钢渣制备透辉石多孔陶瓷的研究

以钢渣、滑石为主要原料,硼酸为助熔剂,SiC为发泡剂,经1 050~1 150℃保温10~20 min制备了透辉石泡沫陶瓷。多孔陶瓷的孔体积分维数与闭气孔率之间存在良好的线性关系。     

纤维增韧泡沫玻璃的制备及性能

以高硅氧玻璃纤维为增韧材料,SiC为发泡剂,废弃的钠钙硅平板玻璃粉为主要原料,采用烧结法成功制备了纤维增韧高强泡沫玻璃.通过DTA、SEM及力学性能测试,分析了试样的特性,定义了泡沫玻璃的比强度特性,应用比强度分析了泡沫玻璃基体中玻璃纤维掺量与试样机械性能的关系.结果表明,基体中加入质量为5％～25％、长度为10～30mm、长径比为100～300的高硅氧玻璃纤维,在790～815℃发泡烧结后,可以制备出比抗折强度为10.45～22.26MPa/(g/cm3),比抗压强度为30.45～34.34MPa/(g/cm3)的纤维增韧泡沫玻璃.所用纤维高强度,高弹性模量,以及纤维在泡沫玻璃基体中纵横交错的结构特征,是构成纤维增强泡沫玻璃机械性能优良的关键因素.     

泡沫混凝土弹性模量的测试方法探讨

为获得密度为800 kg/m3的泡沫混凝土的弹性模量数据,设计了一种振弦式应变计测试的方法,并采用该方法测试了采用普通水泥和双快水泥配制的两种泡沫混凝土的应力应变,绘制了变化曲线,计算了弹性模量.采用普通水泥配制的泡沫混凝土,7 d的弹性模量在200～300MPa之间,采用双快水泥配制的泡沫混凝土,2 h的弹性模量在350～500MPa之间.测试表明该方法操作方便、速度快、测试结果离散性小、数值符合泡沫混凝土的特点和强度水平.     

利用废阴极射线管制备泡沫玻璃及其性能研究

以废旧阴极射线管为主要原料,SiC为发泡剂,Na2SiF6为助熔剂,采用粉末烧结法制备泡沫玻璃。通过DTA、XRD、SEM等分析手段对泡沫玻璃的性能进行了研究。结果表明,发泡剂SiC的最佳用量为5%,配方中加入助熔剂Na2SiF6后,试样的发泡温度降至820℃。试样在发泡温度下保温30 min,主晶相为Pb,次晶相为Pb3O4、Al6Si2O13,泡沫玻璃密度为0.653 g/cm3,抗压强度为6.28 MPa,抗折强度为2.11 MPa。     

发泡原位固凝制备氧化锆泡沫陶瓷研究

以氧化锆粉为基体、AES为发泡剂,采用常温发泡法与固化凝固工艺相结合的方法,制得孔隙均匀细小、强度较高的炉内保温陶瓷材料。通过XRD、TG-DSC、SEM等测试,探索了发泡体系中材料组成以及比例对陶瓷发泡的影响;在1500~1700℃下预烧结,分析了烧成制度对泡沫陶瓷制备过程的影响机理,分析了烧结温度对材料抗压强度和孔隙率的影响。结果表明:AES和氧化锆粉质量比(0.019~0.022)∶1,能制得孔隙率约80%,抗压强度约4.8 MPa,发泡孔隙细小均匀、隔热性能优良的保温陶瓷。     

纤维增强泡沫混凝土性能试验研究

以普通硅酸盐水泥为结合剂,用粉煤灰和微硅粉取代砂和部分水泥制备泡沫混凝土.探讨了微硅粉和聚丙烯纤维对表观密度为800~1 500 kg/m3的泡沫混凝土抗压强度、劈裂抗拉强度、收缩率的影响.结果表明:采用掺加微硅粉和聚丙烯纤维技术,可以制备出表观密度在800~1 500kg/m3,抗压强度达到10~50 MPa的高强泡沫混凝土;微硅粉和聚丙烯纤维能显著提高泡沫混凝土的抗压强度,且泡沫掺量越大,其增强效果越显著;掺入聚丙烯纤维后,泡沫混凝土的劈裂抗拉强度显著提高,干缩率明显下降.     

