CSA Cement Clinker

Introduction

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.



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 (%)
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 20ºC, using Vicat needle according to GB/T 1346-2001.
Mechanical strength at 20ºC, 95% relative humidity according to GB20472-2006 .
 
 Incorporation of Calcium Sulpho Aluminated Cement into a variety of mix designs, CSA Cement products
 exhibit a range of properties :
 •    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.

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