共查询到20条相似文献,搜索用时 0 毫秒
1.
从碎石集料生产加工、运输、存放等方面,提出沥青中、上面层碎石集料质量控制的几点要求,最大限度的减小原材料对沥青混凝土面层施工质量及耐久性的影响,进而提高沥青路面使用性能。 相似文献
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为了探讨水胶比和碎石体积取代率对次轻页岩陶粒混凝土的物理力学性能影响,通过正交试验得到了LC20最佳配合比,然后再通过不同水胶比(0.30、0.35、0.40)和不同碎石体积取代率rg(0、10%、20%、30%、40%、50%)进行试验,并通过干表观密度、抗压强度、抗折强度、劈拉强度、比强度和折压比,以及断截面破坏形态,探讨其变化规律。结果表明,当碎石取代率为30%,水胶比为0.30时,次轻页岩陶粒混凝土的上述各项指标除折压比外均为最优,并能同步提高强度和韧性,而且还可以有效弥补页岩陶粒产量有限、价格较高和施工性能较差的缺陷。 相似文献
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《Geotextiles and Geomembranes》2020,48(4):539-545
The behaviour and performance of different reinforced slopes during earthquake loading were investigated through a series of shaking table tests. Concrete-canvas and composite reinforcement (geogrid attached to concrete-canvas) were proposed for reinforcing slopes. By considering the effects of different reinforcement methods, the seismic responses of the reinforced slopes were analysed, along with the accelerations, crest settlements, and lateral displacements. The failure patterns of different model slopes were compared using white coral sand marks placed at designated elevations to monitor the internal slide of the reinforced slopes. Both the concrete-canvas and composite reinforcement could increase the safety distance, which ranged from the slide-out point to the back of the model box. The composite reinforcement decreased the volume of the landslide and increased the failure surface angle as a result of the larger global stiffness in the reinforced zone. These results indicate that the recently developed concrete canvas has a better effect on restricting the slope deformation during seismic loading than the nonwoven geotextile reinforcement, and that the use of composite reinforcement could improve the seismic resistance of slopes. 相似文献
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E. S. K. Fekpe 《Construction and Building Materials》1992,6(4):215-218
The design and performance of asphaltic concrete overlays for surface-treated pavements with lateritic gravel bases and subbases using the results of Benkelman beam deflection measurements are discussed. It is found that failure to consider pavement distress factors, local materials and environmental conditions in design are inadequate and early signs of distress are exhibited. It is concluded that the high percentage of unpredictable generated traffic is an important contributing factor to performance. An assessment of stress interaction between the existing surface-treated pavement with granular bases and subbases and the asphaltic concrete overlay needs to be considered in the design process. An appropriate approach would be to consider the overlay design as a new asphaltic concrete-surfaced pavement with granular base and subbase. 相似文献
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针对兰新二线高性能混凝土粗骨料碎石供应不足的问题,通过理论分析卵石破碎后破碎面积占表面积的比例关系及破碎粒径变化趋势,结合试验研究,分析对比了碎卵石对高性能混凝土的影响,得出了碎卵石应用的最小粒径、破碎面积等指标,同时提出了分级破碎的粒径要求,研究即为保证沿线混凝土施工质量提供了理论依据和试验论证,又做到就地取材,节约... 相似文献
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对高速公路所处地区的环境、交通量、地材进行了分析,从地材加工控制,原材料技术指标的控制进行了论述,解决了光圆面过多,针、片含量过大,沥青粘附性不达标,矿料级配差等问题,达到了既满足规范要求,又节约资金、保护环境的效果。 相似文献
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以黏土陶粒、碎石、水泥、Zs-1外加剂等为主要原料,制备了一种高性能陶粒多孔混凝土,通过试验分析了骨料粒径、碎石掺量对陶粒多孔混凝土孔隙率、透水系数、强度等性能的影响,并对其破坏形态、破坏机理进行了分析。结果表明:纯陶粒骨料多孔混凝土的孔隙率为23%~27%,透水系数为6.3~7.1,强度为1~3 MPa在不显著降低孔隙性能的前提下,掺入碎石能有效提高其强度至15 MPa以上;多孔混凝土的强度和孔隙率随骨料粒径的增大而小幅提高,且碎石掺量越大提高效果愈明显。与纯陶粒混凝土相比,碎石掺量为40%~60%、骨料粒径为20~25 mm时,多孔混凝土的强度提高了7倍,而孔隙率仅仅降低了4.2%,此时混凝土基本性能相对最优。 相似文献
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水稳层承担着道路结构的主要承重任务,荷载经面层传至水稳层上,其在整个结构层中起着重要作用。主要以晋城市过境段公路改线路面工程为例,对水稳层相应的施工技术进行探讨、分析,并对施工中相应控制措施进行总结,以期为提升水稳层的施工质量作出贡献。 相似文献
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《Construction and Building Materials》2010,24(7):1129-1133
