CN101551380A

CN101551380A - Method for estimating concrete strength of thin-walled structure by using small core sample strength

Info

Publication number: CN101551380A
Application number: CNA2009100265497A
Authority: CN
Inventors: 刘辉; 刘梦溪; 韩成标; 周国庆; 解恒参
Original assignee: XUZHOU INSTITUTE OF ARCHITECTURAL TECHNOLOGY
Current assignee: XUZHOU INSTITUTE OF ARCHITECTURAL TECHNOLOGY
Priority date: 2009-05-01
Filing date: 2009-05-01
Publication date: 2009-10-07

Abstract

The invention discloses a method for estimating the concrete strength of the thin-walled structure by using the small core sample strength, which belongs to the concrete strength detection of construction projects. The main technical proposal is as follows: a core sample with the diameter of 48mm is drilled from the concrete entity of the thin-walled structure through the cutting and polishing, the compressive strength test is conducted by using an universal material testing machine to obtain a concrete compressive strength value of the small core sample, and the concrete strength of the thin-walled structure is deduced by a correction factor formula. The invention has the advantages of small error and high accuracy, can be applied to the quality control in the construction projects under construction, and the assessment and identification of justice in the existing building and the construction after the disaster.

Description

Method with small core sample estimating concrete strength of thin-walled structure intensity

Technical field

The invention belongs to the construction work concrete strength and detect, be specifically related to a kind of method with small core sample estimating concrete strength of thin-walled structure intensity.

Background technology

Concrete strength is the basic foundation of evaluation construction engineering quality.Under normal circumstances, xoncrete structure should be by the requirement of " reinforced concrete construction and acceptance specification ", make cube standard curing test block and carry out the evaluation and the examination of concrete strength, but when running into some special circumstances (to the test result of test block compressive strength when with suspicion, because of material, construction or maintenance are bad and when the concrete quality problem takes place, concrete suffers freeze injury, fire, in the time of need detecting in the building structure used for many years or the buildings concrete strength during chemical erosion or other infringement), will directly carry out quality testing and evaluation to member itself, wherein a kind of half lossless detection method---core drilling method (drill through concrete core sample and detect its intensity) is generally believed it is a kind of directly perceived, method reliable and that accurately the intensity of concrete component is evaluated.

The method with core strength of structural concrete intensity of " core drilling method detects concrete strength technical regulation " regulation, its main points are that the requirement core diameter is not less than 70mm.But in the practice of using unbearable method mensuration concrete strength, often following problems may be encountered: along with proportion high-rise, high-rise building is increasing.People are more and more higher to the requirement of the degree of safety of structure and antidetonation, make that all the reinforced component rate is increasing, and bar spacing is more and more littler.As the spacing of longitudinal stress reinforcing bar in beams of concrete, the post and encrypted area stirrup have below 70mm.According to " core drilling method detect concrete strength technical regulation ", in core, be difficult to avoid not getting reinforcing bar, and reinforcing bar is a still unsolved challenge to the influence of core compressive strength, therefore, has greatly influenced core drilling method accuracy of detection and confidence level; In addition, in detection, send out the concrete thickness of slab existing less than 70mm, and the core that " core drilling method detect concrete strength technical regulation " adopts diameter to take out less than the drill bit of 70mm thickness less than the thin-wall member of 70mm is evaluated its concrete strength and is not done regulation, causes in the actual mass testing the difficulty of thickness less than the thin-wall member strength assessment of 70mm.

Summary of the invention

The present invention is directed to the deficiency of " core drilling method detects concrete strength technical regulation ", a kind of method with 48mm small core sample estimating concrete strength of thin-walled structure intensity is provided; This method is specially adapted to Jiangsu Province's Xuzhou Area, drills through diameter 48mm, and 1: 1 small core sample of ratio of height to diameter is inferred the method for thin-wall construction concrete strength.

Concrete technical scheme of the present invention is as follows: a kind of method with core estimating concrete strength of thin-walled structure intensity mainly comprises following step:

1) on the thin-wall construction concrete, drills through earlier diameter 48mm core;

2) core is cut, polishes;

3) carry out compressive strength test with universal testing machine, draw the concrete crushing strength value of core test specimen;

4) utilize correction factors formula to infer out the thin-wall construction concrete strength according to the concrete crushing strength value of core test specimen.Inferring the thin-wall construction concrete strength calculates as follows:

f _cu，e＝1.28f _cu，cor

f _{Cu, cor}---the concrete crushing strength value (MPa) of small core sample test specimen

f _{Cu, e}---structural concrete compressive strength presumed value (MPa).

Advantage of the present invention: 1., compare, significantly reduce because of detecting repairing, the reinforcing expense that damage structure or member cause with big core core drilling method because the 48mm core diameter is less.2. the 48mm core utilizes pre-determined correction factors formula to be converted into the concrete standard compression strength value, unite with concrete works design strength and delivery receiving acceptance intensity, promptly all be corresponding 150 * 150 * 150 cube standard compressive strength, thereby have good comparability, be convenient to the quality inspection utilization.3. use that establish concrete strength error of the present invention is little, precision is high, can estimate concrete engineering quality objectively, stop hidden dangers in project.

Embodiment

Further specify method of the present invention and effect below in conjunction with embodiment.

Embodiment

Adopt this method on engineering structure every batch drill through Φ 48mm * 48mm core test specimen and carry out compression test for 3 groups.In different building sites, selected 4 strength grades altogether, 16 structure positions drill through ratio of height to diameter and are 1: 1 48 groups of Φ 48mm cores.Test result sees Table 1.

Table 1 engineering structure concrete is got the core intensity table of comparisons

Claims

1, a kind of method with small core sample estimating concrete strength of thin-walled structure intensity, it is characterized in that: it may further comprise the steps: the core that drills through diameter 48mm on the thin-wall construction concrete solid, by cutting, polishing, carry out compressive strength test with universal testing machine then, draw the concrete crushing strength value of small core sample test specimen, utilize correction factors formula to infer out the thin-wall construction concrete strength again; Concrete steps are:

1) elder generation's core boring sampling on the thin-wall construction concrete solid;

2) core is cut, polishes;

3) carry out compressive strength test with universal testing machine, draw the concrete crushing strength value of small core sample test specimen;

4) utilize correction factors formula to infer out the thin-wall construction concrete strength according to the concrete crushing strength value of core test specimen;

Inferring the thin-wall construction concrete strength calculates as follows:

f _cu，e＝1.28 _fcu，cor

In the formula: f _{Cu, cor}---the concrete crushing strength value (MPa) of small core sample test specimen

f _{Cu, e}---structural concrete compressive strength presumed value (MPa).

2, the method with small core sample estimating concrete strength of thin-walled structure intensity according to claim 1, it is characterized in that: adopt adamas or the man-made diamond thin drilling bit of internal diameter 48mm during core boring sampling, bit matrix must not have macroscopic crack, scarce limit, Shao Jiao, inclination and hydraucone distortion.

3, the method with small core sample estimating concrete strength of thin-walled structure intensity according to claim 1, it is characterized in that: core is cut, polishes, and being processed into ratio of height to diameter is 1: 1.

4, the method with small core sample estimating concrete strength of thin-walled structure intensity according to claim 1, it is characterized in that: the concrete coarse aggregate of thin-wall construction is 5～20mm, intensity is at 15～60Mpa, natural curing.