USING 2 IN. CUBICAL SPECIMENS, BIAXIAL COMPRESSION-COMPRESSION STRENGTH ENVELOPES WERE OBTAINED FOR THREE STRENGTHS OF 0.375 IN. (10 MM) MSA ALL-LIGHTWEIGHT AGGREGATE CONCRETE: 2 KSI, 3.5 KSI, AND 5 KSI (140, 245, AND 350 KGF/SQ CM). THE DESIRED STRESS STATE AND THE ELIMINATION OF FRICTION WERE ACHIEVED BY LOADING THE SPECIMENS THROUGH WIRE BRISTLE COMPRESSION PLATENS IN A SPECIALLY DESIGNED TWO-CHANNEL, CLOSED-LOOP, ELECTRO-HYDRAULIC TESTING FACILITY. IN CONTRAST TO A PREVIOUS INVESTIGATION, THE SHAPE OF THE FAILURE ENVELOPE WAS FOUND TO DIFFER FROM THAT FOR REGULAR WEIGHT CONCRETE. FURTHERMORE, AN INVESTIGATION OF THE INFLUENCE OF LOADING PATH SHOWED THAT TWO-STEP SEQUENTIAL LOADINGS RESULTED IN STRENGTHS SIGNIFICANTLY LOWER THAN THOSE OBTAINED BY PROPORTIONAL LOADINGS. /AUTHOR/