Cement Compounds

Rice husk lean-combustion in a bubbling and atmospheric fluidized bed reactor (FBR) of 0.3 m diameter with expansion to 0.4 m in the freeboard zone and 3 m height was investigated. Experiment design – response surface methodology (RSM) – is used to evaluate both excess air and normal fluidizing velocity influence (independent and controllable variables), in the combustion efficiency (carbon transformation), bed and freeboard temperature and silica content in the ashes. Hot gases emissions (CO2, CO and NOx), crystallographic structure and morphology of the ash are also shown. A cold fluidization study is also presented. The values implemented in the equipment operation, excess air in the range of 40–125% and normal fluidization velocities (0.13–0.15 Nm/s) show that the values near the lower limit, encourage bed temperatures around 750 °C with higher carbon transformation efficiencies around 98%. However, this condition deteriorated the amorphous potential of silica present in the ash...

Thermal activation of Ga’ara kaolin is used to produce a good quality metakaolin. Portland cement clinker is ground
and blended with 3% gypsum. In this study, two types of mixes are made: the first using 10% hydrated lime and
different percentages of metakaolin as replacement by weight of the blended cement; in the second type, only
metakaolin is used, without hydrated lime, in mixes as a replacement by weight of the blended cement. The aim of
this study is to make a new type of environmentally friendly, blended cement with good fresh and hardened
properties. Energy savings can be achieved by using materials produced as industrial by-products (metakaolin,
hydrated lime). The compressive strength is 42.1 MPa for the mix with 12% metakaolin and 0% hydrated lime, and
38.8 MPa for 12% metakaolin with 10% hydrated lime, as compared to the reference mix value of 37.9 MPa at age
90 d. Blended cement can be made with 86% Portland cement fineness, adding 22% metakaolin + hydrated lime as a
replacement by weight of the blend, to give almost the same compressive strength as the reference mix, with
excellent soundness properties. This could reduce the annual production of cement, as well as the associated
emission of gaseous pollutants from factories during the cement production process.

High Calcium Wood Ash (HCWA) and Pulverised Fuel Ash (PFA) are by-products from the wood biomass
and coal energy production which are produced in large quantity with combined annual production of 500
million tonnes. This poses a serious problem for disposal of the waste material especially at places where
land is scarce. The prescribed study was aimed to examine the mineralogical phases and their respective
amount present in the industrial wastes which governs the hydration mechanism towards self-sustained
solidification of the ashes when used in combination. Besides, the influence of various forming pressure and
hydrothermal treatment temperature on mechanical strength performance of HCWA-PFA cementless mortar
blocks was also examined. In the study, the mechanical strength of the HCWA-PFA cementless mortar
block produced using various forming pressure and hydrothermal treatment temperature was assessed in
terms of compressive strength and dynamic modulus. The results of the study are indicative that HCWA is
rich in calcium oxide and potassium oxide content. This enables the hybridization of HCWA with the
amorphous silica and alumina rich PFA to form a solid geopolymer binder matrix for fabrication of
cementless mortar block. Throughout the study, dimensionally and mechanically stable HCWA-PFA
geopolymer mortar blocks were successfully produced by press forming and hydrothermal treatment
method. Based on statistical analysis, the hydrothermal treatment temperature has a statistically
insignificant effect on the mechanical strength of the HCWA-PFA cementless mortar blocks. The dominant
factor which governs the mechanical strength of the HCWA-PFA cementless mortar blocks was found to be
the hydraulic forming pressure. Moreover, it was found that hybridized HCWA-PFA can be recycled as the
sole binder for fabrication of cementless concrete block which is a useful construction material.

authors/co authors : Cheah Chee Ban, Noor Shazea Ahmad Nordin, Part Wei Ken, Mahyuddin Ramli and Kwan Wai Hoe

