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1.
回弹法检测早龄期高性能混凝土强度技术研究 总被引：3，自引：0，他引：3
根据山东泰安地区原材料的实际情况，介绍了高性能混凝土（HPC）非破损方法的选择和相关关系方程的确定，按照高性能混凝土配合比的确定原理，试验并确定了适宜的配合比，建立了高性能混凝土（HPC）7d抗压强度及回弹值推定28d抗压强度的经验公式，并对其适用范围作了说明。 相似文献
2.
为了满足严寒地区水利工程的抗冲磨要求,开展了掺加引气剂、HF抗冲磨剂等外加剂,研究了水胶比、粉煤灰掺量、HF抗冲磨剂掺量对高性能混凝土抗冲磨性能的影响,以期为今后的类似工程提供一定的参考价值。研究表明：粉煤灰掺量在15%～25%时,高性能混凝土的抗冲磨强度变化趋势是先升后降,说明掺入适量的粉煤灰是可以提高抗冲磨强度的;HF抗冲磨剂能显著提高高性能混凝土的抗冲磨性能,但掺量并不是越大越好,有一个最优掺量;混凝土的抗冲磨强度随着水胶比的降低而增大,但水胶比若过小,则抗冲磨强度反而会降低。 相似文献
3.
试验选用体重在33kg左右、公母各半的三元杂交(杜×长×大)生长猪96头,按体重随机分成3个处理,每个处理4个重复,每个重复8头猪进行为期42d的生长试验。试验处理为:普通玉米组,高蛋白玉米Ⅰ组,高蛋白玉米Ⅱ组(减少豆粕比例组)。研究在等比例和等蛋白条件下分别用高蛋白玉米替代普通玉米对猪生产性能的影响。试验结果为:高蛋白玉米Ⅰ组的日增重略高于普通玉米组,料重比稍低于普通玉米组,但差异均不显著;高蛋白玉米Ⅱ组的日增重稍低于普通玉米组,料重比略高于普通玉米组,差异也都不显著。试验结果表明,在生长猪日粮中使用高蛋白玉米,具有一定的促生长作用和减少豆粕等蛋白质饲料的用量、降低饲料成本的潜力。 相似文献
4.
羟丙基纤维素接枝甲基丙烯酸丁酯共聚物的合成与表征 总被引：1，自引：0，他引：1
采用羟丙基纤维素（HPC）与甲基丙烯酸丁酯（BMA）为原料,通过乳液接枝共聚反应成功合成羟丙基纤维素接枝聚甲基丙烯酸丁酯共聚物（HPC-g-PBMA）。利用红外光谱（IR）、X-射线衍射（XRD）和扫描电镜（SEM）对合成接枝产物进行了结构表征,测试了HPC-g-PBMA的溶解性能,利用热重分析（TG）、示差扫描量热分析（DSC）对合成接枝产物的热性能进行了分析。结果表明,HPC-g-PBMA的结构及表观形貌较HPC发生了改变,热塑性能得到增强并具有良好的抗强酸、抗强碱和抗有机溶剂侵蚀性能。通过正交试验设计,确定了该合成反应的最佳反应条件。图9表7参18 相似文献
5.