金属Nb与SiC复合ZrB_2陶瓷的研究

通过添加金属Nb和SiC增韧,制备复合ZrB2陶瓷,采用放电等离子烧结工艺制备Nb-ZrB2二元系统和Nb-ZrB2-SiC三元系统,测试了复合ZrB2陶瓷的硬度、力学性能和微观结构。结果表明所制备的复合陶瓷具有较高的硬度、较高的致密度和良好的断裂韧性,其中添加SiC的三元组分性能更加优越。在1 850℃和1 900℃不同烧结温度下,复合ZrB2陶瓷的韧性都较好,维氏硬度均超过14 GPa。1 900℃下组分Nb(20)-SiC(20)-ZrB2(60)的样品韧性最高,达到3.5 MPa.m1/2。     

生土泡沫混凝土的制备及其性能EI北大核心CSCD

以生土、水泥、聚羧酸减水剂及自制微生物发泡剂为原材料,采用先预制气泡再与水泥浆体混合的方法,制备了不同密度等级的生土泡沫混凝土,研究了泡沫掺量对生土泡沫混凝土干密度、抗压强度、导热系数、吸水率及其孔结构的影响.结果表明:当水泥用量为128.4~583.4 kg/m^(3),生土用量为64.2~291.7 kg/m^(3),减水剂用量为0.6~3.0 kg/m^(3),泡沫掺量为固体材料总质量的6.1%~26.4%时,制成了300~1200 kg/m^(3)密度等级的生土泡沫混凝土,其抗压强度为0.8~10.3 MPa,导热系数为0.08~0.27 W/(m·K),吸水率为6.5%~67.7%,满足泡沫混凝土的相关性能要求.     

煤矿废弃物泡沫陶瓷的物理力学及吸放湿性能

以煤矸石和煤炭伴生页岩为主要原料,滑石粉为助熔剂,抛光渣为造孔剂制备煤矿废弃物泡沫陶瓷.研究不同烧成升温速率对煤矿废弃物泡沫陶瓷表观密度、吸水率、孔隙率、抗压强度、微观孔隙特征及等温吸放湿性能的影响.结果表明:随着烧成升温速率的提高,煤矿废弃物泡沫陶瓷的开口孔隙率降低,吸水率减小,抗压强度提高,平衡含湿量减小.当烧成升温速率为10℃/min时,煤矿废弃物泡沫陶瓷的表观密度小于0.7g/cm3,孔隙率大于70%(体积分数),吸水率约为0.02%(质量分数),抗压强度达到12MPa,在相对湿度97.3%下的平衡含湿量小于0.003 1kg/kg,有利于减少潮湿环境造成的霉菌滋生,降低建筑能耗并营造健康的室内空气环境.     

聚乙烯醇改性泡沫混凝土的实验研究

将一定比例的聚乙烯醇和泡沫掺杂到水泥混凝土中,得到了改性的泡沫混凝土,并从抗压与抗折性能、导热性能以及收缩性能等方面来分析聚乙烯醇对泡沫混凝土性能的影响.研究结果表明:内掺适量的聚乙烯醇,能够显著改善泡沫混凝土的综合性能,其导热系数从初始的0.1075W/m ·K下降到0.085 W/m·K,抗压强度由3.08 MPa增加到3.45 MPa,抗折强度从1.01 MPa增加到1.17 MPa,干密度得到显著降低,为416 kg/m3,且收缩性能得到显著改善.这一研究结果对于聚乙烯醇改性泡沫混凝土在实际应用中提供技术参考.     

