菱镁矿粉对混凝土性能影响的试验研究

在C30混凝土基准配合比的基础上,掺入占水泥质量1%~6%的菱镁矿粉,主要研究菱镁矿粉掺量对混凝土体积稳定性、耐久性和抗压强度的影响。结果表明,掺入菱镁矿粉后混凝土的各项性能均有不同程度的提高,其适宜掺量为占水泥质量的4%~5%,为提高混凝土体积稳定性和耐久性提供了一种新的技术措施。     

陶瓷抛光砖粉在水泥和混凝土行业中的应用研究

对陶瓷抛光砖粉作为水泥混合材和混凝土矿物掺合料进行研究。研究结果表明：在一定掺量的情况下，陶瓷抛光砖粉作为水泥混合材和混凝土矿物掺合料是可行的。     

矿渣粉颗粒级配、掺量的优化研究

研究掺入超细矿渣粉,改善水泥颗粒级配对水泥胶砂及混凝土的工作性、强度和耐久性的影响结果表明:矿渣粉细度大于P600,掺量不高于30%,可提高砂浆和混凝土的强度;适当提高矿渣粉的细度和掺量,可以改善混凝土抗氯离子指标;综合考虑工作性、强度、耐久性和经济性,配制高强及高性能混凝土适宜掺加10%～20%的P800型矿渣粉.     

煤渣粉对高性能混凝土性能的影响

用煤渣粉作为矿物掺合料制备 C50高性能混凝土,并与Ⅱ级粉煤灰复掺,研究煤渣粉掺量对水泥凝结时间、混凝土流动性、抗压强度及耐久性的影响.结果表明:煤渣粉替代部分水泥可以提高高性能混凝土的抗压强度和抗氯离子渗透性,对混凝土性能的影响优于Ⅱ级粉煤灰;煤渣粉掺量为20%时,混凝士抗压强度达到最大值,为空白样的120%;煤渣粉...     

陶瓷粉对中低标号混凝土工作性及强度影响

以陶瓷抛光砖在研磨抛光过程中收集的陶瓷微粉作为一种新型混凝土矿物掺合料,研究了同等掺量下陶瓷粉和粉煤灰的混凝土工作性能与3~90d的抗压强度增长规律。试验表明:掺陶瓷粉的混凝土表现出优良的粘聚性,混凝土3~28d抗压强度增长幅度与同等掺量下粉煤灰混凝土基本一致;对于C20和C25混凝土,28~90d强度增长粉煤灰比陶瓷粉略高;对于C30和C35混凝土,28~90d强度增长粉煤灰与陶瓷粉基本一致。结合陶瓷粉和粉煤灰的特点,对双掺陶瓷粉-粉煤灰的C30混凝土配合比进行优化设计,当陶瓷粉与粉煤灰比例为1:3时,混凝土工作性最佳,28d强度达到35.7MPa,28~90d增幅达到27%。     

陶瓷抛光砖粉对混凝土性能的影响

研究利用陶瓷抛光砖粉作混凝土掺合料,并将之与粉煤灰对比,测试了抛光砖粉对混凝土强度、工作性、抗氯离子渗透以及抗硫酸盐侵蚀性能的影响,并采用SEM以及EDS等测试方法研究其水化产物及微观形貌.结果表明:抛光砖粉可增强混凝土抗氯离子渗透能力及抗硫酸盐侵蚀能力,提高混凝土的黏聚性和保水性,但会使流动性变差.与掺等量粉煤灰混凝土相比,掺抛光砖粉混凝土强度较高,且早期强度表现尤为明显.复掺抛光砖粉与粉煤灰,混凝土综合性能较好.     

