闪长岩作水泥混合材的研究

对天然矿物原料闪长岩作水泥混合材进行了初步研究，测定了闪长岩的化学组成与矿物组成，及其火山灰活性，并分析了闪长岩不同掺量对水泥物理力学性能的影响。结果表明，闪长岩具有火山灰活性，只是发挥得较慢，其对于水泥混凝土耐久性的影响有待以后进一步的研究。     

火山灰质粉对砂浆性能与微结构的影响

为加强我国区域火山灰资源利用，为工程建设提供优质建筑原材料，选取泸定桥、泸霍两地典型火山灰弃岩资源磨制成火山灰材料，研究不同种类和粒径的火山灰质材料基本特性。采用火山灰等质量取代水泥制备火山灰-水泥砂浆，分析火山灰对水泥砂浆力学性能与微观结构的影响及机理。结果表明，随着火山灰粒径（d50）的降低，砂浆各个龄期的抗压强度和火山灰活性指数升高，但浆体的流动性降低。掺入火山灰会导致浆体的孔隙率增大和孔结构粗化。当火山灰粒径相似时，泸定桥组砂浆的28d活性指数小于泸霍组。此外，蒸汽养护可以促进各组砂浆的抗压强度和活性增长。     

流化床燃煤固硫渣火山灰活性评定的探讨

流化床燃煤固硫渣是一种特殊的、具有火山灰活性的燃煤副产品,由于其f-CaO和SO3含量较普通煤粉锅炉灰渣高,具有一定的自硬性和膨胀性,目前尚无统一的方法或标准准确评定其火山灰活性,影响了该燃煤副产品的建材资源化利用。根据流化床燃煤固硫渣火山灰活性来源及其特点,参照《用于水泥中的火山灰质混合材料》GB2847和《用于水泥混合材料的工业废渣活性试验方法》GB12957-91,提出采用“水泥熟料胶砂28天抗压强度比”来评定流化床燃煤固流渣的火山灰活性。试验研究表明该方法测定的火山灰活性与其自硬性强度和活性率具有较好的一致性。     

磷渣粉火山灰活性研究

粒化磷渣是活性渣，采用火山灰效应比强度、火山灰效应强度贡献率、活性指数等定量指标以及火山灰效应图，来准确地判断与分析磷渣粉掺合料在水泥石中的火山灰效应的大小、影响因素及其规律。结果表明，磷渣水泥石的火山灰效应比强度、火山灰效应强度贡献率、活性指数等均随着磷渣粉的掺量和龄期的增加不断增大，其中在水化早期磷渣粉的火山灰效应呈现负效应。     

养护条件对陶瓷抛光砖粉-石灰胶凝材料强度的影响

以废弃陶瓷抛光砖粉为辅助胶凝材料制备蒸压硅酸盐制品,研究比表面积、养护制度等因素对制品强度的影响;测试蒸压处理前后抛光砖粉中活性硅、铝含量;对不同比表面积以及蒸压处理前后的抛光砖粉进行FTIR测试,对比分析其化学结构的变化。结果表明:增大比表面积、提高养护温度,均可激发抛光砖粉的火山灰反应活性,增加制品强度。养护温度对抛光砖粉的火山灰活性激发的影响作用较强。与未经处理的抛光砖粉相比,蒸压处理可增加抛光砖粉的活性硅、铝含量,提高抛光砖粉火山灰反应能力。与试验用Ⅱ级粉煤灰相比,蒸压处理对抛光砖粉的活性激发作用要强于试验用Ⅱ级粉煤灰。     

I级粉煤灰火山灰反应性研究

研究了经电收尘及分选的I级粉煤灰火山灰反应性，探讨了其对水泥基材料强度的影响。结果表明：相比于Ⅱ级粉煤灰，I级粉煤灰火山灰活性未必更高；不同品质粉煤灰活性上的差异在宏观上对水泥砂浆强度影响甚微。     

高炉渣超细粉火山灰活性评价方法研究

利用Frattini试验法、石灰吸收法、电导率法和活性指数法研究了四种不同细度高炉渣超细粉的火山灰活性。结果表明,四种方法均可反映不同细度高炉渣超细粉火山灰活性的高低。其中石灰吸收法和电导率法存在一定缺陷,仅限实验室使用;Frattini试验法可以定量火山灰反应中氧化钙的消耗量;活性指数法则可直接体现水泥胶砂强度变化情况。可见,Frattini试验法和活性指数法可靠性较高,是评价高炉渣超细粉火山灰活性的重要手段。     

火山渣的活性研究

采用火山灰活性图法及抗压强度比法评价了火山渣的活性,并对火山渣的活性影响因素及活性提高方法进行了研究。结果表明:试验采用的2种火山渣均具有火山灰活性;超细粉磨或化学激发可提高火山渣的火山灰活性,与比表面积为520 m2/kg的火山渣相比,比表面积为1022 m2/kg的火山渣的3 d抗压强度比提高了16.7%,28 d抗压强度比提高了12.2%;掺加适量的CaCl2、CaO或Ca(OH)2可以提高火山渣水泥的3 d抗压强度,掺加适量CaSO4可以提高火山渣水泥的28 d抗压强度。     

