2Water-Reducing Admixture DefinitionClassificationWater-reducing admixture in common useLignin sulfonate water-reducing admixtureNaphthalene sulfonate water-reducing admixtureResinous water-reducing admixturesMechanismTechnical and economic effects
3Water-Reducing Admixture DefinitionWater-reducing admixture permits less amount of water at the same of workability or the increase of the mobility at the same amount of water.Water-reducing admixtures increase workability and quality by use of water more efficiently in a concrete mixture. By reducing the water, these admixtures densify the concrete and decrease capillary voids and permeability.
4Classification by effect Water-Reducing AdmixtureClassification by effectIt can be classified into two types by effect:Ordinary water-reducing admixtureSuper plasticizerThe water-reducing rate of Ordinary water-reducing admixture is less than 10%.The water-reducing rate of Super plasticizer ,also called super plasticizer or fluid concrete is more than 10%.
5Water-Reducing Admixture Classification by the effect on setting timeThree typesStandard typeSet retarder typeCoagulant type
6Water-Reducing Admixture Classification by the effect on air contentTwo types by the effect on air contentAir entraining typeNon air entraining type
7Mechanism Water-reducing admixture (surfactant) is composed of hydrophilic group-polar grouphydrophobic group -nonpolar groupWhen mixed with waterhydrophobic group attaches to cement particlehydrophilic group attaches to water
8Mechanism hydrophobic group hydrophilic group Fig4.2.4 Sketch map of the structure of Water-reducing admixture
10MechanismMechanism of water-reducing admixture is reflected in the apparent active reaction.Cement paste flocculation structure is wrapped to reduce the mobility of the admixture.But water-reducing admixtures make flocculation structure dissolve so as to improve the mobility and strength.
11MechanismThe flocculation structure dissolves in the following three ways:Disassemble cement flocculation by electron repelling from the surface of cement particleImprove the fluidity of paste by forming a solvate membrane on the particle surfaceExtend the hydrating area by improving the dispersity of the cement particlesMobility is improved.
12Technical and economic effects Technical and economic effects of water-reducing admixture are listed in Tab4.2.10Tab Technical and economic effects of water-reducing admixtureGroupeffectsCement content （Kg/m3）W/CSlump（mm）fcu,k(Mpa)1.Base concrete( not of water-reducing admixture)3000.6250372. Improving mobility100383. Improving strength0.56464. Saving cement27037.5
13Water-reducing admixture in common use Lignin sulfonate water-reducing admixtureNaphthalene sulfonate water-reducing admixtureResinous water-reducing admixture
14Lignin sulfonate water-reducing admixture DefinitionLignin sulfonate(M) is the most common in use.It is made by wood pulp through sulfonation and dryness.Definition
15Lignin sulfonate water-reducing admixture PerformanceThe amount and its effectsIf % lignin sulfonate is addedThe water-reducing rate will be 10%Or increasing the slump by 10cmThe strength increased by 10-20%Performance
16Lignin sulfonate water-reducing admixture PerformanceSet retarder activityDelay the setting time 1-3hours, and add 0.25% Minto lignin sulfonate water-reducing admixture.Thus, it must be used with the mixture of hardening accelerator in winter.Performance
17Lignin sulfonate water-reducing admixture PerformanceAir entraining activityTo increase the air content from 2% to 3.6%So that the strength is reduced, while the durability is improved.Performance
18Lignin sulfonate water-reducing admixture ApplicationAccording to the performances, it applies tolarge mouldingsliding formworkmass concreteconcrete pumpingsummer constructionApplication
19Naphthalene sulfonate water-reducing admixture Brief IntroductionAt present, there are varieties of naphthalene sulfonate water-reducing admixtures in China.The types in common use include NF,NNO,FDN,UNF,MF,AF, and so on.Brief introduction
20PerformanceAdding %It has advantages over lignin sulfonate water-reducing admixture for its violent dispersionwater-reducing rate >15%reinforcing rate >20%saving cement 10-20%Minor set retarder activity doesn’t affect the strengthMost of them are non air entraining.
21Naphthalene sulfonate water-reducing admixture ApplicationNaphthalene sulfonate water-reducing admixture can be used inHigh strength concreteHigh performance concreteLiquid concreteConcrete pumpingWinter construction concreteApplication
22Resinous water-reducing admixtures IntroductionResinous water-reducing admixtures are one of superplasticizer.In China, as the main type of resinous water-reducing admixtures, SM has the perfect water-reducing effect.
23Resinous water-reducing admixtures AdvantagesIt is better than naphthalene sulfonate in dispersion, water reducing, and reinforcing.The 7d strength is the same with 28d strength of ordinary ones.The 28d strength can increase by 30-60%.DisadvantagesThe cost is high