I WAS ENTERING A FREEWAY ON AN ENTRANCE. THE CARS IN FRONT ME BEGAN TO SLOW DOWN. I WAS GOING ABOUT 45 MPH. I APPLY BRAKES AND I DIDN'T FEEL A SLOW DOWN. I REACTED BY THEN SLAMMING THE BRAKES AND I WANT SLOWING DOWN. I SWERVED INTO THE SHOULDER HIT THE CONCRETE WALL, THEN HIT ANOTHER CAR FROM THE SIDE THAT WAS ABOUT 4 CARS DOWN AND THEN HIT THE CONCRETE WALL AGAIN. THE ENTIRE TIME I HAD THE BRAKES PRESSED COMPLETELY DOWN. I DID STOP AND I HAD THE BRAKES FLOORED. THE PRESSURE I'M USED TO FEELING WAS NO THERE. NO ONE WAS SERIOUSLY HURT. I TRAVELLED PASSED 6 CARS AND HIT 1. I HAD PLENTY OF TIME AND DISTANCE TO BREAK, I COULDN'T STOP. THERE WERE NO WARNINGS MY BRAKES WERE A PROBLEMS. I HAD JUST REPLACED ALL 4 BRAKES PADS JUDY 2018 AND DID NOT HAVE ANY ISSUES. THE FREEWAY RAMP I ENTERED HAD CONSTRUCTION SO I WAS ENCLOSED AND HAD NO OPTION BUT THE CONCRETE WALL AND THE RAMP WAS ENDING SINCE IT MERGED INTO THE HIGHWAY.