CMA

10 amplifier and the drive terminal. The oscillator has the frequency of 500 to 10,000 Hz and can be adjusted with the error of ± 2%. The pickup circuit consists of the pickup, the amplifier and the indicator. The pickup produces the voltage proportional to the amplitude, vibration velocity or acceleration of the specimen. The support stand is configured so as not to restrain the vibration of the specimen. Figure 1 The outline of the device used to measure elastic modulus of concrete specimens The dynamic elastic modulus was calculated by measuring the first-order resonance vibration of the deflection vibration according to JIS A 1127 (Methods of test for dynamic modulus of elasticity, rigidity and Poisson’s ratio of concrete by resonance vibration) 5.2 b method by using this device. The dynamic elastic modulus was calculated by below equation (1). E d : Dynamic elastic modulus (N/mm2) L : Length of specimen (mm) Water Absorption Test Method Permeability to water of reference and modified concrete specimens was assessed according to JIS A 6909: 2014 “Water Permeability Test B Method”. A funnel with the diameter of 75 mm is attached to the cylindrical concrete specimens (φ100 x 200mm) by using silicon sealant. The pipette which enables measurement of absorbed water is connected to the funnel with a rubber tube. Water is then poured in the device such as the height is about 250 mm high from the surface of the concrete specimens. Volume of water absorbed by the concrete specimens is measured after 24 hours contact time with water. The experimental set up to measure water permeability is illustrated in Photo-1. Photo-1. Measurement status Compressive Strength of Concrete Test Method The compressive strength of concrete was evaluated according to JIS A 1108. Specimen made according to JIS A 1132, shape of specimen was φ100mm × L200mm, and compressive strength was measured after 7 days water immersion curing. Elastic modulus of concrete. Test method The dynamic elastic modulus of the concrete is the elastic coefficient obtained from testing the wave characteristic (vibration period and propagation velocity) and is used as a measure of the changes in concrete specimens over time. The outline of the measuring device is shown in Figure 1. The measuring device consists of the drive circuit and the pickup circuit. The drive circuit consists of the oscillator with variable frequency, the Amplifier Amplifier Indicator Oscillator Oscilloscope Drive Terminal Pickup Deflection Vibration Specimen L Support Stand 0.5L 0.224L Pickup Drive terminal Support Stand