降低混凝土的早期收缩。     

Mechanical properties of copper slag reinforced concrete under dynamic compression

The dynamic mechanical properties of copper slag reinforced concrete (CSRC) were studied using a 50-mm-diameter split Hopkinson pressure bar (SHPB) system. The microstructures of control concrete and CSRC with various contents of copper slag as replacement of sand were investigated by Scanning Electron Microscope (SEM). The dynamic compressive strength of CSRC was generally improved with substitutional amounts of copper slag up to 20%, compared with the control concrete, beyond which the strength reduced. With the increasing content of copper slag as replacement of sand, there appeared to be higher content of voids, microcracks and capillary channels in CSRC than that in control concrete, which was mainly attributed to the presence of excess water and it resulted in deterioration of concrete quality.     

Effect of Granulated Blast Furnace Slag and fly ash addition on the strength properties of lightweight mortars containing waste PET aggregates

In this work, the effect of Granulated Blast Furnace Slag (GBFS) and fly ash (FA) addition on the strength properties of lightweight mortars containing waste Poly-ethylene Terephthalate (PET) bottle aggregates was investigated. Investigation was carried out on three groups of mortar specimens. One made with only Normal Portland cement (NPC) as binder, second made with NPC and GBFS together and, third made with NPC and FA together. The industrial wastes mentioned above were used as the replacement of cement on mass basis at the replacement ratio of 50%. The size of shredded PET granules used as aggregate for the preparation of mortar mixtures were between 0 and 4 mm. The waste lightweight PET aggregate (WPLA)–binder ratio (WPLA/b) was 0.60; the water–binder (w/b) ratios were determined as 0.45 and 0.50. The dry unit weight, compressive and flexural–tensile strengths, carbonation depths and drying shrinkage values were measured and presented. The results have shown that modifying GBFS had positive effects on the compressive strength and drying shrinkage values (after 90 days) of the WPLA mortars. However, FA substitution decreased compressive and flexural–tensile strengths and increased carbonation depths. Nevertheless a visible reduction occurred on the drying shrinkage values of FA modifying specimens more than cement specimens and GBFS modified specimens. The test results indicated that, GBFS has a potential of using as the replacement of cement on the WPLA mortars by taking into consideration the characteristics. But using FA as a binder at the replacement ratio of 50% did not improve the overall strength properties. Although it was thought that, using FA as binder at the replacement ratio of 50% for the aim of production WPLA concrete which has a specific strength, would provide advantages of economical and ecological aspects.     

磨细钢渣粉对水泥混凝土性能影响的研究

研究了磨细钢渣粉的掺量对水泥胶砂和水泥混凝土工作性与强度的影响,以及钢渣粉和粉煤灰不同比例复掺对混凝土性能的影响.结果表明,磨细钢渣粉在一定程度上可以改善混凝土的工作性,降低混凝土的强度,钢渣粉掺量不宜大于30％;钢渣粉与粉煤灰复掺可以发挥超复合效应,配制出C40以上的高性能混凝土.     

Effect of copper slag and cement by-pass dust addition on mechanical properties of concrete

This research was undertaken to study the effect of copper slag (CS) and cement by-pass dust (CBPD) addition on concrete properties. In addition to the control mixture, two different trial mixtures were prepared using different proportions of CS and CBPD. CBPD was primarily used as an activator. One mixture consisted of 5% copper slag substitution for portland cement. The other mixture consisted of 13.5% CS, 1.5% CBPD and 85% portland cement. Three water-to-binder (w/b) ratios were studied: 0.5, 0.6 and 0.7. Concrete cubes, cylinders and prisms were prepared and tested for strength after 7 and 28 days of curing. The modulus of elasticity of these mixtures was also evaluated. Results showed that 5% copper slag substitution for portland cement gave a similar strength performance as the control mixture, especially at low w/b ratios (0.5 and 0.6). Higher copper slag (13.5%) replacement yielded lower strength values. Results also demonstrated that the use of CS and CBPD as partial replacements of portland cement has no significant effect on the modulus of elasticity of concrete, especially at small quantities substitution.     

牡蛎壳替代部分细骨料对混凝土基本性能影响机理的研究

为研究牡蛎壳替代部分细骨料混凝土强度降低的影响机理,设计了细骨料替代率分别为0、20%、40%、60%的混凝土。标准养护在规定龄期进行和易性、吸湿性,强度、TGA和SEM试验。结果表明:牡蛎壳混凝土抗压强度发展规律与普通混凝土一致。含有牡蛎壳的混凝土水化硬化后CaCO3的含量随牡蛎壳的增加而增多,混凝土内部结构也越松散。牡蛎壳混凝土比普通混凝土的吸湿性好,可以利用牡蛎壳混凝土调节环境干湿度。