英语翻译When placement and consolidation cannot be performed pro

英语翻译
When placement and consolidation cannot be performed properly,stiff concretes usually contain large pores and this in turn would result in a substantial decrease in strength [5].Due to the friction between the ingredients of the concrete mixture arises during delivery and hydration of the cement may result in a temperature rise in the truck mixer which this in turn involves a reduction in free water of fresh concrete [6].Concrete stiffens as free water reduces,which this in turn leads to a decrease in workability [7].The practice of retempering is frequently performed to restore the initial slump and keep concrete workable at construction site in order to cope with the need for expediting the casting operations and reducing the consolidation effort.Retempering may be
performed with water only or with a plasticizer or with a combination
of water and plasticizer [8,9].Retempering with water alone
would result in a substantial strength loss since extra water increases
the water to cement ratio of concrete mix [10].However,
retempering with a combination of water and a plasticizer would
be beneficial in terms of the strength loss experienced [11].Consistency
improvement with plasticizers is obviously advantageous
considering the strength gain of concrete; however,it is stated
elsewhere [12–15] that the rheological properties of fresh concrete
may vary depending on the type and amount of plasticizer used.
This could be more complicated for concretes containing fly ash
and silica fume particularly when long delivery times is the issue
[16,17].Ravina [16] in his work indicated that prolonged agitating
of concrete has two technological aspects that should be kept inmind.One is slump loss; the other is the increase in compressive strength up to a certain mixing time.
In this study,it is aimed to clarify the influence of fly ash and silica fume on the slump loss and/or consistency improvement and the strength of concrete subjected to prolonged agitating.Different combinations of concrete mixes were tested as compared to the usual practice of mixes to monitor the variation in relation
with slump loss depending on agitation duration.To do this,mineral
additives at different ratio were added to the mix instead of
replacement as opposed to the common practice.Concrete mixes of C25/30 class having approximately 200 ± 10 mm initial slump with and without mineral additives of
fly ash and silica fume were produced.At the end of each agitating
period,150 mm cubes from each mix were prepared for compressive
strength measurements.Concretes were also produced to measure the standard 28-day compressive strength.The results obtained were compared with those of without fly ash and silica fume.2.Experimental program and procedure

当安置和巩固不能正确执行,僵硬的混凝土通常含有大量孔隙,这反过来会导致在力量[5]大幅下降.由于混凝土混合物之间的摩擦产生的成分,并在分娩过程中的水泥水化可能会导致在搅拌车而这又涉及到新拌混凝土[6]免费的水还原温度上升.作为自由水混凝土变硬减少,而这反过来又导致了减少工作性[7].该retempering实践常常是为了恢复和保持初始坍落度混凝土可行的施工现场,以应付对加快铸造业务和降低整合工作的需要. Retempering可能
水只执行或增塑剂或组合
水和增塑剂[8,9].单独与水Retempering
将导致大量增加,因为多余的水强度损失
水对水泥混凝土配合比[10]比.然而,
retempering与水结合,增塑剂会
在损失方面的实力有益经验[11].一致性
与增塑剂的改善是明显的优势
考虑混凝土的强度增益,但它说明
文献[12-15]的新拌混凝土的流变性能
可能会因不同的类型和增塑剂的使用量而定.
这可能是更复杂的含粉煤灰混凝土
硅粉和交货时间长,尤其是当这个问题
[16,17].拉维纳[16]在他的工作表明,长期搅拌
具体有两个应保持inmind技术方面.一个是坍落度损失,另一个是抗压强度增幅高达一一定的混合时间.
在这项研究中,它的目的是澄清对粉煤灰的影响和坍落度损失和/或一致性的改善和遭受长时间搅拌混凝土强度硅粉.混凝土混合物的不同组合进行比较惯例的测试混音监察关系变化
躁动与坍落度损失的时间而定.要做到这一点,矿产
在不同比例的添加剂被添加到组合,而不是
更换而不是常见的做法.混凝土混合物的C25/30类有大约200 ± 10毫米,无矿物添加剂初始坍落度
粉煤灰和硅粉的生产.激荡在每个月底
期间,150毫米每个组合立方体抗压强度准备
强度测量.混凝土也产生了衡量标准的28天抗压强度.所获得的结果进行比较,那些没有粉煤灰和硅粉的. 2.实验方案和程序