n	the erosion time
${\mathsf{\phi }}_{\mathrm{i}}$	the rate of mass change of the concrete specimen
$m_n$	the mass of the specimen after the erosion time n
$m_0$	the initial mass
v	the longitudinal wave velocity
l	the path length
t	the average ultrasound time
$t_1$	the ultrasonic time value of each pair of measuring points
$t_2$	the ultrasonic time value of each pair of measuring points
$t_3$	the ultrasonic time value of each pair of measuring points
$t_4$	the ultrasonic time value of each pair of measuring points
$t_5$	the ultrasonic time value of each pair of measuring points
$E_r(n)$	the relative dynamic elastic modulus
$E_n$	the dynamic elastic modulus after the erosion time n
$E_0$	the initial dynamic elastic modulus
$v_n$	the longitudinal wave velocity of the concrete specimen after the erosion time n
$v_0$	the initial longitudinal wave velocity
$k_c$	the corrosion resistance coefficient of compressive strength of the concrete specimen
$f_{cn}$	the compressive strength after the erosion time n
$f_{c0}$	the uncorroded compressive strength
$k_t$	the corrosion resistance coefficient of splitting tensile strength of the concrete specimen
$f_{tn}$	the split tensile strength after the erosion time n
$f_{t0}$	the split tensile strength without sulfate attack
D 1	the sulfate erosion damage variables corresponding to the corrosion resistance coefficient of compressive strength
D 2	the sulfate erosion damage variables corresponding to the corrosion resistance coefficient of splitting tensile strength
D 3	the sulfate erosion damage variables corresponding to the longitudinal wave velocity
$\psi$	fly ash content