共查询到19条相似文献，搜索用时 254 毫秒
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为了研究补偿收缩混凝土的抗冻性能,采用慢冻法对普通混凝土和补偿收缩混凝土进行冻融对比试验。通过对比研究普通混凝土和补偿收缩混凝土冻融后质量损失、强度损失和相对动弹性模量变化趋势,从而得出补偿收缩混凝土的抗冻性能。试验结果表明,普通混凝土冻融100次后,质量损失率为2.09%,抗压强度下降35.2%,相对动弹性模量下降到60.8%;补偿收缩混凝土质量损失率为1.62%,抗压强度下降30.3%,相对动弹性模量下降到64.8%;试验三个参数指标表明添加膨胀剂有助于提高混凝土抵抗冻融破坏的能力,改善混凝土结构的损伤程度,体现了膨胀剂对混凝土的增强机理。 相似文献
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以硅酸盐和硫铝酸盐复合水泥为基材制作水泥基注浆材料,分别讨论了不同类型、不同掺量的粉煤灰和矿粉对水泥基注浆材料的流动度、容重、膨胀率、抗压抗折强度的影响。结果表明:粉煤灰能有效地增加水泥基注浆料的流动度,当粉煤灰掺量低于20%时,可以提高注浆料的塑性膨胀率,当Ⅰ级粉煤灰掺量为20%或Ⅱ级粉煤灰掺量为15%时,3 h膨胀率最高达1%;粉煤灰对注浆料的早期强度不利,但可以增强其后期强度。矿粉可以改善其流动度,随着矿粉的增加,注浆料的容重和膨胀率均呈下降趋势;矿粉对注浆料的28 d强度无显著影响,其早期强度随着矿粉的增加而下降,当S75矿粉掺量高于7%或S95矿粉掺量高于11%时,抗压抗折强度不满足规范要求。 相似文献
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《实验室研究与探索》2020,(4):42-45
为提高混凝土材料的抗压强度、抗折强度、吸水性和软化性,以石膏、沸石粉和碳纤维为掺合料,按照不同比例掺和,并测定混合物各项性能。通过实验得出:随着石膏掺量的增加,混凝土材料抗压、抗折强度先增加后降低;随着沸石粉掺量的增加,混凝土复合材料的抗压强度和软化系数逐渐增加,但吸水率却逐渐减小。掺入碳纤维后,混凝土材料的各项性能指标变化趋势和机理与掺入沸石粉时类似,但碳纤维的作用效果较沸石粉好。因此,建议高性能混凝土材料中石膏掺量为30%、沸石粉掺量为12%或碳纤维掺量为10%。 相似文献
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为了测定耐碱玻璃纤维混凝土的抗折强度并分析其不确定度及纤维体积率对混凝土抗折强度的影响,选择耐碱玻璃纤维体积率为0%0,.6%,0.8%,1.0%的100 mm×100 mm×400 mm混凝土抗折试件进行试验。试验在MTS810材料试验机上进行,通过三分点加载测定其抗折强度,分析混凝土抗折强度试验中影响试验结果不确定的因素和来源,并按照JJF 1059-1999标准的要求,对合理玻璃纤维掺量试件的抗折强度的不确定度进行分析和评定。结果表明:耐碱玻璃纤维的掺入改变了混凝土抗折破坏形式,不同纤维体积率的混凝土抗折强度较普通混凝土依次提高了18.87%,21.64%,23.24%。综合考虑各方面因素确定耐碱玻璃纤维混凝土合理玻璃纤维掺量为0.6%;通过对试件抗折强度测定的不确定度评定,表明数学模型中自由度及测量的重复性是引入测量结果不确定度的主要因素;建议在进行同类试验时,试件尺寸应尽量大,从而可增大跨距,以减小剪力对测量结果的影响。 相似文献
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在普通混凝土中掺入PFAC明显改善普通混凝土的和易性,且具有显著的缓凝作用,使混凝土坍落度的经时损失减小,随着PFAC掺量的增加,水泥净浆的初凝和终凝时间随之延长,混凝土早期强度下降的幅度也随之增大,PFAC对混凝土的后期强度有着显著的增强效应．配制的掺PFAC混凝土28d的抗折强度超过5．0MPa,均能满足重交通和特重交通开放交通的要求,该混凝土的拉压比、折压比比普通混凝土有一定提高,试验结果为普通混凝土高性能化提供了技术保障。 相似文献
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钢纤维混凝土试验与施工应用 总被引：1，自引：0，他引：1
本文通过对钢纤维混凝土试验分析 ,探讨满足施工要求的钢纤维混凝土配合比 ,通过室内试验与室外施工比较 ,钢纤维混凝土比普通混凝土在抗压、抗折、抗渗、抗弯等方面均有较人提高 ,在桥面辅装上应用提高了桥面铺装的强度和耐久性 相似文献
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以超细钢铁渣粉(以下简称“超细钢渣”) 为主要掺合料制备胶凝材料,通过XRF、粒径分析、XRD分析和力学性能测试,探究超细钢渣对水泥基材料的力学性能影响。结果表明:通过机械研磨制备出的超细钢渣,其矿相成分硅酸三钙、硅酸二钙和莫来石特征峰强度最强,复掺的超细钢渣活性指数也满足国家标准。随着超细钢渣掺量增加,3 d 抗压和抗折强度均出现逐渐降低的趋势,但在外掺m (超细钢渣) ∶ m (超细矿渣)= 2:3、w复合粉=30%时,其28 d 抗压和抗折强度达到峰值,分别为8.9、53.8 MPa。超细钢渣在不同龄期水化反应程度不同,早期水化反应较低,强度较差;后期水化程度较高,且优于同标准水泥。 相似文献
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Super absorbent polymers (SAPs) are gradually being applied in concrete production as internal curing agents.SAP can effectively reduce early age autogenous shrinkage of concrete,alleviate the hazards caused by concrete cracking and improve its freeze–thaw resistance.However,the relationships between SAP dosage,SAP particle size and the water–cement ratio of concrete have certain influences on the evolution of the compressive strength of SAP-incorporated