Self-compacting concrete has significant environmental advantages in comparison to the vibrated concrete: absence of noise and vibrations during installing provides a healthier working environment. In the paper the potential for usage of coarse recycled aggregate obtained from crushed concrete for making of self-compacting concrete was researched, additionally emphasizing its ecological value. On the other hand the issue of the waste disposal sites created by the demolition of old structures is solved. In the experiment, three types of concrete mixtures were made, where the percentage of substitution of coarse aggregate by the recycled aggregated was 0%, 50% and 100%. In the process of mixing, equal consistence of all concrete mixtures was achieved. The obtained results indicate that the properties of these concretes have only a slight difference, and that the recycled coarse aggregate can successfully be used for making of self-compacting concrete. 相似文献
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M. Maslehuddin O.S.B. Al-Amoudi M.K. Rahman M.R. Ali M.S. Barry 《Construction and Building Materials》2009,23(6):2357-2361
This paper reports results of a study conducted to assess the properties of cement kiln dust (CKD) blended cement concretes. Cement concrete specimens were prepared with 0%, 5%, 10%, and 15% CKD, replacing ASTM C 150 Type I and Type V. The mechanical properties of CKD concrete specimens were evaluated by measuring compressive strength and drying shrinkage while the durability characteristics were assessed by evaluating chloride permeability and electrical resistivity. The compressive strength of concrete specimens decreased with the quantity of CKD. However, there was no significant difference in the compressive strength of 0 and 5% CKD cement concretes. A similar trend was noted in the drying shrinkage strain. The chloride permeability increased and the electrical resistivity decreased due to the incorporation of CKD. The performance of concrete with 5% CKD was almost similar to that of concrete without CKD. Therefore, it is suggested to limit the amount of CKD in concrete to 5% since the chloride permeability and electrical resistivity data indicated that the chances of reinforcement corrosion would increase with 10% and 15% CKD. 相似文献
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Properties of autoclaved lightweight aggregate concrete 总被引:1,自引:0,他引:1
Many researches have been carried out on production and properties of pre-cast concretes. Currently, most of them have focused on normal concrete, and are unable to completely represent the behavior of lightweight concrete (LWC). In this study, physical and mechanical properties of LWC produced with diatomite and pumice lightweight aggregates after autoclave curing were investigated. In the production of LWC, 0–4 mm maximum sizes of aggregates were used. Cement content and water/cement ratio were kept at 300 kg/m3 and 0.20, respectively. The specimens were prepared in 50×100 mm cylindrical shape, and after 24 h of demoulding exposed to autoclave curing for 2, 4, 6, 8 and 10 h. Besides, two different cures were applied on the specimens as in water and in air at 20 °C±2, respectively. At the end of autoclaving and environmental cure, compressive strength in 7, 28 and 590 d, unit weight, specific porosity, thermal conductivity and water absorption were tested. Also, microstructures of LWC produced with diatomite and pumice aggregate were investigated. As a result, it is concluded that by autoclaving of specimens in 8–10 h, especially, compressive strength of specimens have increased 75% of strength of 28 aged specimens cured in water. 相似文献
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混凝土面板坝的安全与面板的受力状态密切相关。混凝土面板与砾石垫层料的特性有较大差异,两者之间接触面的力学特性,对于面板的应力与变形具有重要影响。结合国内在建的水布垭高面板堆石坝的设计科研需要,研制了一大型叠环式单剪仪,对面板与砾石垫层间接触面的力学特性进行了试验研究。为了对接触面的不同处理方式的效果进行对比,为设计方案的选择提供依据,分别进行了混凝土面无保护、砂浆保护和乳化沥青保护三种接触面的剪切试验。 相似文献
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Funso Falade 《Building and Environment》1991,26(4):453-458