陶瓷抛光砖粉作为混凝土掺合料的研究

本文研究了抛光砖粉用作混凝土掺合料的可行性。研究结果表明:(1)掺30%抛光砖粉的水泥胶砂28d抗压强度比为81%,具有较高的火山灰活性指数。(2)在相同配比条件下,单掺抛光砖粉的混凝土28d强度高于掺实验用粉煤灰的混凝土。(3)抛光砖粉用作混凝土掺合料时,与粉煤灰复掺比单掺更为有利。在掺合料用量相同时,复掺抛光砖粉与实验用粉煤灰的混凝土28d强度高于单掺抛光砖粉或实验用粉煤灰的混凝土。     

预拌混凝土中陶瓷抛光砖微粉替代粉煤灰的配合比实验研究

随着建筑行业的快速发展,混凝土的需求量越来越大。由于受粉煤灰的资源缺乏限制,阻碍了混凝土行业的发展。本文研究了以陶瓷抛光砖微粉取代部分矿物掺合料(粉煤灰),对比相应配比混凝土的性能,外加剂掺量变化,抗压强度等指标。分析陶瓷抛光砖微粉取代部分粉煤灰应用于实际的混凝土中的可行性。结果表明:一定掺量下的陶瓷抛光砖微粉,对于提高混凝土耐久性和抗压强度具有显著作用。且由于陶瓷抛光砖微粉价格低,能够降低混凝土的单方成本,这有利于混凝土企业的降本增效。     

钢渣-低品位粉煤灰复掺对水泥胶砂及混凝土长期性能的影响

研究了热焖钢渣与低品位粉煤灰复掺作为矿物掺合料对水泥胶砂工作性能和强度的影响以及对混凝土的长期强度发展和耐久性的影响。结果表明,热焖钢渣与低品位粉煤灰按比例1:1复掺能够有效提高水泥胶砂的工作性能和强度。混凝土中掺加复合矿物掺合料,掺量在30%以内,混凝土工作性能明显改善,强度发展理想;掺量20%时,混凝土耐久性便得到明显提高,干燥收缩、抗碳化和抗Cl-渗透能力显著优于空白组,干燥收缩优于掺同比例矿渣的混凝土。     

钢渣粉硅灰混凝土的力学性能及耐久性研究

通过试验测试分析了钢渣粉单掺以及与硅灰二元复掺混凝土在不同配合比下的和易性、力学性能和耐久性能,并基于改性前后混凝土微观结构特征的测试分析揭示了钢渣粉单掺以及与硅灰二元复掺对混凝土材料的改性机理。试验研究结果表明:钢渣粉取代混凝土中水泥最适宜的比例是10%,此时混凝土的力学性能和耐久性能都得到有效的提高,掺量20%的钢渣混凝土与普通硅酸盐混凝土各项性能相近。钢渣粉与硅灰的二元复掺可以使混凝土的力学性能和耐久性得到显著提高。钢渣粉在混凝土中的作用有两个:一是作为活性胶凝材料发生水化反应,但其活性比水泥低;二是微集料效应,分散水泥颗粒填充混凝土的孔隙,提高混凝土的密实度。     

C45铁铝酸盐水泥混凝土制备与性能研究

针对铁铝酸盐水泥快硬、低收缩与高耐蚀特性,结合结构工程对铁铝酸盐水泥混凝土的需求,采用缓凝型聚羧酸减水剂制备C45铁铝酸盐水泥混凝土,并探索其力学性能与耐久性能。结果表明,C45铁铝酸盐水泥混凝土拌合物性能良好,出机坍落度215mm,90min损失仅为10mm,凝结时间可保证施工。28d抗压强度达到C50强度等级,84d电通量低至169C,28d开裂指数35%,耐久性能优于普通硅酸盐水泥混凝土。     

High performance concrete containing lower slag amount: A complex view of mechanical and durability properties

A wide set of parameters of concrete containing 10% of ground granulated blast furnace slag as Portland cement replacement involving basic material characteristics, mechanical and fracture-mechanical properties, durability characteristics, hydric and thermal properties and chloride binding characteristics is determined and compared with the parameters of reference Portland cement concrete with otherwise the same composition. The experimental results show that the replacement of Portland cement by even such a low amount of ground granulated blast furnace slag as environmental more friendly and still valuable alternative binder either affects positively or at least does not worsen in a significant way the substantial properties of hardened concrete mix. The mechanical and fracture-mechanical properties are found to be very similar as compared to the reference mix, the liquid water transport parameters of the mix containing slag are significantly better, the basic durability characteristics such as the frost resistance and corrosion resistance similar and very good, the resistance against de-icing salts slightly worse. These findings may be significant for the future use of slag in the countries where its available amount is decreasing and its more efficient use as a binder than it was common to date can appear necessary.     

