Experimental Research On Drying Shrinkage Of Unreinforced Masonry And Joint Reinforced Masonry

In order to meet sustainable development requirements of energy-saving land-saving, material-saving and recycling,unburnted brick has been widely used. However, unburned brick masonry is prone to crack due to its large drying shrinkage ,which affecting appearance, lower external wall insulation performance and durability of structures. Previous studies of single brick drying shrinkage more, but less on dry shrinkage of masonry, reinforced masonry in the dry shrinkage is rare. joint reinforcement can not only improve the overall and seismic performance, but also reduce the wall deformation, resistance to cracking. On the base of previous study on brick, the drying shrinkage of masonry and joint reinforcement masonry were further studied.The drying shrinkage of brick was effected by material,temperature,humidity and other factors,the specimen surface exposed to six. The brick in masonry is part of the surface exposed, and the masonry, water was absorbed from the mortar to brick, increasing moisture content. In this paper, Through four groups V/S ratio of the autoclaved fly ash bricks drying shrinkage test in dry environment, the effect law of the drying shrinkage of masonry on the V/S ratio was obtained .by eight groups of different ages the new brick masonry test, the law of water was absorbed from the mortar to brick was obtained.the factors affecting on Moisture content was amended. On this basis, the comprehensive existing results. the drying shrinkage prediction model of without reinforcement of unburnted brick have been presented.Masonry was composite material mading from bricks and mortar, brick and mortar can be considered as the isotropic elastic material.By using composite material mechanics principle of hygrothermal effects, the drying shrinkage strain relationship of masonry,bricks and mortar was derived.the drying shrinkage strain of masonry was equal to brick's in masonry ,and the impact on mortar was little. This conclusion was supported by the drying shrinkage test results of two concrete perforated brick and lightweight aggregate concrete hollow brick masonry.Based on the elastic creep theory, the factor of joint reinforcement unconsidering creep and considering creep on drying shrinkage of masonry was obtained by the analysis of creep effect of masonry.Through the drying shrinkage test of three concrete perforated brick masonry specimen with different reinforcement ratio in the dry environment, it was showed that the joint reinforcement can validly reduce the drying shrinkage deformation of masonry, and the calculation considered creep of the joint reinforcement factor and experimental results are in good agreement.Finally, in accordance with the bond slip relationship between steel and masonry, the calculation of crack width, crack spacing was obtained,and the minimum reinforcement ratio in end-restrained reinforced masonry was disussed.