Tests on high-performance aerated concrete with a lower density

摘要

The present study tested 16 concrete mixes to develop a high-performance aerated concrete without using high-pressure steam curing processes, as an alternative to autoclaved aerated concrete (AAC) blocks. To achieve high-strength gains, particularly at an early age, for aerated concrete under an air curing environment, the binder and chemical agent were specially contrived as follows: The loss on ignition of ordinary Portland cement was controlled to 1.5% and 3% anhydrous gypsum was then added; and the content of polyethylene glycol alkylether in a polycarboxylate-based water-reducing agent was modified to 28%. Furthermore, a foaming agent based on a protein-hydrolization with enzymatic active components was used to generate independently closed pores during concrete mixing. The test parameters investigated were the foaming volume rate (V_f) of the preformed foam, water-to-binder ratio (W/B), and unit binder content (B). The qualities of the developed high-performance aerated concrete were compared with the minimum requirements specified in ASTM C 1693 for AAC and with data of existing conventional aerated concrete. Prediction models for dry density, compressive strength, stress-strain relationship, and thermal conductivity of aerated concrete were formulated from the regression analyses of the test data. All concrete mixes investigated displayed enhanced workability and defoaming resistance, achieving self-compactability performance. Furthermore, the measured mechanical properties prove that the developed high-performance aerated concrete has considerable potential for practical application when B is approximately 550 kg/m~3 and when W/B ranges between 30% and 25%, at which it fulfils the minimum requirement for class AAC-4 of ASTM C 1693.