High performance concrete with Czech metakaolin: Experimental analysis of strength,toughness and durability characteristics

Although the capability of metakaolin as pozzolanic material to improve mechanical and durability properties of concrete if used as partial replacement of Portland cement is well noted in concrete science, its utilization in building industry was limited to date, mainly due to its high price dictated by the low production amounts. However, with the current shortage of silica fume and high-quality slag in some countries the attitude of concrete producers to metakaolin may change in the near future. This change of mind can be facilitated by providing a more comprehensive view of the properties of composite materials with metakaolin, thus contributing to wider realization of the benefits of metakaolin in concrete. In this paper, an extensive set of parameters of high performance concrete (HPC) with metakaolin including basic physical characteristics, mechanical and fracture-mechanical properties, durability characteristics, hydric and thermal properties and chloride binding characteristics is measured. The experimental results show that the replacement of Portland cement by 10% of metakaolin as an optimal amount leads in most cases either to improvements or at least does not significantly impair substantial properties of the analyzed HPC. Basic physical properties and heat transport and storage properties are very similar to common HPC, mechanical and fracture-mechanical properties after 28 days are slightly worse but later improved, water- and water vapor transport parameters are substantially reduced, frost resistance is better, resistance against de-icing salts is slightly worse but still meets very well the required criteria. The chemical resistance of concrete with 10% of metakaolin instead of Portland cement in distilled water and HCl is found better than for Portland cement concrete, in MgCl₂ it is slightly worse, and in NH₄Cl, Na₂SO₄ and CO₂ almost the same, carbonation is reduced, and chloride binding capacity is increased.     

粉煤灰和抛光渣抑制碱硅酸反应及其机理研究

采用砂浆棒快速法,分别以0%、20%、30%、40%的粉煤灰和抛光渣等质量取代水泥制备砂浆试件,进行膨胀率及强度测试,借助扫描电镜(SEM)、能谱分析(EDS)和X射线衍射(XRD)等方法对碱环境下集料与胶凝材料界面过渡区的微观结构、元素组成和生成物进行分析,研究粉煤灰和抛光渣抑制碱硅酸反应(ASR)的内在机理.结果表明:粉煤灰和抛光渣均可有效抑制ASR,综合考虑粉煤灰、抛光渣对ASR的抑制作用和对材料强度的影响,粉煤灰、抛光渣取代率宜取20%～30%;掺粉煤灰和抛光渣均可使界面过渡区结构更致密;界面过渡区钙硅比和钠硅比明显降低;钾硅比和铝硅比在界面过渡区有突变,K和Al在界面过渡区富集,原因为K~+比Na~+更倾向于与Al_2O_3结合.尽管抛光渣碱含量较高,但其中高含量的SiO_2、Al_2O_3及活性集料中的SiO_2可与体系中的Na~+、K~+共同作用,在界面过渡区生成体积稳定的架状结构硅酸盐矿物钾霞石KAlSiO_4和霞石(K,Na)AlSiO_4,从而抑制ASR.     

阿利特-硫铝酸钡钙水泥混凝土的试配及力学性能的研究

根据混凝土的配合比设计及试验室现场操作,配制出工作性良好的阿利特-硫铝酸钡钙水泥混凝土.采用对比试验研究的方法,研究了不同水灰比对该水泥混凝土抗压强度的影响,并将其与相同配合比的普通混凝土的力学性能进行比较.试验结果表明:两种混凝土的抗压强度均随水灰比的增大而减小;相同配合比下,该水泥混凝土的抗压强度比同龄期的普通混凝土有了明显的改善,尤其早期抗压强度,1d强度提高了50%～65%.微观结构分析发现:阿利特-硫铝酸钡钙水泥混凝土中水化产物的粒径分布均匀,界面粘结状况较好,结构较为致密.     