The term cement is not new in construction niche as it is one of the oldest binding materials and the most popular construction materials used for construction such as residential buildings, skyscrapers, bridges, drainages, tunnels, pipelines, etc., good quality cement is therefore required for world-class infrastructure and low scale construction. Cement grade on the other hand indicates the compressive strength of cement that is measured in Mega Pascal (MPa) or N/mm 2. Cement is usually measured after 28 days of curing for a standard cube. It is very important for construction professionals to know the different classes of cement we have, and their suitability for different construction works as it directly relate to the strength of concrete used for construction. You may have heard about terms like grade 33, 43 or 53, these are terms used to describe the different grades of cement. In this article, we will strictly deal with the different grades of Ordinary Portland Cement (OPC) which is the most widely used cement in the world for producing concrete, mortar and non-specialty. The grades of Portland Limestone Cement (PLC) which is the most common type of cement in Nigeria will be extensively discussed in the subsequent article. There are three main classes or grades of OPC; 33 grade cement, 43 grade cement and 53 grade cement. Fig 1: Grades of OPC cement 33 GRADE ORDINARY PORTLAND CEMENT 33 grade cement refers to cement that has a mean compressive strength of 33N/mm 2 at the end of 28 days of curing standard mortar cubes. This grade is achieved when the mortars cubes are composed of one part of cement and three parts of standard sand (1:3 mix ratio). The initial setting time for this grade is greater than 75 minutes while its soundness is 10mm as per European Standards.

Rice husk lean-combustion in a bubbling and atmospheric fluidized bed reactor (FBR) of 0.3 m diameter with expansion to 0.4 m in the freeboard zone and 3 m height was investigated. Experiment design – response surface methodology (RSM) – is used to evaluate both excess air and normal fluidizing velocity influence (independent and controllable variables), in the combustion efficiency (carbon transformation), bed and freeboard temperature and silica content in the ashes. Hot gases emissions (CO2, CO and NOx), crystallographic structure and morphology of the ash are also shown. A cold fluidization study is also presented. The values implemented in the equipment operation, excess air in the range of 40–125% and normal fluidization velocities (0.13–0.15 Nm/s) show that the values near the lower limit, encourage bed temperatures around 750 °C with higher carbon transformation efficiencies around 98%. However, this condition deteriorated the amorphous potential of silica present in the ash. An opposite behavior was evidenced at the upper limit of the excess air. This thermochemical process in this type of reactor shows the technical feasibility to valorize RH producing hot gases and an amorphous siliceous raw material.

The fabrication of cement containing active mineral additives such as the natural Pozzolan presents a definite interest because of reduction of production costs and CO 2 emissions into the atmosphere. The present work focuses on the development of a new hydraulic cement binder by partially substituting the clinker for natural Pozzolan from the volcanic deposit of Difan-Amran in Yemen. The amount added varies with a step of 5 % within the range from 0 % to 40 %. The physical, chemical and mechanical analysis of the different formulations developed shows that the substitution of clinker for natural Pozzolan results in a new hydraulic binder of improved physical, chemical and mechanical properties. The increase of the additive content results in: (i) increase of the Blaine specific surface area facilitating the concrete hydration during the mixing; (ii) increase of the setting time of the paste augments; (iii) decrease of the density providing to prepare a relatively lightweight concrete; (iv) decrease of the mixing water quantity resulting in compressive strength increase. The production of the cementitious materials based on this new hydraulic binder minimizes the emission of CO 2 into the atmosphere on one hand, while on the other it decreases the energy consumption leading thus to production of less expensive construction materials.

Exterior building surfaces are exposed to considerable thermal stresses and UV radiations that significantly reduce their durability. Additionally, solar and thermal energy affect energy transfer through the building envelope that impacts indoor comfort and energy demands. Thus, improving the performance of exterior finish materials in regulating exterior surface temperatures would impact the overall performance of buildings. The aim of this research is to develop a responsive cementitious finish plaster for building façade applications to act as a filter for variable solar and thermal loads. The proposed cement plaster is combined with phase change materials (PCMs) and thermochromic (TC) pigments to control solar radiation and surface temperatures dynamically on the exterior façade. This paper presents the prototype development and optical characterization of the prototypes. The objective is to investigate the interaction between different PCM and TC pigments in regulating surface temperatures. Three different melting temperatures for the PCMs were tested in consideration of two different colours of the TC paint. Twelve samples were produced with 2.5% mass fraction of PCM and TC pigment each. The emissivity of the samples was measured using infrared thermography. The results showed that a high emissivity in high temperatures and a low emissivity in colder temperatures could be achieved.

