Papers by Author: Zhi Hua Hu

Abstract: Non-fired load-bearing wall brick was prepared utilizing non-treated original waste PG as raw material in the laboratory. When the amount of PG and cement is 65% and 10% (by weight) in the brick mixture, respectively, the compressive strength of bricks is still over 23MPa and the flexural strength comes up to 4MPa. Besides, the bricks hold excellent water-resistance and frost-resistance. Effects of steel slag or/and fly ash content on performance of bricks and effects of the change of sand content on water-resistance and frost-resistance are discussed. Results indicate that the compressive strength, flexural strength and soft coefficient are higher when blended mineral additive with various amounts of steel slag and fly ash. The frost-resistance goes up with the increase of the steel slag content, the water-resistance and frost-resistance goes down when the sand content decreases from 15% to 10%, no matter the 5% sand was replaced by fly ash or steel slag as equal weight. Microstructure of brick was investigated by XRD and SEM. Strength of brick results from a large amount of AFt (3CaO•Al2O3•3 CaSO4•32H2O) and C-S-H (calcium silicate hydrate) presented in the matrix which may be viewed as the biggest strength contributors bonding the gypsum and quartz together to a compact matrix.

Abstract: The feasibility of manufacturing non-autoclaved aerated concrete using alkali activated phosphorus slag as a cementitious material was investigated in this paper. Liquid sodium silicate with various modules (the molar ratio between SiO₂ and Na₂O) was used as alkali activator and a part of phosphorus slag was replaced with fly ash which was used to control the setting time of aerated concrete. The influences of the fly ash, curing procedure, modulus of sodium silicate solution and concentration of alkalis on the compressive strength and bulk density of non-autoclaved aerated concrete have been studied. Moreover, the types of the hydration products were investigated using XRD and SEM. The results indicate that: the compressive strength of aerated concrete was influenced by concentration of alkalis obviously. The compressive strength of 11.9MPa and the bulk density of 806kg/m³ were obtained with an activator of 1.2 modulus of sodium silicate and 6% concentration of alkalis under the circumstance of 60°C curing for 28 days.