纤维增强泡沫混凝土的力学强度及吸水性能

以普通硅酸盐水泥和动物蛋白发泡剂为基材,制备了泡沫混凝土,研究了:试样强度随水灰比、干密度、纤维长度、纤维类型的变化规律;单轴受压下应力应变全曲线;试样微观泡孔分布以及吸水性能的变化。结果表明,素泡沫混凝土和纤维增强泡沫混凝土的抗压强度均随孔隙率增加呈指数减小,水灰比对抗压强度的影响随纤维添加量、孔隙率的不同而不同。短丝纤维对强度的提升优于长丝纤维,网状纤维对强度的改善优于丝状纤维;纤维泡沫混凝土应力应变全曲线包括上升、下降和峰后三段,与素泡沫混凝土相比,其峰值应力对应的峰值应变减小,而弹性模量和残余应力均大幅增加;大直径泡孔占比随纤维添加量增加而降低,添加纤维提升了试样的吸水性能。     

硅砂粉与矿渣微粉复掺技术用于PHC管桩生产

设计研究了管桩生产用的混凝土配合比,将硅砂粉与矿渣微粉作为混凝土掺合料,在满足管桩生产要求前提下,以一定比例取代硅酸盐水泥,采用常压蒸汽养护和高压蒸汽养护,并测定了混凝土的脱模强度及高压蒸汽养护后的强度.试验结果表明,利用硅砂粉和矿渣微粉以一定比例复掺等量代替水泥生产PHC管桩是可行的,其中,复合掺合料的取代比例可达45%,硅砂粉和矿渣微粉的掺量分别为150 kg/m3、50 kg/m3,混凝土脱模及压蒸后的抗压强度分别为49.1MPa、89.0MPa,符合管桩国家标准要求.     

Effect of crushed ceramic and basaltic pumice as fine aggregates on concrete mortars properties

This study examines the suitability of ceramic industrial wastes and huge amounts of basaltic pumice as a possible substitute for conventional crushed fine aggregates. Experiments were carried out to determine abrasion resistance, chloride penetration depths and the compressive strengths of concrete with crushed ceramic waste and basaltic pumice fine aggregates and to compare them with those of conventional concretes. Test results indicated that ceramic wastes and basaltic pumice concretes had good workability. Furthermore, it was found that abrasion resistance of crushed ceramic (CC) and crushed basaltic pumice (CBP) concretes was lower than that of conventional concretes. Test results also showed that maximum abrasion rate was obtained from specimen control (Mo), while minimum abrasion rate is obtained from M3 (60% crushed ceramic concrete) specimens. Abrasion resistance was increased as the rate of fine CC was decreased. Abrasion resistance of concrete was strongly influenced by its compressive strengths and CC and crushed CBP content. The crushed ceramic addition percentage decreased as the chloride penetration depth increased. Results of this investigation showed that CC and CBP could be conveniently used for low abrasion and higher compressive strength concretes.     

楠竹加筋复合锚杆管材力学性能试验研究

 楠竹加筋复合锚杆是一种应用于土遗址加固工程的新型锚杆,为了解锚杆的工作机制,对其管材楠竹进行力学性能试验,研究竹材的抗压、抗拉、抗弯强度及其影响因素。结果表明：3 a生楠竹块顺纹抗压强度达119 MPa,比5 a生楠竹大;同一根楠竹,取自基部和中部的竹块试样,顺纹抗压强度相当,均小于顶部试样;竹块顺纹、横纹、径向抗压强度分别为98,37和65 MPa,强度差异是由加压方向和竹纤维生长方向之间的关系决定的;竹材的顺纹抗压、抗拉和抗弯强度均与竹材的含水率有关,含水率增大强度降低,当含水率达到一定值时,抗压强度趋于稳定;径高比为1∶1和1∶2的竹筒抗压强度试验以及竹条抗拉强度试验结果表明,竹节对竹筒和竹条的强度有一定的削弱作用。     