The structure of the ettringite mineral was studied by means of FTIR spectroscopy and single crystal X-ray diffraction method. The experimental study was combined with the first principle calculations based on density functional theory (DFT) method. Predicted structural parameters (unit cell vectors and positions of heavy atoms) are in a very good agreement with the experimental data. Moreover, calculations also enabled to refine the positions of the hydrogen atoms not determined precisely by the single crystal X-ray measurement. The detailed analysis of the hydrogen bonds in the ettringite structure was performed and several groups of the hydrogen bonds were classified. It was found that the water molecules from the coordination sphere of Ca 2þ cations act as proton donors in moderate OeH$$$O hydrogen bonds with SO 2À 3 anions. Further, multiple OeH$$$O hydrogen bonds were identified among water molecules themselves. In addition, also hydroxyl groups from the [Al(OH) 6 ] 3À octahedral units are involved in the weak OeH$$$O hydrogen bonding with the water molecules. The calculated vibrational spectrum showed all typical features observed in the experimental FTIR spectrum. Moreover, performing the analysis of the calculated spectrum, all vibrational modes were distinguished and assigned. Such a complete analysis of the measured IR and/or Raman spectra is not fully possible, specifically for the region below 1500 cm À1 , which is characterized by a complex curve with many overlapped bands. A comparison of the vibrational spectra of ettringite and thaumasite (mineral structurally similar to ettringite) revealed the origin of the most important differences between them.

► SUMMARY:

♦ The Resilient Composite Systems (R.C.S.) could be counted as "The Methodically Reinforced Nonlinear Porous Materials", also having the high specific modulus of resilience in flexure. They are the compound materials, with some particular structural properties, in which, contrary to the basic geometrical assumption of the flexure theory in Solid Mechanics, the strain changes in the beam height during bending is typically "Nonlinear". The Resilient Composite Systems are made by expediently creating the disseminated suitable hollow pores and/or by distributing the appropriate lightweight aggregates throughout the methodically reinforced, fibered conjoined matrix so that; "the strain changes in the beam height during bending" is typically "nonlinear". Thereby, by applying the mentioned method to make the said composite systems, "considerably increasing the modulus of resilience and the bearing capacity in bending" together with "the significant decrease of the weight" and "the removal of the beam fracture possibility of primary compressive type" have been feasible. Through making these particular consistently functioning systems, the above-stated paradoxical virtues have been concomitantly fulfilled in "one functioning unit" altogether.

♦ The RCS (with the mentioned general structural properties and specific functional criteria) whose cement materials include the "C-S-H (Calcium Silicate hydrate) crystals" have been termed "Elastic Composite, Reinforced Lightweight Concrete (E.C.R.L.C.)".

♦ The RCS and ECRLC as a kind of RCS could be used in many cases. For instance, "Constructing Lightweightly and Consistently", also with practically utilizing the RCS and ECRLC in particular, can be counted as the pivotal and practical tactic to effectively increase the resistance & safety of the constructions against "earthquake" and lateral forces, in the large extent. For example, using some lightweight and insulating, "non-brittle", reinforced sandwich panels or 3D-panels, "with the high modulus of resilience and appropriate behavior against the bending loads and impacts", for construction could be taken into consideration according to the case... [It is worth remarking that; contrary to the ECRLC, the usual reinforced lightweight concretes, especially in the very low densities, are dramatically brittle; they do not have the appropriate behavior and resistance against the high bending loads and impacts.]
.
● "Resilient Composite Systems (RCS)":

♦ "Resilient Composite Systems" (RCS) are the compound materials, having some particular structural properties, in which, contrary to the basic geometrical assumption of the flexure theory in Solid Mechanics, the strain changes in the beam height during bending is typically "Nonlinear". The RCS could be counted as "The Methodically Reinforced Nonlinear Porous Materials", also having the high specific modulus of resilience in flexure. (Elastic Composite, Reinforced Lightweight Concrete; ECRLC is a type of RCS with the mentioned specifics.)

