3 Grace Construction Products ASCP Presentation Niki Jackson 0434 183 639 niki.jackson@grace.com November 10th 2014
Grace History AGENDA Grace History and ancient art of Water Reduction. Theory of Dispersion. Cement dispersing technology. Lignosulfonates. Polycarboxylates (PC) Types of Polycarboxylates MIRA ADVA Advantage of PC Technology.
Grace History Founded in 1854 by Irish emigrant, Mr William Russell Grace. William Russell Grace became Mayor of New York & in 1885 accepted the Statue of Liberty from the people of France riginally a shipping & commodity chemicals company Purchased Dewey & Almy construction chemical business in 1954. In Australia for over 70 years Grace are a premier specialty chemical & building materials company who employ 6000 employees in over 40 countries
The ancient art of Water Reduction Ancient Admixtures Black grain molasses Milk Lard Animal blood & fats Cactus juice
Theory of dispersion Cement, C 3 A, C 3 S,C 2 S &C 4 AF plus Gypsum( CaS 4 ) Medium-Water Large rganic polymers Polycarboxylates ( PC s), Gluconates,Lignins & Na/Ca Napthalenes NB: The Silicates ( 75-80% of cement) are the main components that we disperse, they provide the strength in concrete.
Flocculation of Cement and Water Trapped Water Cement When cement is mixed with water, cement grains entrap water to form clusters or flocs. The trapped water can not easily contribute to the workability of the plastic concrete, and causes non-uniform cement hydration.
Without Admixtures Flocculated cement particles sand Hydrating cement
Water Reducers act as floc busters releasing the entrapped water -- Freed Water W/R Cement Water Cut (Lower W/C Ratio): Lower water/cement ratio means improved concrete quality. High Workability: Increased workability means easier placement, reduced equipment needs, and lower labor costs.
With Admixtures Dispersed cement particles. More complete hydration Higher Compressive strengths sand
Cement dispersing technology Lignin By product of timber industry, introduced approx 40 years ago Base raw material for water reducers Changes polarity of cement particles Sludge issues in tanks Napthalenes Introduced approx 20 years ago Base raw material for superplasticisers More effective disperser of cement versus lignin sulphonates Retardation effects at high dose rates Polycarboxylates (PC s) Introduced to concrete industry in 2000 s PC s are synthetically made, by product of petroleum / crude oil industry Technology originally used in self compacting / super workable concrete markets
LIGNSULFNATES Waste Liquor from sulfite pulping operations Lignin is sulfonated to Lignosulfonate a complex anionic polymer with numerous other stuff sugars and resinous acids Worldwide >Most widely used raw material for cement dispersion Common forms used is concrete are the calcium and sodium salts of lignosulfonate. Grace uses both soft and hardwood derived liquor. Dispersion --> Good water reduction (5-15%) Retardation at higher doses [ie. > (500 ml/100 kg) WRDA GWA] Possible 1-3% air contribution. Some sludge and biodegradation is unavoidable. Long service record
Structural Model Softwood Lignosulfonate Phenolic H Aliphatic H Sulfonate Methoxyl CH 3 H H - 3 S S 3 - H H CH 3 H H - 3 S 3 CH 3 - C - 3 S Carb. CH 3 H S 3 - CH 3 H CH 3 H CH 3 CH 3 H - 3 S - 3 S C - S 3 - H Carb. H CH 3 CH CH 3 - C S 3 - H S 3 - CH 3 (Adapted from Adler's struc Courtesy of Lignotech CH 3 H CH 3
Exploiting the wonderful World of Polycarboxylates Polycarboxylate Comb Polymer can be designed for : High early strength High slump/flow CH2 CH CH2 CH CH2 CH CH2 CH CH2 CH a b c d Long Slump life without extended C C set C C C WR.MWR & HWR Development H H3C H3C NH3 CH CH2 CH2 CH2 x CH CH2 y CH3 H3C H3C NH CH CH2 CH2 CH2 x CH CH2 y CH3 H3C H3C N CH CH2 CH2 CH2 x CH CH2 y CH3
Cement dispersing technology Polycarboxylate chemicals are very effective cement dispersers Water reductions in concrete mix of 5-40% PC s allow the water to react with all of the cement/scm particles Therefore less water required to achieve given slump Means less cement or greater concrete strengths Works in 2 types of cement dispersion methods Electrostatic Repulsion (charge repel) Static Repulsion (physical)
Dispersant Mechanisms Electrostatic repulsion Adsorbed charged molecules and polymers cause particle dispersion through repelling force of like charges on the surfaces of adjacent cement grains Steric repulsion Physical force produced when two adsorbed polymers try to occupy same space in the pore water.
Water Reducer Materials Polycarboxylates- (PC) Synthetically made 45-70% active liquids > Supplied to Grace. Dispersion --> Water reduction (5-40%) PC s are used in all common WR, MWR & HWR. Will entrain air and increase AEA efficiency> Require de-foamers Many types > have different functions ie water reduction or Slump retention No sludge. Formulated with various chemicals to achieve different properties. Historically, have been used in HWR for 10yrs, WR & MWR for 6 yrs.
Interfacing PC Structure and Application General Purpose PC/PS Slump retention
ther facts about WR & WRRe If possible all PC based WR should be added in the delayed mode.ie After 75% water. PC based Type WR are protected with biocides. Majority of water reducers have a de-foamer package. If verdosing occurs, Retardation will occur, Minimal air entrainment No Dis-colouration of concrete as we had with lignins.
MIRA Mid-Range Water Reducers
Concrete with MRWR MWR treated concrete has excellent workability, while maintaining high quality and low water/cement ratios
Finish Enhanced Concrete Scanning Electron Photomicrograph of Concrete Surface: (a) MRWR (b) Type A WR
MRWR Applications Residential Flatwork Commercial Flatwork Suspended slabs Formed Walls Manufactured Sands concrete Concretes with Pumping Difficulties Extruded/Slipformed concrete Coloured Concrete Long life concrete, tremmies Concrete Panels
ADVA High-Range Water Reducers
Comb Superplasticizers - ADVA Cement Dispersion by steric repulsion ++ + + + Water E/P Hooking Units - polycarboxylate Cement Cement ADVA Comb polymer Steric Repulsion Force
Superplasticisers Superplasticiser usage in 1998 200,000m3> Napthalene Based Types: Superplasticiser usage in 2010 2,000,000m3 Polycarboxylate technology highly effective cement disperser High Range Water Reducer - HRWR Water reduction of 20-35%, minimum 32Mpa mixes Various applications Increases flow-ability / slump Low Water Cement Ratio requirements Low Shrinkage Mix requirements Long slump retention times (Adva 320) ie piling used in conjunction with Daratard 1000 High strength gain and/or rapid set time ie pre-cast concrete (Adva 485) Self Compacting Concrete (SCC) / Super workable concrete Dose Rates Typically 300-800ml/100kg Dosed either up-front with batch water or placed at rear Typical slumps of 150mm 250mm As increase in dose rate, water reduction improves & set time decreases (faster set) Re-temper only once within 1 hour ( preferably)
Advantages of PC Technology Low dosage: 20% to 40% of NSFC Slump retention Setting characteristics can be controlled easily. Less sensitivity to addition time and cement chemistry Predictable dose-slump response Improved finishability; no spotty set Less bleeding, more cohesive rheology Minimal set extension when overdosed All PC based water reducers are sludge free> Less maintenance costs. Can be engineered for many many diverse applications