应用比强度指标研究活性矿物掺料在水泥与混凝土中的火山灰效应

本文提出了单位熟料或单位水泥对掺有活性矿物掺料的水泥或混凝土的强度贡献概念，定义了水泥单位熟料比强度和混凝土单位水泥的比强度指标，水泥或混凝土土中的火山灰效应比强度，比强度系数及火山效应强度贡献率，并绘制火山灰效应图，利用这些指标及火山灰产应图，能定量地分析掺有活性矿物掺料的水泥与混凝土在硬化过程中火山灰效应的大小，影响因素及规律性。     

珍珠岩粉火山灰活性研究

为促进珍珠岩作为水泥基辅助胶凝材料应用，分别采用化学分析活性组分的活性率法、XRD法、砂浆强度比的活性指数法定量分析评判珍珠岩粉火山灰活性大小，并讨论其影响因素．珍珠岩粉化学分析活性组分硅和铝量占全部硅和铝量百分率即活性率32．95％，与沸石粉的相当但低于硅灰的；通过珍珠岩粉XRD{2132}峰半高宽法测定非晶态SiO2含量而计算得其火山灰活性55．23％；以砂浆强度比表述的活性指数研究显示两种细度珍珠岩粉达到国家标准中沸石粉的要求，掺30％珍珠岩粉的活性指数均大于火山灰活性界值0．62．尽管各种方法测试的珍珠岩粉火山灰活性表征参数及其结果有差异，但都可得出珍珠岩粉有较高火山灰活性的结论，其火山灰活性还受SiO2和AlO3含量、结构非晶态的比率、粉末细度、水化环境等因素影响．     

Development of corn cob ash blended cement

In an attempt to convert waste product into useful material for the construction industry, this research considered the use of corn cob ash (CCA) as a pozzolan in cement production. The study investigated the chemical composition of CCA. Factory production of the CCA – blended cement was carried out by replacing 0%, 2%, 4%, 6%, 8%, 10%, 15%, 20% and 25% by weight of Ordinary Portland Cement clinker with CCA. The 0% replacement serves as the control. The results showed that CCA is a suitable material for use as a pozzolan as it satisfied the minimum requirement of combined SiO₂ and Al₂O₃ of more than 70%, which a good pozzolan for manufacture of blended cement should meet. The blended cements produced also satisfied both NIS 439:2000 and ASTM C 150 requirements especially at lower levels (<15%) of CCA percentage replacement. Based on the test results, it was concluded that CCA could be suitably used in blended cement production.     

Strength–porosity relationships in lime–pozzolan mortars

Lime–pozzolan mortars are the hydraulic mortars widely used in the past for the construction of monumental structures and nowadays for their repair. These mortars are of higher porosity and lower strength in comparison with cement-based mortars but they have exhibited noticeable durability. For the design of lime–pozzolan mortars it is important to know the fundamental strength–porosity relationship as well as the parameters influencing the porosity since it is the driving factor for the functional behaviour of the mortar and its resistance to aging. In this research, an adequate number of mortar series were prepared and tested to find the effect of water/binder (w/b) ratio, the aggregate volume content, the evolution of porosity with time and formulate the strength–porosity relationship based on Power’s basic mathematical expression. According to results it seems that the water/binder ratio is the most important parameter influencing the porosity. Strength–porosity relationship can be predicted with an acceptable deviation. Porosity of lime–pozzolan mortars decreases with time and it is strongly influenced by the curing conditions.     

The reduction of indoor air pollutant from wood-based composite by adding pozzolan for building materials

The purpose of this study was to investigate the physico-mechanical properties and characteristics on reduction of formaldehyde and total volatile organic compound (TVOC) emission from medium density fiberboard (MDF) as furniture materials with added volcanic pozzolan. Pozzolan was added as a scavenger to urea formaldehyde (UF) resin for MDF manufacture. The moisture content, density, thickness swelling, water absorption and physical properties of MDFs were examined. Three-point bending strength and internal bond strength were determined using a universal testing machine. Formaldehyde and TVOC were determined by desiccator and 20 L small chamber methods as Korean standards method. With increasing pozzolan content the physical and mechanical properties of the MDFs were not significantly changed, but formaldehyde and TVOC emissions were decreased. Because pozzolan has a rough and irregular surface with porous form, it can be used as a scavenger for MDFs without any detrimental effect on the physical and mechanical properties.     

