Papers by Keyword: Concrete Admixture

Abstract: Concrete has not only fulfilled the load-bearing function, but also its aesthetic function comes to the fore. It is precisely coloured concrete that performs this function best. The second phenomenon of today is "green concrete". In the paper, the properties of coloured concrete are compared with its "greener" alternative - coloured concrete with fly ash as a binder substitution. Experimental samples were measured for compressive strength and water absorption over a period of 7 days to 2 years. The results showed that the combination of coloured pigment and fly ash has an interesting synergistic effect, as evidenced by a 45MPa compressive strength and a 15% decrease of water absorption.

Abstract: In this paper, cationic polycarboxylate superplasticizer has been synthesized by using room temperature process with HPEG, AA, DAC and 3-S as the main raw materials. We investigated the effect of the dosage of different raw materials on the dispersing property of polycarboxylate superplasticizer, and we knew that AA: DAC: HPEG: 3-S = 4.5: 0.05: 1: 0.12 was the best molar ratio, the synthesized cationic polycarboxylate superplasticizer had excellent dispersity and mud resistance, and it was superior to commercially available ordinary polycarboxylate superplasticizer.

Abstract: Concrete from ready mix plant is the main raw material consumed in construction industry. A significant waste quantity is generated with fresh concrete returned to the production center due to their inadequate allocation or demand preview. To minimize the amount of this material wasted, misused, discarded, could be used the Hydration Stabilizer Admixture (HSA). This product enables stabilization of the concrete setting time until 72 h. Waste generated by the building industry is becoming increasingly focused on discussions and studies, due to great importance that this topic is achieving. Generation of this waste in the construction sector and the large representation of this sector in society is one of the main problems encountered in the reuse of waste from construction. Its characteristic, heterogeneous and unknown, however, a specific part of that waste generated in the central metering concrete, has a high potential for reuse, mainly because they come from a production highly controlled, where the source materials and the final product are physically and chemically known. This work aims to study the environmental benefits and technical feasibility of stabilizing additive hydration as a solution for the reuse of residual concrete from central metering, always under a sustainable vision of the entire process through an experimental program. This work presents results of setting time, slump test, incorporated air, compressive strength at 3days, 7days, 14days, 28days and 45 days and elastic modulus ate 28 days. The reference concrete was compared with concrete stabilized mixtures (0.15%, 0.30%, 0.45% content of HSA), both presenting the same constituent materials. The results indicate the feasibility to the use of the HSA despite the reduction of the mechanical properties of the concrete.

Abstract: The article issued the influence on concrete durability caused by concrete admixture, based on the further study on concrete admixture bleed air performance test, and researched the influence on concrete durability caused by it. The experiments show that the admixtures of air-entraining performance improve internal pore structure of concrete and increase the compacting condition concrete. Concrete admixture also can improve the impermeability of concrete frost resistance and improve the resistance to environmental actions, and proposed concrete air content of the Dalian region suitable value.

Abstract: Concrete admixture is a kind of addition agents, which can improve the performance of concrete. Adding a certain amount of concrete admixture can enhance the early strength, the age strength, and the anti-permeability strength of concrete. Also, concrete admixtures can improve the workability and adjust the setting time of concrete, so as to reduce the dosage of concrete and save the cost of concrete. This paper describes the types of concrete admixture and their functions, studies the functions of water reducers, and analyzes their effects to concrete, so as to improve the concrete performance and save materials in actual operation.

Abstract: For concrete structures in chloride containing environments, hydrophobic surface treatments are often used as an additional protective measure for protecting the embedded steel against corrosion. In recent years, silane-based hydrophobic agents that can be used as concrete admixtures for making the whole concrete hydrophobic have also been introduced. In the present paper, the protective effectiveness of such an admixture against chloride penetration has been investigated. For comparison, some field investigations on the effectiveness of a traditional surface hydrophobation of two concrete harbor structures based on similar products are also briefly reported.

Abstract: Paper studies on phosphorus slag powder(PSP) processed from phosphorus slag with different open-air storage time, analyses the changes in the performance of PSP and the impact on properties of cementitious materials. The results showed that with the growth of open storage time, vitreous structure of PSP would gradually be decomposed, part of the vitreous would transform into crystal form. Density of powder would diminish and ignition loss increase. Activity of PSP would slowly decreases, and the activity differences main reflected after 90d. Concerning on the point of concrete strength rating, 10 years phosphorus slag can still be used. The above provide a basis for resource utilization of phosphorus slag with long storage time.