The role of industrial by-products in self-compacting concrete

The development of self-compacting concrete is considered as a milestone achievement in concrete technology due to several advantages. In order to be self-compactable the fresh concrete must show high fluidity besides good cohesiveness. For the purpose of evaluating these properties, several concrete mixtures were prepared with a water to cement ratio of 0.45 in the presence of an acrylic-based superplasticizer at a dosage ranging from 1% to 2% by weight of very fine material fraction (maximum 150 μm). Either limestone powder or fly ash or recycled aggregate powder (that is a powder obtained from the rubble recycling process) were used as mineral addition, in order to assure adequate rheological properties, in terms of cohesiveness, in the self-compacting concretes. Preliminary rheological tests were carried out on cement pastes containing these mineral additions. In some cases, recycled instead of natural aggregate was used by substituting either the coarse or the fine aggregate fraction. The fresh concrete properties were evaluated through slump flow, L-box test and segregation resistance. Compressive strength of concrete was determined at 1, 3, 7 and 28 days of wet curing. Results obtained showed that an optimization of self-compacting concrete mixture seems to be achievable by the simultaneous use of rubble powder and coarse recycled aggregate with improved fresh concrete performance and unchanged concrete mechanical strength.     

Properties of concrete using metallurgical industrial by-products as aggregates

The use of industrial by-products and waste materials in concrete opens a whole new range of possibilities in the reuse of materials in the building industry. In this research study, concretes were made with chemical foundry sand (QFS) and green foundry sand (GFS) as substitution for raw sand. Also Electric arc furnace slag (EAFS) and blast furnace slag (BSF) were used as substitution for coarse raw aggregates in 25%, 50% and 100% of concrete production. Two concrete production stages were carried out. In stages 1 and 2, slump test and compressive and tensile splitting strengths and modulus of elasticity were determined. Due to adequate properties of all concretes found in stage 2, length change (during 56 weeks), sorptivity and high temperature exposure evaluation were also determined. The tests results obtained from concretes produced in stages 1 and 2 were compared with those of conventional concrete (CC) and the adequate use of the by-products for concrete production was verified.     

Production of high-strength concrete using high volume of industrial by-products

The production of a high-strength, high performance concrete using high volumes of industrial by-products is tested in laboratory mixtures. The by-products used are high-calcium fly ash and ladle furnace slag as binders and electric arc furnace slag as aggregates. Fly ash is used as 50% by mass of the total binder and ladle furnace slag as 30% by mass of the total binder. Slag aggregates are used in replacement of coarse aggregate or in replacement of both fine and coarse aggregates. In the mixtures containing both supplementary cementitious materials and slag aggregates the produced concrete shows high-strength (>70 MPa), good abrasion resistance and fracture toughness.     

Production of high strength concrete by use of industrial by-products

Blast furnace slag aggregates (BFSA) were used to produce high-strength concretes (HSC). These concretes were made with total cementitious material content of 460–610 kg/m³. Different water/cement ratios (0.30, 0.35, 0.40, 0.45 and 0.50) were used to carry out 7- and 28-day compressive strength and other properties. Silica fume and a superplasticizer were used to improve BFSA concretes. Slump was kept constant throughout this study. Ten percent silica fume was added as a replacement for ordinary portland cement (OPC) in order to obtain HSC. The silica fume was used as highly effective micro-filler and pozzolanic admixture. Superplasticizer at dosages of 2%, 1.5%, 1%, 0.5% and 0% by OPC weight for 0.30, 0.35, 0.40, 0.45 and 0.50 w/c ratios, respectively, were adopted. Results showed that compressive strength of BFSA concretes were approximately 60–80% higher than traditional (control) concretes for different w/c ratios. These concretes also had low absorption and high splitting tensile strength values. It is concluded that BFSA, in combination with other supplementary cementitious materials, can be utilized in making high strength concretes.     