Effect of adding mineral additives to alkali-activated natural pozzolan paste

Natural pozzolans are raw materials from geological deposits with a range of chemical compositions that when combined with suitable alkali activators can be converted to geopolymer cement for concrete production. In this paper the concept of adding mineral additives to enhance the properties of geopolymer cement is introduced. Taftan andesite, a natural Iranian pozzolan, was used to study the effect of adding mineral additives such as kaolinite, lime and other calcined pozzolans on the compressive strength of geopolymer cement under both normal and autoclave curing. Scanning electron microscopy (SEM)/energy dispersive X-ray (EDX) was used to determine the composition of the gel phase in both alkali-activated Taftan pozzolan with and without mineral additions. The work has shown that deficiencies in SiO₂, Al₂O₃ and CaO content in the raw natural pozzolan can be compensated for by adding mineral additives for enhanced properties.     

Study of the hydration process of quaternary blended cements and durability of the produced mortars and concretes

This study aims to clarify the effect that blended cements with four components have on the hydration process and durability of concrete. Therefore, blended cements with two different proportions of high calcium fly ash, natural pozzolan and limestone have been produced and have been compared with CEM I. Compressive strength was measured at different ages and the hydration kinetics was studied by means of proton nuclear magnetic resonance (NMR-H). Furthermore, the above mentioned cements have been used to produce mortars and concretes and their durability have been determined. The aspects of durability that has been determined are: pore size distribution by means of NMR-H and mercury intrusion porosimetry, penetration of chlorides, carbonation and resistance to sulfates attack. The conclusion of the present study is that quaternary blended cements can perform as well as CEM I cement as far as compressive strength are concerned and they produce durable mortars and concretes.     

Compressive strength and shrinkage of mortar containing various amounts of mineral additions

Three mineral additions largely used in cementitious materials were tested in order to follow the shrinkage behaviour for 1 year of observation when they substitute a part of cement. The tests were carried out on standardized mortars specimen where cement was replaced by 5%, 15% and 25% of limestone, 10%, 20%, 30% of natural pozzolan and 10%, 30% and 50% of slag. The substitution of cement by 10%, 20% and 30% of limestone powder, natural pozzolan and slag respectively involves an optimal improvement of compressive strength of mortar. The separate quantification of the autogeneous and drying shrinkage development shows the effective contribution of each addition on microstructure modification and of the additional hydrates production. The microstructure was improved in the presence of limestone and of a moderate rate of slag, whereas it remains normal with natural pozzolan. The replacement rate of an active addition lower than 10% led to an additional hydrates production. This overproduction which accompanies the autogeneous shrinkage is more pronounced when cement is largely replaced by limestone. The evolutions of strength and shrinkage of mortars follow the same tendency from where it is easier to find a linear relationship giving the shrinkage deformation according to the compressive strength.     

Chemical–physical behaviour of matt waste in cement mixtures

The chemical and physical behaviour of matt waste (MW), a by-product which derives from purification processes of cullet from separated glass waste collection, has been studied as new component for cement based materials. Up to now, recycling for MW is not fully exploited. The aim of this research is to investigate the possible benefits of MW addition to cement systems. Investigations on paste samples cured in accelerated conditions were carried out with different analytical techniques (FT-IR, TGA, SEM, MIP) to investigate MW reactivity with portlandite and its effect on pastes microstructure. The results highlight pozzolan behaviour of MW at long curing time and a refinement of porosity leading to a compact microstructure.     

Assessing the effectiveness of pozzolans in massive high-strength concrete

This paper investigates the effects of supplementary cementitious materials on the temperature rising profile, heat evolution and early-age strength development of medium- and high-strength concrete. A total of 13 different mixtures were prepared, with two water–cement ratios (0.3 and 0.46). Natural pozzolan, fly ash, and silica fume were included in the specimens. The results showed that natural pozzolan, particularly fly ash served to decrease the amplitude of peak temperature, delay the occurrence of the peak, and decrease the sharpness of the temperature rising profiles. In contrast, the temperature profile of silica fume specimens was similar to those without silica fume. It was found that the best mixture, the highest early-age strength and the lowest heat liberation, corresponded to the specimen containing fly ash at 15% (be cement weight). This result justifies the advantage effect of fly ash which is able to develop sufficient tensile strength to resist thermal cracking potential in massive high-strength concrete.     

Effect of heat treatment on reactivity-strength of alkali-activated natural pozzolans

Natural pozzolans can be activated and condensed with sodium silicate in an alkaline environment to synthesize high performance cementitious construction materials with low environmental impact. The nature of the starting materials including mineral composition, chemical composition and crystal structure groups affects the formation of the geopolymer gel phase. In this paper, the pozzolanic activities of five natural pozzolans are studied. From XRD and XRF results, most of the raw materials contain zeolite clay minerals and have a high loss on ignition. Therefore, before use, samples were calcined at 700, 800 and 900 °C, respectively. The improvement in pozzolanic properties was studied following heat treatment including calcinations and/or elevated curing temperature by using alkali solubility and compressive strength tests. The results show that pozzolan containing sodium zeolite clinoptilolite can be used to prepare a moderate to high strength binder by heat treatment and calcinations can impart disorder hornblende as a constituent of pozzolan with no amorphous phase to prepare a moderate strength binder.