When measuring, divide the total length of the crack into four equal parts, the central point and the two ends, and the central point and the third point in the middle. To measure the vertical width in the direction of the crack, use a special microscope with a scale, place the scale perpendicular to the crack, measure the width of the crack, record the reading and mark it on the graph.
You can also use the crack card to estimate the crack width through a magnifying glass, but this method has a large error. The length of the crack can be measured with a steel ruler, and there should be a mark at the end of the crack, and the year, month and day should be marked to observe the development of the crack.
When measuring the length and width of cracks, the thickness of the protective layer must be confirmed at the same time. When the concrete thickness of the protective layer is not suitable for chiseling, the steel detector can be used to find out its thickness.
03 Determination of crack depth
Ultrasonic method is usually used to detect the depth of cracks in terrazzo floor tiles, and the depth of cracks can be calculated from the relationship between the measured acoustic time and the probe.
Ultrasonic testing of crack depth should be carried out at a position avoiding steel bars, and it is only suitable for some stressed cracks, because the concrete on both sides of such cracks is generally completely separated. Ultrasonic testing is less accurate if the concrete on both sides is not completely separated.
For components whose cracks are not deep and whose direction is roughly in a straight line, the direct coring method can be used for detection.
The method of prefabricated terrazzo is to drill the concrete core sample along the depth direction at the position where there is a crack, so that the crack depth can be directly measured on the side of the core sample, and the disadvantage is that there is a certain damage to the component.
04 裂縫發(fā)展情況觀測(cè)
對(duì)于活動(dòng)裂縫，應(yīng)進(jìn)行定期觀測(cè)，專用儀器有接觸式引伸儀、振弦式應(yīng)變儀等，最簡(jiǎn)單的辦法是騎縫涂抹石膏餅觀察。
在典型裂縫位置處抹50mm左右見(jiàn)方的石膏餅，觀察石膏餅是否沿原裂縫開裂，就可確定裂縫是否在繼續(xù)發(fā)展。石膏餅開裂寬度大，說(shuō)明裂縫增長(zhǎng)也大，將裂縫的變化情況亦記于圖上。通過(guò)以上觀測(cè)繪制形成的裂縫圖，即可作為裂縫分析的依據(jù)。
5、裂縫修復(fù)措施
裂縫處理的原則：
1）首先應(yīng)能保證裂縫處理后結(jié)構(gòu)原有的承載能力、整體性以及防水、抗?jié)B性能；
2）其次要考慮溫度、收縮應(yīng)力較長(zhǎng)時(shí)間的影響，以免處理后再出現(xiàn)新的裂縫；
3）再次應(yīng)防止進(jìn)一步的人為損傷結(jié)構(gòu)和構(gòu)件，盡量避免大動(dòng)大補(bǔ)，并盡可能保持原結(jié)構(gòu)的外觀。