Petra Scanferla Giorgio Ferrari Roberto Pellay Annamaria Volpi Ghirardini Gabriele Zanetto Giovanni Libralato 《Journal of Soils and Sediments》2009,9(3):229-236
Background, aim, and scope
An innovative stabilization/solidification (S/S) process using high-performance additivated concrete technology was developed for remediating soil contaminated by metals from abandoned industrial sites. In order to verify the effectiveness of this new ex situ S/S procedure, an area highly contaminated by metallic pollutants (As, Cd, Hg, and Pb), due to the uncontrolled discharge of waste generated from artistic glass production on the island of Murano (Venice, Italy), was selected as a case study. The technique transforms the contaminated soil into an aggregate material suitable for reuse as on-site backfill. This paper reports the main results of the demonstration project performed in collaboration with the local environmental protection agency (ARPAV).Materials and methods
An ex situ treatment for brownfield remediation, based on the transformation of contaminated soil into very dense, low porous, and mechanically resistant granular material, was set up and tested. Specific additives (water reducers and superplasticizers) to improve the stabilized material properties were developed and patented. A demonstration plant assembled on the study area to treat 6 m3 h–1was then tested. After excavation, the contaminated soil was screened to remove coarse material. The fraction Ø?>?4 mm (coarse fraction), mainly composed of glass, brick, concrete, and stone debris, was directly reused on site after passing through a washing treatment section. The highly polluted fraction Ø?≤?4 mm (fine fraction) was treated in the S/S treatment division of the plant (European patent WO/2006/097272). The fine fraction was mixed with Portland cement and additives defined on the basis of the high performance concrete technique. the mixture was then granulated in a rolling-plate system. After 28 days curing in an onsite storage area to allow for cement hydration, the stabilized material was monitored before its in situ relocation. The chemical, mechanical, and ecotoxicological reliability and performance of the treatment was checked. Metal leachability was verified according to four leaching test methods: Italian Environmental Ministry Decree (1998), EN 12457 (2002) tout court, amended only with MgSO4 and, lastly, with artificial sea water. The mechanical properties were measured according to BS (1990) and AASHTO (1999) to obtain the Aggregate Crushing Value and California Bearing Ratio, in that order. Moreover, leachate samples prepared with artificial seawater were assessed via the Crassostrea gigas embryotoxicity test and Vibrio fischeri bioluminescence inhibition test to discriminate the presence of potential ecotoxicological effects for the brackish and saltwater biota.Results
Outcomes from all leachate samples highlighted the effectiveness of the remediation treatment, fully complying with the Italian legislation for non-hazardous material reuse under a physicochemical viewpoint. The stabilized granular material demonstrated high mechanical strength, low porosity, and leachability. Moreover, ecotoxicological surveys indicated the presence of low toxicity levels in leachate samples according to both toxicity tests.Discussion
Remediated soil samples revealed a significant decrease in leachability of heavy metals as a consequence of the application of additivated cement that enhanced granular material properties, resulting in improved compactness due to the reduction in water content. The toxicity data confirmed this state-of-the-art technique, indicating that leachates could be deemed as minor acutely toxic.Conclusions
The proposed S/S treatment proved to be able to remediate soil contaminated by heavy metals through trapping pollutants in pellet materials presenting adequate physicochemical, mechanical, and ecotoxicological properties in order to prevent leachability phenomena, their reclamation, and reuse being made easier by its granular form.Recommendation and perspectives
This project foresees long-term monitoring activity over several years (until 2014) to consider treatment durability. 相似文献6.
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在对北方某市进行大量水质调研的基础上,分析了细菌总数(Heterotrophicplatecount,HPC)与温度、余氯、三氯甲烷、可同化有机碳(assimilableorganiccarbon,AOC)、磷的关系。研究表明:温度是影响细菌总数的关键性因素;细菌总数随总余氯的减少而急剧增加;三氯甲烷与细菌再生长有一定的相关性;AOC与细菌总数相关性不高,不能仅用AOC来评估管网的生物稳定性;总磷与细菌总数有很好的相关性,可以作为该市水质生物稳定性的标志,水厂可通过工艺的改进来控制TP<3μg/L,以达到水质的生物稳定性。 相似文献
8.
硅粉粉煤灰双掺高性能混凝土的配制及其应用 总被引：1，自引：0，他引：1
在实验的基础上研究了硅粉、粉煤灰、外加剂等因素对混凝土强度、工作性能、耐久性等的影响,采取硅粉和粉煤灰双掺技术成功配制某工程C70高性能混凝土,确定了其最佳参数。结果表明,硅粉掺量为17kg/m3,粉煤灰掺量为83kg/m3,高效减水剂(NN)用量为8.6L/m3,普通减水剂(VZ)为3.0L/m3时,混凝土90d抗压强度平均值为79.9MPa,标准差为6.3,离差系数为0.08,保证率为93.4%,同时满足了抗渗、抗冻、抗冲磨及良好的和易性及流动性等一系列高性能要求。 相似文献
9.
马少军 《中国农村水利水电》2004,(11):71-73
结合使用高效减水剂和粉煤灰，不仅克服了单掺粉煤灰混凝土早期强度低和单掺硅粉混凝土早强但后期强度增长缓慢的缺点，可赋予混凝土高强、抗冲磨、抗空蚀等一系列高性能，使混凝土具备良好的和易性和流动性，还能减少单位水泥用量，减轻温控负担。介绍了C70高性能硅粉混凝土在某水电工程中的配制技术及混凝土温控措施。 相似文献
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