CSIR Central

DEVELOPMENT OF NEWER CEMENTITIOUS BINDER FROM LIME SLUDGE AND ITS USE IN MORTAR

IR@CBRI: CSIR-Central Building Research Institute, Roorkee


Field	Value

Creator	SINGH, AASTHA

Date	2017-07-31T04:39:19Z 2017-07-31T04:39:19Z 2017-07-31T04:39:19Z

Identifier	http://hdl.handle.net/123456789/1635

Description	Thesis submitted to AcSIR for the Award of the Degree of MASTER OF TECHNOLOGY in BUILDING ENGINEERING AND DISASTER MITIGATION The objective of the present work is to develop low Portland clinker cement using high proportion of aluminosilicate pozzolana aiming at to reduce global warming (CO2 emission). Various pozzolana such as fly ash, calcined clay and ground granulated blast furnace slag were selected for producing binder recipe. Alkaline lime sludge obtained from the paper industry was used as an alternative to limestone powder conventionally used for this purpose. The main approach is to dilute Portland cement with high volume of supplementary cementitious material in the presence of alkaline activator. Dilution of Portland cement content reduces the effectiveness of SCM activation unless an alkaline activator can be added. Consequently, the compatibility of the two cementitious gels, C-S-H (the main reaction product of the ordinary Portland cement) and N-A-S-H (the main product of the alkaline activation of aluminosilicate materials), may have important technological implications for future cementitious systems in which both products might be expected to precipitate. The lime sludge was thermo-chemically activated at 850oC in presence of sodium hydroxide to convert its crystalline state to non-crystalline state. The hydraulic properties of resulting sludge were evaluated as per IS: 1727-99 for use in Portland cement and its value obtained was ~4.2 MPa. Various recipes comprised of cement clinker, pozzolana (fly ash, calcined clay and ground granulated blast furnace slag) and thermo-chemically activated lime sludge were formulated by varying pozzolana as well as lime sludge proportions. The Blaine’s surface area and particle size distribution of the resulting mixes was found in the range of 500-626 m2/kg and 16.78 to 41.77 µm. It was concluded that, lime sludge based binder had more fineness than the Portland cement (285 m2/kg Blaine’s surface area). The lime absorption characteristic of these mixes was determined according to BS EN 196 (Part 5). All the mixes exhibited lime absorption value below the saturation line in lime solubility curve plotted between calcium oxide concentration and hydroxyl ion concentration showing their adequate pozzolanicity. The strength forming phases in the mixes were analyzed with the help of XRF, XRD, FTIR, SEMEDAX and TGA. The oxide composition indicated that CaO, SiO2 and Al2O3 content in the mix were in the range of 38-48 %, 26-32 % and 17-25 % respectively. The higher intensity of absorption bands in region 990 - 1120 cm-1 for lime sludge based binder over Portland cement indicated more reaction product formation which are related to strength development. The v existence of alite/ belite phase in the region 30-32o 2Ɵ of XRD supported strength development in hardened pastes. Needle and Prismatic type crystals as observed in FE-SEM were adequately viewed in the mix. Based on these results, it is concluded that cementitious binder containing GGBS/calcined clay and thermo-chemically activated lime sludge gives optimum results. Rheological studies of lime sludge based cementitious binders were carried out as a function of water-cement ratio, superplasticizer doses and lime sludge content. The mix followed Bingham fluid rule. Hysteresis loop between shear stress and shear rate of mix indicated its shear thickening behaviour. The workable mix (zero yield stress) was obtained at 0.2 % superplasticizer content. Hydration behaviour of various binders was studied with the help of isothermal conduction calorimetry by varying pozzolana and lime sludge proportion. It was observed that reduced induction period and increased height of acceleration peak indicated fast setting and more strength of lime sludge based binder compared to Portland cement. This is mainly attributed to formation of calcium carboaluminate hydrate, C3AH6 (the reaction between calcium aluminate hydrate and thermo-chemically activated lime sludge), C-A-S-H and other phases. The total heat (proportional to reaction products) of lime sludge binder was higher than the Portland cement. Adding activated lime sludge into mix resulted intense acceleration peak indicating the possibility of higher strength development than the Portland cement in the hardened pastes. Based on the results, it was found that lime sludge binder containing GGBS/calcined clay exhibited superior performance than those of Portland cement. The physical properties of developed thermo-chemically activated lime sludge binder (25%) were evaluated according to IS: 4031. The results were compared with the requirements of IS: 269. It was found that the developed binder satisfied the criteria laid down in the Standard. Life cycle analysis of lime sludge based binder was carried out using SIMA PRO software. It was observed that global warming in terms of CO2 emission was reduced by 51% when compared with the Portland cement. Abiotic depletion potential in terms of depletion of resources was reduced by 50% showing its sustainability over the Portland cement. It is concluded that thermo-chemically activated lime sludge based binder can be used as an alternative to Portland cement in many applications. The development of these kinds of hybrid cements based on low energy clinker and low lime mixes may encourage the utilization of unused lime sludge produced from various industries.

Language	en

Subject	Building Lime Lime Sludge Calcined Clay Ground granulated blast furnace slag Fly ash Limestone Gypsum Blended cement Materials Optimization of mixes X-ray diffractometer FE-SEM and EDAX M.Tech Thesis 2017 CSIR-CBRI

Title	DEVELOPMENT OF NEWER CEMENTITIOUS BINDER FROM LIME SLUDGE AND ITS USE IN MORTAR

Type	Thesis