《混凝土》2015年第4期 转载须注明出处违者必究
【摘要】 通过发现运用回弹法和钻芯法这两种方法检测工程结构混凝土强度时差生的差异,分析了该差异产生的原因,提出了面对差异的应对措施。
0 引言
近几年,预拌混凝土厂家对运用回弹法检测推定工程结构混凝土强度的意见越来越大,认为运用回弹法检测推定工程结构混凝土强度是偏低的。为了弄清楚,运用回弹法检测推定工程结构混凝土强度是否是偏低的,为什么是偏低的,在2014年沈阳市建设工程质量检测中心对多个工程结构混凝土进行了回弹法和钻芯法的比较检测验证,比较验证检测的工程结构的混凝土强度等级为C25、C30、C35、C40、C45、C50。为了保证检测对比验证数据的可靠性,采用了“云回弹仪”,回弹数据即时转到检测中心数据库。比较验证的结果证明:对同一工程结构的混凝土,运用回弹法检测推定工程结构混凝土强度大幅度低于运用钻芯法检测推定工程结构混凝土强度。本文仅以C30的检测验证数据为例,展开了工程结构混凝土因两种检测方法不同产生差异的讨论,其中包括差异现象、差异原因和面对差异的应对措施。
1 差异现象
在2014年多半年的时间内,沈阳市建设工程质量检测中心对多个工程结构多个强度等级的混凝土强度进行了回弹法和钻芯法的同测区的比较检测验证,检测验证的结果详见以下表一针对多个工程结构C30混凝土同测区进行回弹法和钻芯法的比较检测验证数据:
表1 同一测区回弹法与钻芯法检测推定的混凝土强度值比较
序号
|
设计强度等级
|
回弹法强度值
|
回弹法占设计强度百分比
|
钻芯法强度值
|
钻芯法占设计强度百分比
|
芯样强度/回弹强度
|
回弹强度/芯样强度
|
1
|
C30
|
21.3
|
71%
|
40.5
|
135%
|
1.90
|
53%
|
2
|
C30
|
19.6
|
65%
|
50.8
|
169%
|
2.59
|
39%
|
3
|
C30
|
17.8
|
59%
|
41.7
|
139%
|
2.34
|
43%
|
4
|
C30
|
17.4
|
58%
|
40.1
|
134%
|
2.30
|
43%
|
5
|
C30
|
18.8
|
63%
|
38.3
|
128%
|
2.04
|
49%
|
6
|
C30
|
18.4
|
61%
|
32.3
|
108%
|
1.76
|
57%
|
7
|
C30
|
18.1
|
60%
|
36.4
|
121%
|
2.01
|
50%
|
8
|
C30
|
16.9
|
56%
|
34.4
|
115%
|
2.04
|
49%
|
9
|
C30
|
17.8
|
59%
|
35.3
|
118%
|
1.98
|
50%
|
10
|
C30
|
28.2
|
94%
|
50.6
|
169%
|
1.79
|
56%
|
11
|
C30
|
28.6
|
95%
|
53.7
|
179%
|
1.88
|
53%
|
12
|
C30
|
30.2
|
101%
|
52.4
|
175%
|
1.74
|
58%
|
13
|
C30
|
18.8
|
63%
|
49.4
|
165%
|
2.63
|
38%
|
14
|
C30
|
21
|
70%
|
36
|
120%
|
1.71
|
58%
|
15
|
C30
|
18.8
|
63%
|
39.8
|
133%
|
2.12
|
47%
|
16
|
C30
|
20
|
67%
|
41.4
|
138%
|
2.07
|
48%
|
17
|
C30
|
20.7
|
69%
|
43.3
|
144%
|
2.09
|
48%
|
18
|
C30
|
19.6
|
65%
|
44.2
|
147%
|
2.26
|
44%
|
19
|
C30
|
22
|
73%
|
38.7
|
129%
|
1.76
|
57%
|
20
|
C30
|
21.4
|
71%
|
31.9
|
106%
|
1.49
|
67%
|
21
|
C30
|
20.8
|
69%
|
32.8
|
109%
|
1.58
|
63%
|
22
|
C30
|
19.8
|
66%
|
38.3
|
128%
|
1.93
|
52%
|
23
|
C30
|
20
|
67%
|
43.3
|
144%
|
2.17
|
46%
|
24
|
C30
|
20.4
|
68%
|
49.2
|
164%
|
2.41
|
41%
|
25
|
C30
|
20.8
|
69%
|
42.8
|
143%
|
2.06
|
49%
|
26
|
C30
|
21.2
|
71%
|
46.7
|
156%
|
2.20
|
45%
|
27
|
C30
|
18.9
|
63%
|
42.6
|
142%