In this paper, the influence of six curing methods (water, air, moist soil, jute bag, air/water and water/air) on the compressive strength of concrete cube specimens that contain laterite fine aggregate is investigated. Three different mixes of cement, laterite and gravel were used:
; 1:2:4 and 1:3:6 with water/cement ratios of 0.62, 0.75 and 1.02 by weight respectively. Four curing ages of 7, 14, 21 and 28 days were adopted. The results showed that the strength that a particular mix can attain is affected by the curing method used. The water/air curing technique gave the highest strength values of 28.2 Nmm−2 for
Nmm−2 and 17.4 Nmm−2 for 1:2:4 and 1:3:6 mixes respectively, while the air-cured specimens gave the lowest strength values of 17.2 Nmm−2 for
Nmm−2 and 8.0 Nmm−2 for 1:2:4 and 1:3:6 mixes. The higher the cement/aggregate ratio the higher the strength. Generally, there was increase in strength with age irrespective of the mix and the curing technique. 相似文献
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S. Malomo 《Bulletin of Engineering Geology and the Environment》1989,39(1):105-109
Considerable researches have been carried out to demonstrate the importante of microstructure in the interpretation of engineering behaviour of soils. Instances where the investigations are on laterite soils are however scanty in literature. The microstructure of laterite soils obtained from Eastern Nigeria and North-East Brazil, have been examined with the aid of optical and scanning electron microscopes. Investigations reveal the development of the well-known concretionary structure in laterite as a stage by stage process involving the accumulation of sesquioxides. The sesquioxides are accumulated initially as amorphous implantations in the pore spaces, the crystallisation of which leads to bonding of soil elements and formation of concretionary structure. The nature of cementation in the concretionary structure determines the resistance to degradation of the soils grains. The resistance to degradation would in turn influence the engineering behaviour. 相似文献
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M.L. Berndt 《Construction and Building Materials》2009,23(7):2606-2613
The suitability of using more “sustainable” concrete for wind turbine foundations and other applications involving large quantities of concrete was investigated. The approach taken was to make material substitutions so that the environmental, energy and CO2-impact of concrete could be reduced. This was accomplished by partial replacement of cement with large volumes of fly ash or blast furnace slag and by using recycled concrete aggregate.Five basic concrete mixes were considered. These were: (1) conventional mix with no material substitutions, (2) 50% replacement of cement with fly ash, (3) 50% replacement of cement with blast furnace slag, (4) 70% replacement of cement with blast furnace slag and (5) 25% replacement of cement with fly ash and 25% replacement with blast furnace slag. Recycled concrete aggregate was investigated in conventional and slag-modified concretes. Properties investigated included compressive and tensile strengths, elastic modulus, coefficient of permeability and durability in chloride and sulphate solutions. It was determined that the mixes containing 50% slag gave the best overall performance. Slag was particularly beneficial for concrete with recycled aggregate and could reduce strength losses. Durability tests indicated slight increases in coefficient of permeability and chloride diffusion coefficient when using recycled concrete aggregate. However, values remained acceptable for durable concrete and the chloride diffusion coefficient was improved by incorporation of slag in the mix. Concrete with 50% fly ash had relatively poor performance for the materials and mix proportions used in this study and it is recommended that such mixes be thoroughly tested before use in construction projects. 相似文献