Properties Of Modified Welan Gum And Study Of Its Effects On The Performance Of Concrete

Welan gum has good rheology,efficient anti-bleeding and thickening properties.But the competitive adsorption between welan gum and other superplasticizers especially polycarboxylate superplasticizer(PCE)has been existed remarkably while adding together due to its long side-chain existence and powerful charge density in molecular structure.In this paper,new kinds of welan gum product named modified welan gum(MWG)which has good compatibility features with the superplasicizers has been invented with optimizing the preparation technology and the core material.But its effects on mortar and flow state concrete are not clear yet.Therefore,the effects on the mortar and flow state concrete have been investigated on the basis of discussing the characteristics of the welan gum in order to providing theoretical and technical support for its application.In this paper,the properties of the MWG have been investigated include the dissolution property and the rheological property.With adding the MWG,the performance of cement paste(static exudation rate,water consumption standard consistency and setting time and rheological properties)and the effects on working performance and mechanical properties of cement mortar have been studied;The effects of the MWG on the work performance(slump,the slump spread,bulk density,the pressure bleeding rate and air content and 1 h slump loss),mechanical properties(7 d and 28 d intensity)and long-term performance and durability performance(early crack resistance,frost resistance,impermeability and wear-resisting performance)of flow state concrete have also been investigated.The results of the research show that(1)The solubility of the MWG decreases with the increase of mass concentration and has good shear thinning properties.The workability performance,the flexural strength and compress strength and the adhesive strength of the mortar will be improved with the MWG or MWG+PCE.The workability and the mechanical properties of the mortar will be improved with the MWG,so the competitive adsorption of the WG and PCE will be improved.The recommend dosage of the MWG(according to the effective dosage)in mortar is 0.01%-0.10%.(2)The slump,slump extending degree,1 h slump loss and 1h slump extending degree loss will be significantly improved with the MWG.The workability of the fresh concrete will be improved,especially to solve the problem of segregation and bleeding.And the early mechanical properties of the hardened concrete also will not be influenced.The recommend dosage of the MWG(according to the effective dosage)in the concrete is 0.01% to 0.03%.(3)The active components of the MWG is welan gum and it shows three-dimensional network structure when dissolved in water.So it can effectively delay the sedimentation rate of aggregate,reduces the thickness of pulp layer,improve the uniformity of hardened concrete and the compactness,improve the structure of space.Then the frost resistance,impermeability,crack resistance and wear resistance can be effectively improved with the add of MWG.