双掺大流动性混凝土性能研究

研究了不同粉煤灰掺量对双掺大流动性混凝土性能的影响,并结合高效减水剂及粉煤灰的水化机理及混凝土抗压强度、碳化深度对双掺大流动性混凝土作了一定的性能分析论述,总结出其抗压强度及碳化深度之间存在的关系。     

Deterioration Model and Reliability Analysis on Concrete Material at Stress States

According to the analysis of existing test data, the stress influence coefficient and water-cement ratio influence coefficient in the existing concrete carbonation depth forecasting models are modified and improved. Based on the reliability analysis, the rule of deterioration life is presented. The analysis shows that the rate of carbonation of concrete is accelerated or restricted at the status of tensile or compressive stress, respectively. Especially with the increase of the level of tensile stress, the carbonation rate of concrete will become faster and faster. According to the results of reliability analysis, the relation between probability and reliability of the concrete deterioration is one-to-one corresponsive, meanwhile, the concrete cover thicknesses and stress levels have great influences on the durability life of concrete structures. And with the same reliability, the time of deterioration of concrete decreases with a higher stress levels and a less cover thickness.     

粉煤灰不同掺量对混凝土碳化的影响

对于不同养护龄期、不同粉煤灰掺量及不同水胶比对混凝土碳化的影响进行研究,混凝土的碳化深度与碳化龄期之间的关系可用幂函数D=αTβ进行曲线回归分析,且相关性较好。结果表明,随着粉煤灰掺量及水胶比的增大,混凝土的碳化越严重;混凝土养护龄期越长,混凝土的抗碳化性越好。养护不充分时,高掺量粉煤灰混凝土后期碳化增长速率快;养护较充分时,粉煤灰掺量越小,混凝土早期抗碳化性越好,粉煤灰掺量越大,混凝土后期碳化增长速率越慢。当养护较充分时,水胶比为0.35,粉煤灰掺量为45%时,粉煤灰混凝土抗碳化性较好,能满足工程要求。     

Theoretical Contour Line of Reinforcement Bar of Non uniform Corrosion

Most of the previous studies on corrosion of the steel bar in reinforced concrete structures is based on the assumption that the bar is uniformly corroded. The actual measurement in projects proved that most of the reinforcement bar is in non uniform corrosion state. Based on electrochemical principles of metal corrosion and combined with the real corrosion course of the bar in concrete structures, a theoretical model of the contour line of reinforcement bar due to non uniform corrosion is established, through deducing the speed of corrosion and theoretical corrosion penetration and volume changes due to corrosion of reinforcement in general air at different position and different time. At the same time, the model is verified with the results from relative references and measured data.     

CARBONATION OF THE AUTOCLAVED SILICATE CONCRETE

The carbonation of the concrete in the air is an unavoidable natural process,Itmakes the volume and strength of the concrete change and the alkality reduce,So the structure in-side concrete and the durability both become worse. The carbonation resistance of the autoclaved sil-icate concrete is tested by the means of speeding up the carbonation artificially and also with the ex-periment of the natural carbonation for 6 years. It is very good for recognizing it correctly andspreading.The carbonation of the new concrete material is discussed.     

Carbonation Resistance of High_addition Flyash Concrete

In order to improve carbonation resistance of high_addition flyash concrete,the grinding of flyash and additon of hydrated_lime in flyash concrete have been studied.It is shown that it is possible to improve the carbonation resistance of high_addition flyash concrete by using these methods without reducing its strength.     

Carbonation Depth Prediction of Concrete Structures Based on Inspection Data

There are subjective uncertainty and randomness in concrete carbonation depth forecasting model and the model distribution parameters, which cause significant errors in application to practical engineering. Actual inspection data can not often be used to forecast concrete carbonation depth in the actual project due to its small sample size and lack of sufficient completeness. The weighted value of several model calculations was used to forecast the concrete carbonation depth. By using Bayesian approach, the inspection information and the prior prediction model were incorporated, and the prior model weights and model distribution parameters statistics were updated. It is more accurate to forecast the carbonation depth using the updated model weights and model distribution parameters. The procedure for updating the mechanical model selection and distribution parameter statistics was illustrated with a 10-year-long concrete carbonation test.     

利用碳法滤泥和木薯渣生产有机肥

[目的]进行碳法滤泥和木薯渣堆肥发酵研究,为滤泥和木薯渣快速资源化利用提供参考依据.[方法]以碳法滤泥和木薯渣为原料,设3个处理进行好氧堆肥发酵：木薯渣单独发酵处理（T1,对照）、木薯渣和碳法滤泥干重比1∶1（T2）、木薯渣和碳法滤泥干重比2∶1（T3）,测定堆肥化过程中物料理化性质的变化情况.[结果]在堆肥过程中,T1处理由于初始pH较低,发酵过程受到抑制,在30d堆腐结束时,未达到基本无害状态,种子发芽指数（GI）＜50％,不能满足快速资源化处理的要求.堆腐结束时,T2处理和T3处理在55℃高温上维持时间均超过15d,水分含量均高于35％,pH升高呈弱碱性;导电率（EC）降至安全范围;有机质的降解率分别为52.68％和51.75％;总养分（N＋P2O5＋K2O）分别为：3.12％和3.31％;发酵过程中腐植酸含量呈下降趋势;20 d左右达到完全腐熟状态,GI≥80％;满足无害化指标标准要求.[结论]木薯渣与碳法滤泥干重比为1∶1或2∶1,经过20 d的堆肥发酵后均达到无害化的腐熟标准,有机质降解率高.堆肥产品质量指标基本符合国家有机肥的标准,可用作土壤底肥或是添加N、P、K等营养元素制成高质量的有机肥.     

自密实混合骨料混凝土碳化试验研究

与普通骨料相比,陶粒具有轻质、多孔的特点,降低了混合骨料混凝土的碳化性能。采用加速碳化试验,研究了自密实混合骨料混凝土碳化性能。试验结果表明:2种自密实混合骨料混凝土加速碳化深度随着水胶比增加在增加,其增加值在不同水胶比范围内有明显差异;同水胶比混凝土加速碳化深度由大到小顺序为:自密实轻骨料混凝土和自密实混合骨料混凝土,其中筒压强度高的陶粒配制自密实混合骨料混凝土与自密实混凝土同龄期的加速碳化深度相当;同强度等级混凝土加速碳化深度由大到小顺序为:自密实混凝土、自密实混合骨料混凝土和自密实轻骨料混凝土。