谈钻孔压浆端承桩施工中几个问题

本文主要讨论了钻孔压浆桩施工中桩长的确定,钢筋笼子的安放,水灰比的确定等措施。     

水泥混凝土路面板下脱空的危害

通过对多处水泥混凝土路面板下脱空形态的试验研究 ,获得脱空区的形态分布规律 ,并据此对不同车辆荷载作用下板体内应力变化进行解析求解和使用寿命计算。结果表明 ,水泥混凝土路面板下脱空、超载车辆和重载车辆是造成水泥混凝土路面板早期断裂的重要因素     

旧水泥砼路面沥青加铺层设计研究

对旧水泥混凝土路面进行沥青混凝土罩面考虑的因素,国外罩面厚度设计法,以及反射裂缝的防治措施进行了分析。并针对旧水泥混凝土路面加铺改造,对沥青加铺层改造旧水泥混凝土路面的方法和理论作进一步的研究,试图找到切实可行的改造措施。     

Effect of carbon dioxide-air concentration in the rapid curing process on the properties of cement-bonded particleboard

This study deals with the effects of carbon dioxide (CO₂)-air concentration in the rapid curing method on the properties of cement-bonded particleboard manufactured using conventional cold pressing as the setting method. The hydration of cement was examined using X-ray diffractometry, thermal gravimetry, and scanning electron microscopy. The results are as follows: (1) The properties of CO₂-cured boards improved with increasing CO₂ concentration. When 10% or 20% CO₂ was applied for 10 min of curing time, the properties of the CO₂-cured boards were comparable to those obtained by conventional 2-week curing. (2) The hydration process of cement could be accelerated within several minutes using CO₂ curing, even with a low concentration of 10%–20% CO₂; a reduction in calcium hydroxide was observed followed by rapid formation of calcium carbonate.     

水泥搅拌桩的设计、施工及检测

对水泥搅拌桩在设计、施工、检测等方面作了全面阐述,并且提出了若干注意事项及合理化建议。     

Study on Mechanical Properties of Cement Concrete Pavements

The study of the mechanical properties of cement concrete pavements is the base of the structural design of pavement. The existing mechanical models, such as elastic plate system, layered elastic system and so on, are systematically presented. The limitations and merits of various mechanical models are discussed at the same time. The development process of the solution methods for the study on mechanical properties of cement concrete pavements is also presented. The development trend of the study on pavement mechanical properties is given in the end.     

Study on Titanium Gypsum as Set Retarder for Cement

The chemical composition and form of impurities in titanium gypsum and their effects on properties of cement were introduced when used as set retarder for Portland cement. Experimental results show that the impurities are mainly Fe (OH)_3, FeSO_4 and Al(OH)_3, and they may do little effect to Portland cement. The properties of cement with titanium gypsum are similar to those of Portland cement with natural gypsum,     

A STUDY OF THE HYDRATION AND STRENGTH DEVELOPMENT OF SPONTANEOUS COMBUSTION GANGUE CEMENT

In this paper, by means of X-ray analysis and scanning electron microscope technology, the hydration and strength development of spontaneous gangue cement under the condition of normal atmospheric temperature and steam curing are analysed. This work provides experimental and theoretical basis for the usage of spontaneous combusted gangue cement.     

竹木混合水泥刨花板工艺初步研究

研究了热压法制造竹木混合水泥刨花板工艺并对影响板材性能的因素进行探讨。结果表明:竹刨花水煮预处理后所制备的板材性能较好;本实验范围内,竹木混合水泥刨花板较合适的工艺参数为竹木比1∶3、灰木比4∶1、热压时间1～2min/mm板厚、CaCl2用量为灰重的5%、水灰比0.4。     

Spatial Shifts in Soil Microbial Activity and Degradation of Pasture Cover Caused by Prolonged Exposure to Cement Dust

We ascertained the relationship between the zonal pattern and the pasture vegetation of a volcanic soil polluted with dust from a cement factory after 70 years of operation, with parameters linked to soil microbial activity (soil basal respiration and hydrolases) and physical–chemical properties. Six sampling zones were established at distances of 1, 2, 3, 4, 5 and 6 km away from the cement plant, considering the latter one as the zone where the pastures were unaffected by the cement dust. Plant cover was negatively affected by cement dust, showing a sharp decline with decreasing distance to the cement factory. The values of pH and extractable K were two units and 2·3‐fold higher, respectively, in the sampling zone nearest to the factory, in comparison with those in the unaffected zone. The levels of total Cr, Pb, Ni and Cd were normal and did not vary significantly with distance to the cement factory. Soil respiration and the protease, phosphomonoesterase and β‐glucosidase activities declined significantly with decreasing distance to the cement factory. Urease activity was only decreased in the zone nearest to the factory, in comparison with that in the unaffected zone. The soil respiration and hydrolase activities were correlated positively with soil organic matter and plant cover and negatively with soil pH and extractable K concentration. The prolonged exposure to cement dust has resulted in shifts in the soil microbial function, which follows a spatial pattern related to soil alkalization and the decrease in pasture production. Copyright © 2016 John Wiley & Sons, Ltd.