Papers by Keyword: Manufactured Sand (MS)

Abstract: Effect of the different contents of limestone power (LSP) in manufactured-sand (MS) is investigated in respect of the workability, setting time and compressive strength. The results show that the contents in a certain range can significantly increase the consistency, Specific density of the fresh mortar, and improve comprehensive strength of the hardened mortar due to LSP deduced the porosity and improved the pore structure.

Abstract: The influences of sand-cement ratio on bulk density, fluidity, compressive strength, flexural strength of mortar of river sand, limestone manufactured sand (MA), quartzite MA, granite MA were studied compresively in the paper. The results show that bulk density of mortar reaches to maximum if sand-cement ratio of mortar of river sand is 2.73 and the ratios of mortar of manufactured fine sands are all 3.0. The fluidity of mortars of river sand and limestone MA are better than those of quartzite MA and granite MA. Sand-cement ratios of mortars with maximum strength are equal to that with maximum bulk density. The sequence of compressive strength is limestone MA, quartzite MA, river sand, granite MA from high to low, and that of flexural strength is limestone MA, quartzite MA, granite MA, river sand.

Abstract: Concrete lining is commonly used in large channel project to fixup soil slope and prevent channel seepage. Concrete lining is a type of thin plates structure which should have the high compression strength, crack resistance and durability. Two new high performance concrete (HPC) are used in lining project of south main channel of Yellow River-crossing project in east-route of the South-to-North Water Diversion Project. One is flyash HPC with manufactured-sand and the other is HPC with cementitious capillary crystalline waterproofing material (CCCW); meanwhile, the mix proportion of flyash HPC with manufactured-sand and HPC with CCCW are recommended. For flyash HPC with manufactured-sand, the recommendatory water-binder ratio is 0.4 and the recommendatory flyash content is 30%. For HPC with CCCW, the recommendatory water-binder ratio is 0.48 and the recommendatory CCCW content is 1.5%.With the wide application of new HPC, the compression strength, crack resistance and durability of lining concrete are improved, channel seepage discharge is reduced and a large amount of natural building materials are saved.

Abstract: The effect of mineralogical origin, elemental component, crystal structure of three types of limestone powder on the fluidity of cement-limestone paste and mortar was investigated. The results show that the limestone powder originated from the mine of limestone and river pebble have better water-reducing effect, which is closely correlated with the main components of Calcite and Dolomite. These two mineral have relatively regular, orderly and perfect crystal structure with few defects and unfilled pores which are liable to adsorb more water and water-reducing agents. On the contrary, the limestone powder derived from the mine of sandstone has nearly no water-reducing effect which is ascribed to the large amount of clay mineral which exhibit lamellar structure leading to the large quantity of consumption of water.

Abstract: The workability, strength and modulus of elasticity, drying shrinkage and creep, and chloride ion permeability as well as freeze-thaw resistance of the C60 high Performance concretes (HPCs) with manufactured sand (MS) containing crushed limestone dust in percents ranging from 3.5% to 14% were experimentally investigated. The results were compared with those of river sand (RS) concrete. In addition, the effect of clay amounts at 3% and 5% in MS on properties of C60 HPCs was also investigated. The results showed that expect for the creep, the other performances of C60 MS-HPCs with crushed limestone dust content of 7% to 10.5% were excellent or compared favorably with those of C60 RS-HPCs. The increment of clay content in MS obviously decreased workability, increased dry shrinkage and accelerated freeze-thaw destruction of C60 MS-HPCs, but didn’t affecting compressive strength and chloride ion permeability of the concrete. It was concluded that C60 HPC can be made with MS with a high content of crushed limestone dust but the amount of clay in MS should be controlled to a low limit.

Abstract: This paper researches on the feasibility of preparing ultra-high strength & high performance concrete with low quality fine aggregate, such as super fine sand (fineness moduls≤1.10), chippings and manufactured sand. The results shows: with low quality fine aggregate, ultra-high strength & high performance concrete can be prepared, and with excellent fluidity and a compressive strength range of 70~120 MPa.