Effects of fly ash and ground granulated blast-furnace slag (GGBFS) on workability, strength, volume stability and durability of HSC are investigated. Results show that fly ash and GGBFS can improve the workability, increase the later strength of high strength concrete (HSC) remarkably, and reduce the brittleness. In addition, the ameliorative effect of GGBFS on HSC brittleness is more remarkable. With the increase of fly ash and GGBFS, the early elastic modulus of HSC reduces. The elastic modulus is similar to the controlled sample when the load is applied after 60d curing. The fly ash and GGBFS can improve HSC’s resistance to chloride ion penetration significantly. However, the effects of fly ash and GGBFS on freezing-hawing resistance of HSC are not obvious. Besides, the fly ash will reduce freezing-hawing resistance of HSC only when the content of mineral powder is up to 36%.
It is difficult to control quality for precast concrete girders in curing, so we set up the curing system of precast concrete girders with computer networks, automatic control of drip irrigation technology, database technology and two-dimensional code technology, With which we can control concrete girders curing continuously. Achieve well curing results, and storage the precast girders curing process temperature and humidity data, provide the data basis for quality assessment and acceptance of post-concrete structure.
In this experiment, four kinds of pervious concrete with different porosity (10%, 15%, 20%, 25%), four kinds of paste coating thickness (0.3mm, 0.5mm, 0.7mm, 0.9mm) and four kinds of thickness (30mm, 40mm, 50mm, 60mm) were prepared and their sound absorption coefficients under different frequency bands were tested. The results show that with the increase of target porosity, the thickness of paste coating and the thickness of pervious concrete, the sound absorption coefficient of pervious concrete increases firstly and then decreases. Through comprehensive consideration, when the target porosity is 18%, the thickness of paste coating is 0.5mm and the thickness is 40mm, pervious concrete has the best noise reduction effect. It provides a technical basis for the design of pervious concrete with noise reduction function.
the influence of mixing amount of mineral admixture, volume content of fine and coarse aggregate have been systematical studied on the workability, mechanical properties and volume stability of self-compacting concrete. Test results showed that with the fly ash content increased, the workability of self-compacting concrete improved significantly, early compressive strength decreased, but increase rate of later strength improved remarkably, and the mixing amount of fly ash inhibited significantly the dry shrinkage of self-compacting concrete; with the volume content of coarse aggregate increased, the workability of self-compacting concrete decreased significantly, but the volume stability of self-compacting concrete improved obviously, thus the optimum volume content of coarse aggregate of self-compacting concrete was range from 0.30 to 0.34; when the volume content of fine aggregate varied at the range of 0.40~0.50, there may be little effects on the workability of self-compacting concrete, but the increase self-compacting concretes volume content could reduce obviously the dry shrinkage of self-compacting concrete. Moreover, the variation in the volume content of coarse and fine aggregate should have slight influence on the early strength of self-compacting concrete, and the influence of the volume content variety on the later strength of self-compacting concrete could be neglected eventually.
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