工业废渣开发生产轻集料混凝土砌块

利用工业废渣开发生产各种轻集料混凝土砌块,做到了变废为宝,化害为利,具有显著的经济效益和社会效益,值得推广应用。     

粉煤灰砌块在发电厂生产主厂房的应用

秦皇岛发电有限责任公司装机容量 10 0万千瓦 ,生产主厂房及电控楼为混凝土框架结构。一期(2 0万千瓦× 2 )生产主厂房墙体投产后大面积出现裂纹、龟裂现象。在二期 (30万千瓦× 2 )生产主厂房扩建中 ,为了避免墙体出现裂纹等现象和推动工业建筑墙体材料改革 ,经调研论证后进行了粉煤灰空心砌块的研制 ,并应用在为扩建生产主厂房及电控楼墙体封闭。自 1994年 6月封闭至今已七年 ,墙体状况良好 ,墙体表面未出现裂纹、龟裂、空鼓等现象 ,满足了火力发电厂生产的需要。1　粉煤灰空心砌块的研制1 1　粉煤灰空心砌块配方试验按照华北电力设计院土…     

Production of MgO-type expansive agent in dam concrete by use of industrial by-products

A novel MgO-type expansive agent in a designed formula has been prepared with industrial by-products—magnesite, serpentine and dolomite calcined at 1150 °C for 1 h. The compositions of expansive agent were studied by X-ray diffractometry (XRD), DSC and scanning electron microscopy (SEM), and the results showed that the main phases were MgO, CaO and C₂S. The hydration of CaO to Ca(OH)₂ is quick and can be completed in 3 days in water at 20 °C, and MgO to Mg(OH)₂ is slow and about 57% MgO hydrates into Mg(OH)₂ in 180 days under the same condition, which is quicker than in water. The hydrations of CaO and MgO generate expansions in early and later age, respectively.     

利用工业废渣生产水泥的探讨

介绍了钢渣水泥研制成功的意义,详细阐述了具体的试验材料配比、试验结果及方案的确定过程,指出实验的研制成功,对提高企业的经济效益,使企业走可持续发展道路具有一定的意义。     

Effect of blended cements produced with natural zeolite and industrial by-products on alkali-silica reaction and sulfate resistance of concrete

In this study, influence of blended cements produced with different types of pozzolans on alkali-silica reaction (ASR) and sulfate resistance of concrete was investigated. For this reason, natural zeolite (clinoptilolite), fly ash (FA), and ground granulated blast furnace slag (GBFS) were used in different types of blended cement production. According to the mechanical performance of these blended cements, ASR and sulfate resistance experiments were carried out to obtain the durability performance of these cements. The length changes and microstructure investigations of the mortar specimens with different types of blended cements showed that zeolite, FA, and GBFS had reduced ASR and sulfate damages when compared with ordinary CEM I 42.5 reference specimen.     

Evaluation of controlled low strength materials containing industrial by-products

A controlled low strength material (CLSM) is a self-compacted, cementitious material used primarily as a backfill. It is also known as a flowable fill which is usually a mixture of fine aggregates, small amount of cement, fly ash, and water. To be classified as a CLSM, the mixture must have a compressive strength between 345 and 8400 kPa. This paper evaluates the potential use of cement by-pass dust, incinerator ash and copper slag as a CLSM. Mixtures were designed to produce a CLSM, with a low compressive strength (less than 1034 kPa), that can be excavated without using any mechanical equipment. Slump, unit weight and unconfined compressive strength tests were conducted on various mixtures. Cubical and cylindrical specimens were prepared and cured at room temperature and in sealed plastic bags. Results indicate that with a good mix design it is possible to produce a CLSM with good mechanical properties to meet design requirements. Mixing these materials with cement and sand produced better results than using them alone due to their low pozzolanic activity. Curing method and period can have considerable effects on the strength of a CLSM.     

