Concrete is the age strength nondestructive determination early
Technical field
The present invention is an a kind of concrete age strength lossless detection method early, can on-the-spotly detect age strength morning after the concrete depositing, and can monitor in real time its gain in strength growth course, belongs to construction engineering technical field.
Background technology
Concrete is one of topmost in the current construction work, that consumption is maximum building materials, and its quality is directly connected to the safety of building structure.The concrete Non-Destructive Testing is one of main means of present xoncrete structure safety assessment and quality control on construction, and its range of application mainly concentrates on the intensity of structure and two aspects of detection of inherent vice.The method of widespread usage has the integrated application of rebound method, ultrasonic method, core drilling method, dial-out method and above-mentioned several method at present.China has formulated the technical regulation of corresponding concrete Non-Destructive Testing.Detect concrete crushing strength technical regulation (JGJ/T23-200) 1 as rebound method); The ultrasonic rebound overall approach detects concrete strength technical regulation (CECS02:88); Core drilling method detects concrete strength technical regulation (CECS21:2000); Back dress dial-out method detects concrete strength technical regulation (CECS69:94) etc.But aspect the monitoring of early age strength of concrete growth, generally be at present according to its early strength of the guestimate age of concrete.Once adopted the evolution of dial-out method and gunning (winder prole) monitored concrete intensity abroad, but the former belongs to damaged detection, coordination detects continuously, and the latter is bigger because of the coarse aggregate influence, and poor effect is not used widely.And rebound method only limits to grow the length of time concrete strength Non-Destructive Testing of (>7 days).At the concrete depositing initial stage, gain in strength is very fast, corresponding therewith numerous construction technologies (the member form removal, go out maintenance pond, tension of prestressed tendon and open put, the construction work load is to the requirement of concrete strength, and the continuous pouring of mass concrete etc.) all need the growth and the growth course of early age strength of concrete are carried out continuous monitoring, so that construction quality is advanced to imitate control.
Summary of the invention
The objective of the invention is to overcome above-mentioned lossless detection method and can not detect the concrete deficiency of age strength early, a kind of on-the-spot concrete lossless detection method-fixed wave velocity method of age strength early that detects is provided.This method can also fix a point to the growth growth course of early age strength of concrete, continuously, monitoring in real time
The present invention solves the technical scheme that its technical matters takes: in concrete sample or structure, in advance vertical test specimen or body structure surface embedding with test specimen or the isometric reinforcing bar measuring staff of structural thickness, behind the deposit concrete at test specimen or body structure surface, adopt general Ultrasound Instrument or high-speed data acquisition instrument, by end survey or method (the termination exposure situation of surveying part on reinforcing bar is decided), measure the fixed velocity of wave of reinforcing bar-concrete system to surveying.According to the correlativity (promptly surveying strong curve) of fixed velocity of wave and concrete strength, infer concrete morning of age strength and the growth situation of change of concrete strength.
Fixed velocity of wave is the velocity of wave when exciting stress wave to pass through reinforcing bar-concrete system.Its numerical value neither concrete longitudinal wave velocity neither the longitudinal wave velocity of reinforcing bar.But between reinforcing bar and concrete velocity of wave, be the velocity of wave of a kind of boundary wave that the negative exponent rule changes with the gain in strength age of concrete, its mathematic(al) representation is:
c
c=c
0+ ae
-f/b, in the formula, c
cBe fixed velocity of wave (m/s) that f is concrete compressive strength (Mp), c
0The relevant constant (m/s) of velocity of wave when reaching final strength with concrete; A is that coefficient, the b relevant with the velocity of wave of concrete and reinforcing bar is and concrete material and the relevant coefficient of match ratio, can be by measuring.The variation of fixed velocity of wave comes from different age concretes to the bonding of reinforcing bar constraint (being cohesive strength) effect, is the concrete reflection of the matter of age strength early, with concrete early age strength the correlativity of apparent chopsticks is arranged.As the physical quantity of concrete age strength Non-Destructive Testing early, have measure convenient and easy, can be continuously, the characteristics of monitoring in real time.
The invention has the beneficial effects as follows: can on-the-spot quickly and easily Non-Destructive Testing concrete morning of age strength, and can monitor in real time the growth growth course of concrete strength.
Description of drawings
Fig. 1 is that fixed velocity of wave is to surveying the method system chart.
Fig. 2 is that fixed velocity of wave end is surveyed the method system chart.
1. reinforcing bar measuring staffs among the figure, 2. concrete sample or structure, 3. auto-excitation type acceleration transducer, 4. acceleration transducer, 5. charge amplifier, 6. high-speed data acquisition instrument, 7. computing machine, 8. Ultrasound Instrument.
Embodiment
The present invention is further described below in conjunction with drawings and Examples.
Embodiment 1: among Fig. 1 to the fixed wave velocity testing of survey formula system, be applicable to the situation of reinforcing bar measuring staff two ends exposure.Auto-excitation type acceleration transducer (3) and acceleration transducer (4) are placed the two ends of the reinforcing bar measuring staff (1) of imbedding the deposit concrete member, constitute test macro with charge amplifier (5) and high-speed data acquisition instrument (6).Computing machine (7) is used for the data processing of above-mentioned test macro.Spur the bar that excites of auto-excitation type acceleration transducer (3), give (1) shock-excitation signal of reinforcing bar measuring staff, the consequent stress wave that excites is propagated in reinforcing bar-concrete system, acceleration transducer (3) and (4) are gathered the stress wave signal that excites the stress wave Mintrop wave and arrive at the reinforcing bar measuring staff other end simultaneously, through the time interval that system amplifies and the record stress wave is propagated in reinforcing bar measuring staff-concrete system, and by the fixed velocity of wave of COMPUTER CALCULATION.The strong curve of the concrete survey of same proportioning that contrast is measured in advance draws the concrete at that time age strength of test.
Embodiment 2: the end among Fig. 2 is surveyed the fixed wave velocity testing of formula system, is applicable to that reinforcing bar measuring staff one brings out the situation of dew.As laminated pouring of reinforced concrete anchoring piece and mass concrete etc.Install auto-excitation type acceleration transducer (3) at the exposure end of reinforcing bar measuring staff (1), constitute test macro with Ultrasound Instrument (8) and computing machine (7).Spur the bar that excites of auto-excitation type acceleration transducer (3), after giving reinforcing bar-concrete system one shock-excitation signal, auto-excitation type acceleration transducer (3) writes down the stress wave signal that excites the stress wave Mintrop wave and reflect via the reinforcing bar measuring staff other end simultaneously, as calculated after machine (7) Filtering Processing, the time interval that identification excites stress wave to come and go in reinforcing bar measuring staff (1), and calculate fixed velocity of wave.Draw the concrete at that time age strength of test with embodiment 1 same method.
Test macro in above-mentioned two kinds of methods can exchange, can be at same measuring point, and certain hour at interval regularly, METHOD FOR CONTINUOUS DETERMINATION concrete morning of age strength, realizes that concrete strength increases the real-time monitoring of growth course.
The concrete of various labels is the strong curve of survey of the fixed wave velocity method Non-Destructive Testing of age strength early, the method of available embodiment 1, design by the proportioning of JGJ55-81 " design of common concrete proportioning regulation " in the laboratory in advance, under GBJ107-87 " concrete strength check and evaluation criteria " defined terms, measure.