|
2.25
|
44%
|
28
|
C30
|
21.1
|
70%
|
40.3
|
134%
|
1.91
|
52%
|
29
|
C30
|
20.1
|
67%
|
37.8
|
126%
|
1.88
|
53%
|
30
|
C30
|
20.4
|
68%
|
33.2
|
111%
|
1.63
|
61%
|
31
|
C30
|
27.1
|
90%
|
41
|
137%
|
1.51
|
66%
|
32
|
C30
|
21.9
|
73%
|
45.1
|
150%
|
2.06
|
49%
|
33
|
C30
|
22.3
|
74%
|
45.8
|
153%
|
2.05
|
49%
|
34
|
C30
|
24.8
|
83%
|
42.6
|
142%
|
1.72
|
58%
|
35
|
C30
|
20
|
67%
|
41.7
|
139%
|
2.09
|
48%
|
36
|
C30
|
18.2
|
61%
|
38.7
|
129%
|
2.13
|
47%
|
37
|
C30
|
19.5
|
65%
|
37.1
|
124%
|
1.90
|
53%
|
38
|
C30
|
20.8
|
69%
|
32.3
|
108%
|
1.55
|
64%
|
39
|
C30
|
24.5
|
82%
|
37.8
|
126%
|
1.54
|
65%
|
40
|
C30
|
15.2
|
51%
|
27.8
|
93%
|
1.83
|
55%
|
41
|
C30
|
22.8
|
76%
|
26.9
|
90%
|
1.18
|
85%
|
42
|
C30
|
24
|
80%
|
37.6
|
125%
|
1.57
|
64%
|
43
|
C30
|
19.6
|
65%
|
26.9
|
90%
|
1.37
|
73%
|
44
|
C30
|
22.8
|
76%
|
41.2
|
137%
|
1.81
|
55%
|
45
|
C30
|
21.2
|
71%
|
36
|
120%
|
1.70
|
59%
|
46
|
C30
|
23.9
|
80%
|
29.1
|
97%
|
1.22
|
82%
|
47
|
C30
|
25.5
|
85%
|
40.1
|
134%
|
1.57
|
64%
|
48
|
C30
|
20.9
|
70%
|
42.1
|
140%
|
2.01
|
50%
|
49
|
C30
|
22.9
|
76%
|
33
|
110%
|
1.44
|
69%
|
50
|
C30
|
18.6
|
62%
|
30.7
|
102%
|
1.65
|
61%
|
51
|
C30
|
19.7
|
66%
|
35.5
|
118%
|
1.80
|
55%
|
52
|
C30
|
24.1
|
80%
|
32.8
|
109%
|
1.36
|
73%
|
53
|
C30
|
24.2
|
81%
|
32.8
|
109%
|
1.36
|
74%
|
54
|
C30
|
24.6
|
82%
|
41
|
137%
|
1.67
|
60%
|
55
|
C30
|
25
|
83%
|
42.6
|
142%
|
1.70
|
59%
|
56
|
C30
|
27.8
|
93%
|
32.1
|
107%
|
1.15
|
87%
|
57
|
C30
|
21
|
70%
|
32.1
|
107%
|
1.53
|
65%
|
58
|
C30
|
19.9
|
66%
|
37.8
|
126%
|
1.90
|
53%
|
59
|
C30
|
24.5
|
82%
|
34.2
|
114%
|
1.40
|
72%
|
60
|
C30
|
21.2
|
71%
|
34.6
|
115%
|
1.63
|
61%
|
61
|
C30
|
15.9
|
53%
|
27.8
|
93%
|
1.75
|
57%
|
62
|
C30
|
17.6
|
59%
|
33.2
|
111%
|
1.89
|
53%
|
63
|
C30
|
17.8
|
59%
|
48.5
|
162%
|
2.72
|
37%
|
通过观察表1的数据,我们可以清楚地看到,在工程结构C30混凝土同一测区进行回弹法和钻芯法的检测数据里,回弹强度/芯样强度的均值为55%,最小值为37%,最大值为87%,小于60%的占78%,这对同一工程结构混凝土强度的推定产生了很大的差异。为了直观地看出这一差异,可以观察图1同一测区回弹法与钻芯法检测推定的混凝土强度值分布。
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