concrete.In this study,experiments were conducted to investigate the relationships between the water–cement ratio of concrete,the SAP dosage and SAP particle size.The significant factors influencing concrete strength are determined and equations are proposed for predicting the strength of SAP-incorporated concrete at 3,7 and 28 days.The findings from this study,such as the SAP dosage should not be larger than 0.2%,are expected to form a theoretical basis for the rational use of SAP as an additive to concrete. 相似文献
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混凝土冻融耐久性的试验研究 总被引：2，自引：0，他引：2
以混凝土冻融耐久性为研究内容，用不同种类混凝土的抗压强度、动弹性模量、超声波声速等指标的损失率来表征冻融过程中混凝土的性能劣化状况，并系统比较了不同种类混凝土的抗冻性优劣．通过研究得出：无论是普通混凝土，还是高强混凝土或高性能混凝土，其动弹模损失率、抗压强度损失率、超声波声速损失率均随冻融次数的增加而增大；提高混凝土强度在一定程度上可以提高混凝土抗冻融性能；掺入高效减水剂、优质引气剂和优质掺合料等，高性能混凝土抗冻融性能比对应的基准混凝土性能显著改善，而且通过这样的技术措施，较低强度等级的混凝土也可以获得高抗冻性．鉴于超声波测试方法方便、快捷、准确。而且可以直接用于实际工程的混凝土性能检测，所以，与动弹模测试方法相比，采用超声波测试技术来评价实际工程中混凝土的耐久性劣化程度具有明显的优势． 相似文献
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再生混凝土力学性能的研究 总被引：1，自引：0，他引：1
对再生混凝土力学性能的研究进行了综述，主要包括再生混凝土力学性能的抗压强度、弹性模量、干缩与徐变。研究表明，和普通混凝土相比，再生混凝土力学性能的抗压强度低，弹性模量小，干缩与徐变较大。最后提出了再生混凝土力学性能需要进一步研究的问题。 相似文献
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通过设计在不同配合比的人工砂和天然砂试验,定性的找到了不同配比与人工砂混凝土抗压强度及干缩性的关系曲线。实验研究结果表明,随着人工砂掺量的增加,人工砂混凝土抗压性能有明显的提高,但是其干缩性能越差。因此,人工砂与天然砂的配合比为3:2时,C40人工砂混凝土有较好的抗压性能和干缩性能,能够达到相应规范的硬性指标。 相似文献
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Lightweight aggregate concrete cube specimens (100 mm×100 mm×100 mm) and plate specimens (100 mm×100 mm×50 mm) were tested under biaxial compression-compression (CC) and compression-tension (CT) load combinations. For comparison, normal concrete plate specimens (100 mm×100 mm×50 mm) were tested under the same load combinations. Based on the test results, a two-level strength criterion of lightweight aggregate concrete in both octahedral stress coordinate and principal stress coordinate was suggested. The lightweight aggregate concrete cube specimens (100 mm×100 mm×100 mm) were then tested under triaxial compression-compression-compression (CCC) load combination with corresponding tests on normal concrete cube specimens (100 mm×100 mm×100 mm). The effect of intermediate principal stress on triaxial compressive strength is further examined. A "plastic flow plateau" area was apparent in principal compressive stress-strain relationships of lightweight aggregate concrete but not in normal concrete. A quadratic formula was suggested for the expression of strength criterion under triaxial compression. 相似文献
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SUJI D. NATESAN S. C. MURUGESAN R. 《浙江大学学报(A卷英文版)》2007,8(7):1101-1109