论清水混凝土施工技术

论述了清水混凝土的工艺质量标准、基本要求、模板工程、混凝土工程、混凝土成本整修等内容。指出应用该技术既可节约抹灰材料，加快施工进度，降低工程造价，又可保证工程的质量，最后对今后的广泛应用进行了展望。     

谈清水混凝土的应用

就清水混凝土优势以及特点进行了分析,并阐述了阻碍清水混凝土在国内发展的因素,同时针对清水混凝土在施工方面所出现的缺陷进行了讨论,提出具体的解决方法。     

框架结构清水混凝土施工

结合工程实例，介绍了框架结构清水混凝土的技术，从工程概况、清水混凝土总体要求、施工工艺等方面进行了论述，指出框架结构清水混凝土施工，不仅可免去抹灰，而且可降低成本，提高工程质量。     

废弃泡沫混凝土制备再生泡沫板材的研究

随着建筑的拆迁与重建,废弃泡沫混凝土将大量产生。针对这一点,提出了废料高效再生利用的技术路线和方法。将粉碎后的废料经过煅烧粉磨,制备得到可再次水化的再生胶凝材料。在矿渣碱激发的体系下用此再生材料制备泡沫混凝土。试验结果表明,煅烧温度设置在650℃附近时可得到优秀的再生胶凝材料,可完全替代水泥组分制备泡沫混凝土,成品密度为600 kg/m~3,28d抗压强度为4.3MPa,导热系数为0.155 W/(m·K),收缩为0.48 mm/m,冻融质量损失为2.8%,冻融强度损失为4.5%。     

利用电石灰等工业废渣生产小型空心砌块

介绍利用电石灰、粉煤灰、炉渣等工业废渣,配以水泥、浮石等原料,生产小型空心砌块的原料配比、生产工艺及主要设备。以年产4万m3小型空心砌块计,可利用电石灰1万多t,其它工业废渣2万多t。     

再生骨料混凝土空心砌块的试验研究

利用再生骨料生产混凝土空心砌块对于建筑节能和墙体革新以及废弃混凝土高效回收利用具有重要的现实意义.研究了采用再生骨料生产的混凝土空心砌块的受压性能,主要包括再生骨料不同级配、粉煤灰掺量以及掺加纤维情况对混凝土空心砌块抗压强度的影响.试验结果表明,通过合理的选择再生骨料、粉煤灰和纤维的掺量,采用再生骨料生产的混凝土空心砌块具有理想的抗压强度,能够用做砌体结构中的承重砌块.     

利用磷矿尾矿砂生产混凝土砖的探讨

尾矿砂粉煤灰混凝土砖具有重量轻、保温、隔热、节能、抗震等特点,适用于工业和民用建筑,特别是适用于高层建筑框架结构填充材料及基础防潮层。     

聚羧酸外加剂制备C30商品混凝土的试验研究

通过调整C30商品混凝土的配合比设计思路,发挥聚羧酸外加剂的高减水作用,降低混凝土中胶凝材料用量及用水量,在保证力学性能的前提下,提高聚羧酸减水剂配制商品混凝土的经济性。     

清水砖墙在工业厂房建筑中的应用

对清水砖墙的外观与性能进行了简单的介绍,以六味斋食品工业园工程为例,阐述了清水砖墙细部策划排砖、砌筑施工、游丁走缝、框架结构及构造柱表面处理等施工工艺方法,并分析了其应用效果,指出清水砖墙不仅典雅、美观,而且绿色、节能、环保。     

Radiological constraints of using building materials and industrial by-products in construction

The advantages of utilization of coal fly ash, phosphogypsum and some other industrial by-products in construction are discussed, as well as the technological and environmental problems caused by an elevated content of chemical/radioactive contaminants. Radiological aspects and legislation issues are analyzed. The tendency to develop stricter environmental norms observed in the last years in both national and international scale is noted. The reasons and possible methods of solving the difficulties with the application of legislation rules and radiation controls in construction industry are discussed. As an example, an experience with the new Israeli Standard 5098 regulating radioactivity in building products is reported. The principles of this standard are analyzed and compared to the Radiological Protection Principles Concerning the Natural Radioactivity of Building Materials Principles of Radiation (Radiological Protection Principles Concerning the Natural Radioactivity of Building Materials, Radiation Protection Report RP-112, EC, European Commission, Luxembourg, 1999) and other existing national standards and guidelines in the field.