Freeze-thaw Testing System For Concrete Hollow Bricks Materials

Our country is located in the north cold area. If frost-resistance of concrete material can not reach to the standard,it need not only expensive maintenance cost but also reconstruction cost for premature damage, and it is likely to cause enormous losses to people’s lives and property. As a important experimental equipment in testing concrete frost resistance, the traditional freeze-thaw Testing System of concrete material has more disadvantages than advantage in real-time data transmission and intelligent control. It still need modulation through artificial way which may lead to the result of low accuracy in long-term experiments. In this paper, by using Labwindows/CVI and single chip microcomputer, it is designed quick freezing and thawing test equipment. It can realize real-time control and acquisition for temperature and liquid level.In this paper, at first it is analyzed the actuality of the freeze-thaw test at home and abroad and freeze-thaw equipment. According to the concrete freeze-thaw test procedures and concrete freeze-thawing equipment of national standards, it is established the subject design scheme. The whole control system is divided into upper machine and lower machine of two parts. In lower machine hardware, the freeze-thaw environment temperature and water level data is detected and acquired by DS180B20 and 154N, and the level data from 154N is processed by AD7705 modulus conversion. As the core of lower machine hardware, ATmega 64 process the freezing and thawing environmental information from sensor, and it also exchange data with upper computer by serial port communication. The design of optoelectronic isolation keep the system stable. The user interface of upper computer is compiled by Labwindows/CVI and it process, preseverat and display the data came from lower machine hardware. In the other parts of the system, the main project is subject test chamber, shield pump according to the test requirement, cold and hot water tank.The ultimate goal of the system is simulating freezing and thawing environment of concrete hollow block accurately. In the experimental process, it can ensure the stability of the test temperature and liquid level. When the temperature and liquid level is abnormal, the system will alarm. In several days of experiment, through the intelligent automation control and real-time record test of temperature information, it can save man power and material resources. System interface is intuitive, concise and convenient for experimental personnel operation and recording data.Through the field test, it is used known anti-freeze grade concrete hollow block material to experiment freezing and thawing test according to the national standard, then it calculated the concrete anti-freeze label.By comparing the existing data,it can establish the concrete freezing and thawing test equipment stability and reliability. The system can also be applied to the existing concrete anti-freeze test. It improve the accuracy in the detection of the concrete building materials, at the same time, indirectly improve the service life of the building and safety. At last, the new system have broad promising applications.