Preparation And Performance Of High Flowing Lytag Concrete

The lower density and higher insulating capacity and better durability are the most obvious characteristics of Lytag-based lightweight aggregate concrete (Lytag concrete) by which it distinguishes itself from ordinary normal density concrete. However, it is difficult to obtain good workability and uniformity at the same time because of its special constitutes and structure, in which Lytag lightweight aggregate can be characterized as lower density, lower grain strength and rough and porous surface structure. Therefore, investigating and triumphantly preparing Lytag concrete with good fresh properties and harden properties are always the top-priority questions in the field applications of Lytag concrete. And these investigations are no doubt important and they will certainly promote the application of the Lytag concrete in large-scale and important structure project extensively.In this thesis, the rules of shearing strength varied with the shearing time after adding slag, fly ash, zeolite powder and silica fume at different ratios into the pure cement paste are studied. After making the fluidity of cement paste clear,the optimized mix proportion of high strength Lytag lightweight concrete were designed. And then the Mechanics properties and durability of high strength Lytag concrete have been studied in more detail.The experimental results have been found as follow: (1) the plastic viscosity of the cement paste will decrease with the increase of slag or fly ash, but the yield shearing strength will increase gradually with the increase of slag or fly ash. (2) The plastic viscosity of the cement paste will go down with the gain of silica fume's dosage at first, and the plastic viscosity will reach a minimum value when the dosage of the silica fume is 8%, and then it will enhance with the increment of the dosage of the silica fume again. (3) The plastic viscosity of the cement paste will go up and yield shearing strength will go down with the increase of the ratio of the zeolite powder either the zeolite powder is added as a single agent or combined with silica fume. (4) The plastic viscosity of the cement paste will increase and yield shearing strength will decrease with the increment of the percentage of the fly ash when fly ash is combined with silica fume. (5) The plastic viscosity of the cement paste will increase and yield shearing strength will decrease with the increase of slag when the slag is combined with silica fume. (6) The rank of effect of the mineral admixture on the 28d compression strength of Lytag concrete: silica fume>slag>fly ash. And when two mineral admixtures are combined to add into Lytag concrete, the rank of effect of the mineral admixture on the 28d compression strength of Lytag concrete: silica fume and slag>silica fume and fly ash>slag and fly ash. (7) The elasticity modulus of Lytag concrete is lower than normal density concrete's and the peak value of strain of Lytag concrete is higher than normal density concrete's. (8) The single surface's frost resistance of Lytag concrete with mineral admixture is much better than normal density concrete's. And the rank of the single surface's frost resistance at 56 cycles of Lytag concrete with different mineral admixture is: silica fume and slag> silica fume and fly ash>slag and fly ash>silica fume>fly ash>slag.