Experimental Study On Pumping Concrete With Waste Fly Ash

There’s a vast amounts of waste fly ash in China, but the use of waste fly ash is relatively small. In this paper, experimental research shows that after treatment waste fly ash was not as good as fly ash with good quality, but fresh concrete can get a good performance if we use in conjunction with the admixture.It doesn’t affect the construction of concrete pumping, while the hardened concrete has good mechanical properties and volume atability. We can provide a basis of the theory and practice to the utilization of waste fly ash in the future, so that we can improve the utilization of waste fly ash.For the use of waste fly ash, there are two technical routes:First, use the fly ash as a raw material of cement, that is, adjust the proportion of fly ash and the cement clinker and the gypsum, to make out cement with good performance, make the cement into pumping concrete, and study the perfonnance influence of concrete; Second, the fly ash will be used into the pump concrete in the form of an admixture, and the influence on the performance of the concrete will be studied.Study on waste fly ash cement used in pumping concrete:Experimental Study on Pumping Concrete with Waste Fly Ash is disscused in this paper. First, we did some performance detection of the waste fly ash, it has a big moisture content and a large particle size, the water requirement ratio is high, the 45μm screen cushion and the loss on ignition is high, and all of this is far from the national standards. So that we try to stimulate the activity of the waste fly ash through the levigation test, change the grinding time to improve the screen cushion and the loss on ignition and the specific surface area. The experiment proved that the performance of the fly ash is improved after the 20min’s levigation.Study on waste fly ash uede in pumping concrete as an mineral admixture:Along with the increase of the fly ash content in the cement, the early strength of the pumping concrete decreases, when the content is 45%, the strength has a dramatic decline. With the increase of the content of fly ash, the concrete’s strength of the later age reduces, but the growth of the strength of concrete is better than concrete without fly ash cement. The research shows that when the content of gesso is 7%, the content of fly ash is 45% and the content of clinker is 48%, the cement mixed by the abandoned fly ash with levigation has the minimum water demand for normal consistency of the resultant cement, the strength of the mortar decrease, but the strength could still satisfies the requirement of the mortar strength. The performance of the raw fly ash cement is poor, but when mixed the dry fly ash and the raw fly ash together, the performance of the cement is best, and is close to the performance of fly ash cement with 20min’s levigation. This article studied on the content and the quality of the fly ash. Research shows that the quality of the fly ash influence the performance of the mortar and the concrete deeply, the performance of the concrete which made up with bad fly ash is low, but the study found that we can get a effection by increasing the content of the bad fly ash. Because of the low cost of the fly ash, we can get a effection by increasing the content of the bad fly ash. But the bad fly ash will reduce the quality of the concrete, so the content of it has to be appropriate, it’s appropriate to be less than 30%. When the content of the pumping aid is 2.0%, the slump of the pumping concrete mixed with a 30% of fly ash can be up to 190 mm.Water reducing agent exerts a tremendous to the concrete, this paper discusseed the influence to the working performance and strength of the concrete by five different water reducing agent. In the five water reducing agent, the polycarboxylic acid type high performance water-reducer and the aliphatic department water-reducer improved the performance of the concrete deeply, and the content is lowest. The paper also studied on the adaptability of five types of water reducing agent with the homemade abandoned fly ash cement, among them with together, the polycarboxylic acid and the aliphatic department and the aminosulphonic acids type high performance water-reducer has the best adaptability with the cement, which can make a good effect. In order to get a better pumpability, we try to mix the superplasticizer and two other concrete additive together. The results show thatwe can improve the performance of the concrete with the aliphatic department high performance water-reducer and retarder and air-entraining agent together.Study on the microscopic of the pumiping concrete:It can be seen by X-ray diffraction patterns and SEM scanning electron microscopy figure that, pumping concrete mixed with waste fly ash impact on the early hydration of the concrete is relatively large. The concrete structure with fly ash was loose than the concrete structure without fly ash in the 3d age, it had bigger porosity and smaller hydration products. In 28d age, both the density of the concrete structure is basically the same. After 20min’s grinding with the ball mill, the particle diameter and the number of large particles of waste fly ash was significantly reduced, and the particle size distribution is relatively good.