COMPARISON OF DURABILITY OF DIFFERENT KINDS OF LIGHTWEIGHT AGGREGATE CONCRETES

To study the correlations of influence factors between strength and durability for lightweight aggregate concrete (LWAC), a serial of tests on compressive strength, carbonization depth, chloride ion penetration and sulfate attack were carried out. Where the tested concretes include all-lightweight shale ceramsite concrete (ALWSCC), ALWSCC replaced part of fly ash with limestone powder (LSP) in equal mass, chopped basalt fibers (CBF) reinforced ALWSCC, the LWCSFA, LWCSCA and HLWC made from ALWSCC replaced shale pottery and shale ceramsite with river sand and normal coarse aggregates in equal volume and in single or double methods accordingly, respectively, and the corresponding self-compacting LWACs (SCLWCSFA, SCLWCSCA and SCHLWC). The results showed that the durability indexes of different kinds of LWACs were closely related to concrete type and strength grade, but the strength indexes were out of step with the durability indexes. The LSP, CBF and normal weight aggregates could effectively improve the carbonation resistance of LWACs, and the self-compacting LWACs were better. The modified carbonization model of normal weight concrete (NWC) was suitable for LWAC. The quantity of electric charge through LWACs showed a great differences at 28 d, but it was significantly reduced and approached at 56 d, and the resistance chloride ion permeability of CBF reinforced ALWSCC and SCLWCSFA were better. The loss rates of compressive strength (k) and corrosion resistance coefficients (K_f) of different kinds of LWACs were similar, respectively, and which exhibited synchronism and strong correlation under the same dry-wet cycle times. However, only the k and K_f of self-compacting LWACs increased first and then decreased with the increase of dry-wet cycle times.