The Research On Shrinkage Performance Of Carboxylic Acid Concrete

Because of the concrete material has the strength, plasticity,durability and its raw materials are easyto get, and the cost is low, it has become the most widely used, the most successful building materials, sofar. It improved the performance of the original concrete by mixed with concrete additive in many ways,such as: improved performance and intensity, the compaction degree also increases after hardening, but atthe same time, it brings some problems, such as shrinkage cracking phenomena are serious, so this paperstudy concrete’s shrinkage from three macroscopic aspect,that are admixtures, water-binder ratio andfiber.This article determines the selection of the cement type, through the cement slurry flow method,measures concrete early shrinkage by used the eddy current sensor non-contact method, measures concretelong-term shrinkage through the dial indicators. In this paper the experimental research the influence to theconcrete’s shrinkage which mixed with carboxylic acid admixtures by various factors.First this paper makes sure that carboxylic acid admixtures better adaptability with P.O42.5R levelordinary Portland cement, the optimum content at about2.0%,cement slurry net flow degrees will improvewith the increase of admixture, but if the admixtures overdose, there will find that cement slurry appearsecrete water net phenomenon.Secondly, this paper studies the shrinkage of concrete influence’s factors that is admixtures, fiber andwater cement ratio: after mixed with water reducing agent,the concrete’s shrinkage are increased in thesame proportion, But carboxylic acid admixtures has relatively good shrinkage effect, compared withnaphthalene admixtures. The carboxylic acid concrete’s shrinkage by adding15%fly ash and not mixed flyash are almost the same, along with the increase of the fly ash content to25%of the concrete the reduceshrinkage effect is obvious; by adding slag powder, can lead to the early hydration volume rapid expansion,so by adding to reduce acid salt ore together early concrete cracking has significant effect, relative to flyash for its reduced by adding more effect is better; By adding alkali-resisting glass fiber, in highwater-binder ratio, though not very apparent shrinkage effect, but because its improved the tensile strengthof concrete, so its crack effect is obvious, in the low water-binder ratio, fiber on early reduced has certaineffect, but from long-term standpoint, its increase the concrete’s shrinkage;in the carboxylic acid concretewith different water-binder ratio, along with the water-binder ratio cut, the concrete’s shrinkage valueincrease, and the lower the water-binder ratio, the more obvious early contraction.Finally, through contrast test, research the concrete’s mechanics properties by adding admixtures, fiberand change the water cement rati, and analyzed the influence of those factors to the mechanical properties.