Effects of the usage of diatomite and waste marble powder as partial replacement of cement on the mechanical properties of concrete

Diatomite is a pozzolanic material containing amorphous silica, cristabolite and minor amounts of residual minerals. Waste marble powder (WMP) is an inert material which is obtained as an industrial by product during sawing, shaping, and polishing of marble and causes a serious environmental problem. This paper describes the procedures and results of a laboratory investigation of mechanical properties carried out on the concrete specimens containing diatomite and WMP as partial replacement of cement in concrete. The laboratory work essentially consists of characterization of the raw and waste materials, preparation of concrete specimens with diatomite and WPM in different ratios by weight as replacement for cement and a superplasticizing admixture to reduce water demand and compression and flexural tests of the specimens. Test results indicated that the concrete specimens containing 10% diatomite, 5% WPM and 5% WPM +10% diatomite replacement by weight for cement had the best compressive and flexural strength and the replacement of cement with diatomite and WMP separately and together using a superplasticizing admixture could be utilized to improve the mechanical properties of the conventional concrete mixtures.     

Effect of electric arc furnace dust on the properties of OPC and blended cement concretes

This paper presents results of a study conducted to evaluate the mechanical properties and durability characteristics of ordinary Portland cement (OPC) and blended cement (silica fume and fly ash) concrete specimens prepared with electric arc furnace dust (EAFD). Concrete specimens were prepared with and without EAFD. In the silica fume cement concrete, silica fume constituted 8% of the total cementitious material while fly ash cement concrete contained 30% fly ash. EAFD was added as 2% replacement of cement in the OPC concrete and 2% replacement of the total cementitious content in the blended cement concretes. Mechanical properties, such as compressive strength, drying shrinkage, initial and final setting time, and slump retention were determined. The durability characteristics were evaluated by measuring water absorption, chloride permeability, and reinforcement corrosion. The initial and final setting time and slump retention increased due to the incorporation of EAFD in both OPC and blended cement concretes. The drying shrinkage of EAFD cement concrete specimens was more than that of concrete specimens without EAFD. The incorporation of EAFD was beneficial to OPC concrete in terms of strength gain while such a gain was not noted in the blended cement concretes. However, the strength differential between the blended cement concretes with EAFD and the corresponding concretes without EAFD was not that significant. The water absorption and chloride permeability, however, decreased due to the incorporation of EAFD in both the OPC and blended cement concretes. The corrosion resistance of OPC and blended cement concrete specimens increased due to the addition of EAFD.     

珍珠岩掺合料混凝土轨枕制备研究

通过试验测试研究珍珠岩矿物掺合料及其对混凝土主要性能的影响，在混凝土中珍珠岩掺合料替代水泥10％～20％可不同程度地改善工作性能，提高后期强度。该掺合料替代水泥20％制备C60混凝土铁道Ⅲ型轨枕的试验及其检测结果显示其主要性能指标均有所提高。     

阿利特-硫铝酸钡钙水泥混凝土的试配及力学性能的研究

根据混凝土的配合比设计及试验室现场操作,配制出工作性良好的阿利特-硫铝酸钡钙水泥混凝土。采用对比试验研究的方法,研究了不同水灰比对该水泥混凝土抗压强度的影响,并将其与相同配合比的普通混凝土的力学性能进行比较。试验结果表明:两种混凝土的抗压强度均随水灰比的增大而减小;相同配比下,该水泥混凝土的抗压强度比同龄期的普通混凝土有了明显的改善,尤其早期抗压强度,1 d强度提高了50%~65%。微观结构分析发现:阿利特-硫铝酸钡钙水泥混凝土中水化产物的粒径分布均匀,界面粘结状况较好,结构较为致密。     

粉煤灰掺量对高性能混凝土强度和耐久性的影响

本文着重研究了粉煤灰掺量对于高性能混凝土强度、氯离子渗透性的影响。水胶比为0．28,粉煤灰掺量在40％以内,可以配制出早期、后期强度均高于不掺粉煤灰、而水泥用量高达600kg/m^3的纯硅酸盐水泥混凝土的相应强度,这种配合比的混凝土28d强度在80MPa以上;并且流动性好,可以满足泵送需要;抗渗性好,属于渗透性“很低”的等级;对于高性能混凝土强度而言,有一个较优的粉煤灰掺量,约为20％－30％;早期强度对应的粉煤灰较优掺量约为10％左右。