问题 问答题 简答题

人体积混凝土施工中如何控制温度?

答案

参考答案:

(1)原材料

1)优先采用水化热低的水泥,如大坝水泥、矿渣硅酸盐水泥等。

2)在保证混凝土强度等级的前提下,使用适当的缓凝减水剂,减少水泥用量、降低水灰比,以减少水化热。

3)冷却骨料,特别是冷却粗骨料较冷却细骨料容易一些,具体方法是石子浇水。

(2)施工工艺

1)控制浇筑层厚度和进度,以利散热。

2)控制浇筑温度,如在浇筑混凝土时投入适量毛石、蛮石(粒径达150mm的大骨料),以吸收热量,并节约部分混凝土材料,但在这种混凝土中,“毛石块”不应大于总体积的20%~30%:

3)预埋冷却水管,用循环水降低混凝土温度,进行人工导热。循环水是通过管道系统泵入的,以井水为最好:

4)在拌合水中加入部分冰块或全部用冰水也是可行的。因此,浇筑温度低于10℃是容易达到的,进一步降至10℃以下则较困难。拌合物需水量通常随温度降低而减少,故冷却混凝土配合比是有利的。

5)设测温装置,加强观测,并作好记录。

阅读理解

Play is the basic business of childhood, and in recent years more and more research has shown the great importance of play in the development of a human being. From earliest  infancy (婴儿), every child needs opportunity and the right material for play, and the main tools of play are toys. The main function of toys is to suggest, encourage and assist play. To succeed in this, they must be good toys, which children will play with often and will come back to again and again. Therefore, it is important to choose suitable toys for different stages of a child’s development.

In recent years research on infant development has shown that the standard a child is likely to reach, within the range of his inherited(遗传的) abilities, is largely determined in the first three years of his life. So a baby's ability to benefit from the right play materials should not be underestimated. A baby who is encouraged, talked to and shown things and played with, has the best chance of growing up successfully.

The next stage, from three to five years old, curiosity knows no bounds. Every type of suitable toy should be made available to the child, for trying out, experimenting and learning, for discovering his own particular ability. Bricks and jigsaws and construction toys; painting, scribbling(乱涂) and making things; sand and water play; toys for imaginative and pretending play; the first social games for learning to play and get on with others.

By the third stage of play development—from five to seven or eight years old— the child is at school. But for a few more years play is still the best way of learning, at home or at school. It is easier to see which type of toys the child most enjoys.

Until the age of seven or eight, play and work mean much the same to a child. But once reading has been mastered, then books and school become the main source of learning. Toys are still interesting and valuable, which lead up to new hobbies, but their significance has changed —to a child of nine or ten years old, toys and games mean, as to adults, relaxation and fun.

小题1:The writer wants us to understand that a child_______.

A.cannot grow up without toys

B.matures(使成熟) through play

C.uses toys as friends

D.has to be taught how to play小题2:According to the passage, the abilities a child has inherited from his parents ________.

A.determine his character

B.will not change after the age of three

C.partly determine the standard he is likely to reach

D.to a large extent determine the choice of toys小题3:The passage tells us that children are the most curious when they are about______.

A.two years old

B.one year old

C.six years old

D.four years old小题4:The article is about_______.

A.the importance of play

B.the importance of books

C.the relationship between play and work

D.children’s speech development

单项选择题