Damage-acoustic emission characterization of basalt fiber foam concrete under freeze-thaw environment

The uniaxial compression-acoustic emission tests were carried out on four different basalt fiber admixture (0%, 0.15%, 0.30%, and 0.45%) foam concrete (BFRFC) specimens at 600 and 1000 densities in different freeze-thaw environments (0, 20, 40, 60, and 80 freeze-thaw cycles) to investigate the effects of density, fiber admixture, and number of freeze-thaw cycles on the uniaxial compression performance of BFRFC. The compression damage model was established based on the acoustic emission and uniaxial compression parameters to quantitatively analyze the damage of BFRFC under different freezing and thawing cycles. The results show that: BFRFC has obvious stages in the compression process, which are divided into four stages of dense, elastic, yield and platform, and the acoustic emission characteristics show three stages of contact, steep increase and slow increase; the strength loss rate of each specimen under different numbers of freezing and thawing cycles ranges from 3.4% to 63.6%; the freezing and thawing environment would reduce the activity of acoustic emission, which would seriously affect the mechanical properties of BFRFC; basalt fiber doping causes the cumulative ringing number of the specimen to increase and then decrease, which could slow down the loss of peak strength to a certain extent; Freeze-thaw cycle accelerates the crack development, basalt fibers could effectively inhibit the development of cracks, but the fiber agglomeration phenomenon is highlighted at high doping, and the internal damage is aggravated; The damage of the BFRFC in the pre-pressure stage is low, and the damage development is accelerated at the relative peak stress of more than 0.7, until the damage is damaged.