Synthetic fibers made from nylon or polypropylene have gained application when loose and woven into geo textile form although no information on the matrix＇s mechanical performance is obtained so that more understanding of their structural contribution to resist cracking can be determined. This paper presents the results of an experimental investigation to determine the performance characteristics of concrete reinforced with a polypropylene structural fiber. In this investigation ＂Fiber mesh＂ brand of fibers manufactured by SL Concrete System, Tennessee, USA and marketed by M/S Millennium Building System, Inc., Bangalore, India are used. The lengths of the fibers used were 24 mm. Fiber dosages used were 0.9, 1.8, 2.7 kg/m^3. A total of three mixtures, one for each fiber dosage were made. A standard slump cone test was conducted on the fresh concrete mix with and without fibers to determine the workability of the mix. The test program included the evaluation of hardened concrete properties such as compressive, split tensile, modulus of rupture and flexural strengths. The increase in compressive strength is about 36.25%, 26.20%, and 23.75% respectively that of plain concrete. This increase in strength was directly proportional to amount of fibers present in the mix. The increase in flexural strength for Mixes I-III is about 21%, 16.6%, and 23% respectively that of plain concrete specimens. An experimental investigation was also made to study the behaviors of reinforced fibers concrete beams （with longitudinal reinforcements） under two-point loading. The deflection and crack patterns were also studied. The improvements in strength and ductility characteristics were discussed. 相似文献
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The properties of two types of fly ash geopolymers made from class F fly ashes produced in wet bottom and dry bottom boilers were investigated in the present study. The source material used in the geopolymer concrete was activated with sodium hydroxide and sodium silicate solution. The results revealed that the geopolymer produced with wet bottom boiler fly ash(CZ-FA)hardened quickly, and had higher early-age strength and lower shrinkage than the geopolymer produced with dry bottom boiler fly ash(SX-FA). The compressive strength of the two geopolymers made from CZ-FA and SX-FA was 45 MPa and 15 MPa respectively when cured at 60 ℃ and delayed for 14 d. However, after 90 days' delay, the compressive strength of both the samples is almost the same, up to 80 MPa. Nearly 20% volume shrinkage of the samples made from SX-FA was much higher than that made from CZ-FA, which was almost zero. XRD, SEM/EDS and FT-IR were used to analyze the main reason of the differences. 相似文献
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研究了玄武岩纤维长径比对混凝土立方体抗压强度、劈裂抗拉强度及抗折强度的影响。结果发现:玄武岩纤维的掺入有利于提高混凝土强度,但纤维长径比不同,对强度的改变程度不同。玄武岩纤维对混凝土立方体抗压强度提升幅度最小,最高为8.1%,较适宜纤维长径比在800:1~1200:1之间;对混凝土的劈裂抗拉强度提升幅度最大,最高为23.8%,对混凝土的抗折强度提升幅度居中,最高为15.8%,最优纤维长径比均在1200:1~1600:1之间。为提高混凝土强度,长径比相对较大的纤维应适当降低纤维体积率,长径比相对较小的纤维可适当增加纤维体积率,但不宜超过0.15%。 相似文献