Elastic properties of self consolidating concrete

With the advancements in self consolidating concrete (SCC) technologies coupled with the demand for shorter construction schedules, there is a need to evaluate the applicability of predictive equations and non-destructive testing methods to assess SCC’s transient in situ mechanical properties. This study measures the evolution of density, compressive strength, dynamic elastic modulus, and static elastic modulus at day 1, 3, 7, 28, and 56 for SCC mix designs. Outcomes from this study revealed that utilization of the dynamic-to-static elastic modulus ratios in conjunction with ultrasonic pulse velocity measurements can be used to estimate the evolution of SCC’s compressive strength. Furthermore, this study presents the test-to-predicted ratios for the static elastic modulus of SCC mixtures based on predictive equations proposed in ACI363, ACI318/AASHTO, EuroCode2, and Gardner and Lockman. Of the proposed predictive equations, ACI318/AASHTO most closely estimates properties of SCC of compressive strengths greater than 50 MPa, and Gardner and Lockman’s equation for SCC of compressive strengths less than 50 MPa.     

不同温度作用后混凝土强度变化规律的研究

对C20,C40混凝土的标准立方体试件,进行了在高温100℃,300℃,500℃,700℃,900℃作用2 h后自然冷却、静置6 h的抗压强度试验以及在400℃和600℃分别持续加热1 h,2 h,3 h,4 h,5 h后自然冷却、静置6 h的抗压强度试验,分析讨论了不同的高温作用后混凝土材料劣化的机理以及对抗压强度的影响,探讨了抗压强度变化的规律。     

活化掺合料混凝土的研究

从提高混凝土中掺合料用量及有效性出发，对页岩灰、粉煤灰、矿渣、磷渣、天然沸石、粉石英等进行了配比及活化处理，用活化掺合料代替１０％～４０％水泥的不同配合比混凝土的抗压强度和坍落度．与基准混凝土比较，活化掺合料混凝土的坍落度变化不大，早期强度较低，后期强度较高；在应用５５５Ｒ硅酸盐水泥和总胶凝材料量５００ｋｇ／ｍ３条件下，以此系列活化掺合料可制得２８ｄ抗压强度５０～８０ＭＰａ，坍落度３～２２ｃｍ的混凝土．     

Performance of an alkali-activated slag concrete reinforced with steel fibers

This study investigated mechanical and permeability properties at early ages of an alkali-activated slag concrete (AASC) reinforced with steel fibers. The compressive, splitting tensile and flexural strengths, flexural notch sensitivity, pull-out and water absorption properties were evaluated. Test results reveal a reduction of AASC compressive strengths with fiber incorporations. However, splitting tensile and flexural strengths were largely improved with increasing fiber volume, varying from 3.75 to 4.64 MPa and from 6.40 to 8.86 MPa at 28 days of curing, respectively. The properties related to durability performance as water absorption, capillarity and water resistance penetration were enhanced with the steel fibers addition. The results show the enormous potential of AASC as building material with and without steel fiber reinforcement.     

Mechanical properties of concrete with recycled coarse aggregate

This paper reports the results of an experimental study on some of the mechanical properties of recycled aggregate concrete (RAC) as compared to those of the conventional normal aggregate concrete (NAC). Ten mixes of concrete with target compressive cube strength ranging from 20 to 50 MPa were cast using normal or recycled coarse aggregates. The development of the cube compressive strength and the indirect shear strength at ages of 1, 3, 7, 14, 28 and 56 days, the compressive strength, the strains at maximum compressive stress and the modulus of elasticity tested by using concrete cylinders at 28 days are reported. The results show that the 28-day cube and cylinder compressive strength, and the indirect shear strength of recycled aggregate concrete were on the average 90% of those of natural aggregate concrete with the same mix proportions. For concrete with cylinder compressive strengths between 25 and 30 MPa, the modulus of elasticity of RAC was only 3% lower than that of NAC. The trends in the development of compressive and shear strength and the strain at peak stress in recycled aggregate concrete were similar to those in natural aggregate concrete.