For a long time, the quality of concrete has been evaluated successfully
using ultrasonic pulse velocity method [82]. Ultrasonic
pulse velocity test (UPV) is appropriate to detect flaws in addition
to predicting compressive strength [83]. For suitable selection of
the brick, the evaluation of its quality is very important. For evaluating
the mechanical and durability properties of brick, ASTM
standard procedures involve destructive testing and are time consuming
[83]. Therefore, non-destructive testing like ultrasonic
pulse velocity test can be used in order to reduce the time and cost
of evaluation. In this study, bricks were also evaluated using UPV.
Fig. 26 shows the results of UPV for brick specimens incorporating
RHA and SBA. It was found that UPV decreased for brick specimens
incorporating SBA and RHA. For instance, UPV values reduced from
1643 m/s to 1131 m/s and 1643 m/s to 1098 m/s for 10% SBA and
15% RHA brick specimens, respectively. Generally, pulse velocity
increases with an increase in compressive strength [84]. In all
the tested bricks, UPV results were in consistent with the compressive
strength values. According to previous studies [83], bricks may
be considered durable if UPV is greater than 3500 m/s and nondurable
for UPV less than 1000 m/s. For the value of UPV between
1000 and 3500 m/s, it was recommended to evaluate the durability
of bricks using UPV testing along with ASTM standard procedures
[83]. In this study, the UPV values for all the tested brick specimens
ranged from 1000 to 2000 m/s. Therefore, ASTM C67 standard procedures
was adopted for evaluating the performance of bricks.