CSA cement ( CSA binder )

Introduction

General characteristics

CSA Cement, also named Calcium Sulpho Aluminate Cement with grade: 42.5, 52.5, 62.5, 72.5, 82.5, 92.5, is a hydraulic binder based on calcium sulpho aluminate, rather than calcium aluminates which are the basis of Calcium Aluminates Cement or calcium silicates which are the basis of Portland Cement. It can be used on its own (with a Lithium accelerator), or with an Anhydrite, Portland cement mix, Metakaolin or a combination of all.

CSA Cement has the benefit of being readily adaptable to suit many different applications where both rapid set and / or high early strength gain are required. It yields controlled set, enhanced early strengths, shrinkage compensation or expansion and sulphate resistance. Uses include any cement-based product in need of these properties. CSA Cement products exhibit a range of properties to suit a wide spectrum of cement-based applications, like fast setting cements, self-leveling or self-smoothing compounds, self compacting concrete,rapid hardening mortars, tile adhesives, non-shrink grouts, water stopping mortars, repair mortars, high early strength concrete, GRC, etc.

Within CSA (Calcium Sulpho Aluminate) Cement Ettringite formation is typical. Ettringite is an expansive crystalline substance formed when sulphate reacts with tri-calcium aluminate (C3A) and calcium hydroxide (Ca(OH)2). It occupies twice the volume of the original compounds so an expansion occurs. In the CSA Cement, 85% of ettringite is developed at a very early stage in the process, before the aluminates and silicates start to hydrate. The risk of late ettringite formation is very limited and the ettringite which is formed is very stable over time. This is the fundamental difference between CSA and CAC (Calcium Aluminate Cement) Cement.

Be it a mortar or a concrete, making a composite cement which exhibits rapid setting, high early strength development, with little or no loss of late strength, no risk of conversion or late formation of ettringite. Depending on the level of addition of calcium sulphate, either shrinkage compensation or positive expansion can also be controlled.

Potential advantages of the CSA Cements are low CO2 emissions, improved sulphate resistance, low permeability, enhance durability and a good workability at low temperatures.

CSA Cement is manufactured under a strict quality assurance systems GB/T 19001-2000 (i.e. ISO9001:2000) and GB/T 24001-1996 (i.e. ISO 14001:1996)) which accommodates the technical requirements of building chemistry formulators.

Properties

Incorporation of Calcium Sulpho Aluminated Cement into a variety of mix designs, CSA Cement products exhibit a range of properties,like :

Rapid Set        Adjustable Setting Time       High Early Strength

Increased strength in time      Minimal Shrinkage       Shrinkage compensation

Expansion         Sulphate Resistance      Reduced Alkalinity

Low CO2Emissions     Rheology Adapted to the Application, etc.

Chemical Analysis

The chemical analysis of CSA Cement has been determined according to the following:

GB/T 176-1996 Methods of chemical analysis for cement.

Main constituents (%)

Component	Type I	Type II	Type III	Type IV	Type V
SiO2	≤7.0	≤8.5	≤10.5
Al2O3	≥36	≥35	≥34	≥32	≥28
Fe2O3	1.5-2.5	1.5-3.5	1.5-3.5
CaO	40.0-41.5	40.5-42.5	41.5-43.5
MgO	≤ 3.5	≤ 3.5	≤ 3.5
SO3	8.5-11.0	8.0-10.5	7.5-9.5
TiO2	1.0-2.0	1.0-2.0	1.0-2.0

Fineness

Specific Surface Area: according to standard GB/T 8074-2008:

Usual range: 400(+/-20) m2/kg, Specification limit: >360 m2/kg;

Usual range: ≥ 480 m2/kg, Specification limit: >450 m2/kg.

Mineral composition

C=CaO, A=Al2O3, S=SiO2 , F=Fe2O3,  S =SO3

−Principal mineral phase: calcium sulphoaluminate C4A3S-

−Secondary phases: C2S, C4AF

Notes: This information is given for reference only.

Hydraulic Properties

The characteristics of CSA Cement have been tested in accordance with the Chinese standards: GB20472-2006.

Setting time determined at 20℃, using Vicat needle according to GB/T 1346-2001.

Mechanical strength at 20℃, 95% relative humidity according to GB20472-2006 .

Item		Type I	Type II	Type III	Type IV	Type V
Bending Strength (Mpa)	1d	≥8.0	≥7.0	≥6.0
	3d	≥10.0	≥9.0	≥8.0
	7d	≥11.0	≥10.0	≥9.0
Compressive strength (Mpa)	1d	≥60.0	≥50.0	≥50.0
	3d	≥85.0	≥75.0	≥65.0
	7d	≥95.0	≥85.0	≥75.0
Setting time	Initial	≥25min	≥25min	≥25min
	Final	≤300min	≤300min	≤300min

Applications

These properties are applied to obtain a wide range of products:

 -   Rapid repair mortars

 -   Fast setting tile adhesives

 -   Fast setting tile grouts

 -   Shot-crete / Gun-nite

 -   External renders

 -   Self smoothing mortars

 -   Self leveling mortars

 -   Anchor bolt grouts

 -   Non shrinking grouts

 -  etc.

Use of Additives

CSA Cement may be used in combination with chemical additives such as:

 -  polymers, either in latex form or redispersible powder form

 -  defoamers

 -  retarders

 -  accelerators

 -  plasticizers/superplasticizers

 -  rheology modifiers

-  fibers

Reactivity with Portland cement

CSA Cement may be used in combination with other mineral products, for example Portland cement, calcium sulphates and fillers, or with organics such as polymers in latex foam or in redispersible foam.

Depending on the type of mixes and technology employed, CSA Cement can be used to obtain and control various properties.

The behavior of Portland cement is very variable. In general, acceleration of set increases progressively with the addition of HCSA Binder. The amount of HCSA Binder needed to obtain a specific setting time varies considerably depending on the origin of the Portland cement and performance can be modified with the use of additives.

The strength development of CSA Cement/Portland cement and/or Calcium Sulphates depends on the nature of the Portland cement and/or Calcium Sulphates used. In general these mixes will develop mechanical strength at a very early stage (several hours). With some type of Portland cements and in formulated products containing additives which control the setting and hydration, the long term properties is similar to those of the original Portland cement, however it is necessary to check the behavior of each Portland cement used.

The characteristics of Portland cement to be considered are:

C3A content

Mineral admixture type and content

Type of Calcium Sulphate used

Additives will also influence the properties of these mixes:

Setting time

Rheology

Mechanical performance

Storage

CSA Cement is normally supplied in one-tonne bag which include a moister resistant barrier. However, in common with all hydraulic binders HCSA BINDER must be kept from moisture, and can retain its properties for up to six months when properly stored.

Note: Edit by Jack Young, as references only. For more informations, please contact:

cell phone no.: +0086 158 1032 6158 or mail box: csacement@gmail.com

online: yangjian1886@hotmail.com (MSN)   yangjian1886 (Skype)