♦ Generally, the Resilient Composite Systems comprise these components as the main, necessary elements:
• 1) Mesh (Lattice);
• 2) Fibers or strands;
• 3) Conjoined matrix, having the disseminated suitable pores and/or the disseminated appropriate lightweight aggregates beads or particles. [Here, the general term of "lightweight aggregate" has a broad meaning, also including the polymeric and non-polymeric beads or particles.]

♦ The Resilient Composite Systems are made by creating the disseminated suitable hollow pores and/or by distributing the appropriate lightweight aggregates throughout the reinforced, fibered conjoined matrix so that; "the strain changes in the beam height during bending" is typically "nonlinear". Thereby, by applying the mentioned method to make the said particular composite systems, "considerably increasing the modulus of resilience and the bearing capacity in bending" together with "the significant decrease of the weight" and "the removal of the beam fracture possibility of primary compressive type" have been feasible. Through making these particular consistently (unitedly, integratedly) functioning systems, the stated paradoxical virtues have been concomitantly fulfilled in one functioning unit altogether.

♦ Generally, in these consistently functioning units, the amount and the use manner of the mentioned components in the organized system are so that; the reciprocal interactions among the components finally lead to the "typically nonlinear strain changes in the beam height during bending" (as the "basic functional character" of these systems with the specific testable criteria and indices) and the functional specifications fulfillment of the system.

♦ In the RCS in general, the main strategy to raise the modulus of resilience in bending is "increasing the strain capability of the system in bending" within the elastic limit.

♦ Here, the main tactic to realize the stated strategy is: "creating the suitable hollow pores and/or using the appropriate lightweight aggregates, all disseminated throughout the methodically reinforced conjoined matrix", to provide the possibility for occurring of the expedient internal deformities in the matrix during the bending course, which could lead to the more appropriate distribution of the stresses and the strains throughout the system and the more strain capability of the beam in flexure. On the other hand, only creating the hollow pores and/or using the lightweight aggregates in the matrix, by itself, not only cannot lead to the mentioned goals but also brings about weakening of the matrix and its fragility. Hence, concomitantly, the matrix should be well supported and strengthened. Here, this essentially ameliorating and strengthening the matrix are performed by giving attention to "the internal consistency of the matrix" and also via "employing the expedient reinforcements in two complementary levels": 1) Using the fibers to the better distribution of the tensile stresses and strains in the matrix, and to increase the matrix endurance and the modulus of resilience in tension and bending; 2) Using the mesh or lattice to better distribution of the tensile stresses and strains in the system, and to increase the system endurance and the modulus of resilience in tension and bending.

♦ In these systems, the presence of the mentioned hollow pores and/or lightweight aggregates disseminated throughout the conjoined matrix (which has been ameliorated through making "an integrated, reticular structure") provides the possibility for occurring of the expedient internal deformities in the matrix during the bending course. By the way, this can lead to the less accumulation of the internal stresses in the certain points of the matrix during bending, the better absorption and control of the stresses, and providing the more strain capability of the beam, especially within the elastic limit.

♦ The occurrence of the remarked internal deformities in the said methodically reinforced matrix during the bending course also means; the occurrence of the deformities in the said hollow pores and/or lightweight aggregates well disseminated throughout the conjoined matrix, in two different forms. Indeed, we have the internal deformities in the fibered lightweight matrix of the system throughout the bending course, in two main different forms, leading to: A) The comparative increase of the thickness (height) of the in-compressing layers (particularly in the upper parts of the beam) and the conversion of some internal compressive stresses to the internal tensile stresses (on the axis perpendicular to the mentioned internal compressive tensions) in the in-compressing layers; B) The comparative decrease of the thickness (height) of the in-tension layers (particularly in the lower parts of the beam) and the conversion of some internal tensile stresses to the internal compressive stresses (on the axis perpendicular to the mentioned internal tensile tensions) in the in-tension layers.

♦ In the under-bending sections of the "Resilient Composite Systems", the deformities occurring in the "conjoined layers perpendicular to the applied load direction" during the bending course are so that; "the initially plane sections perpendicular to the beam axis" typically shift from "the plane status" to "the curve status" during the bending course. Thereby, the basic geometrical assumption of the flexure theory in Solid Mechanics ("linearly" being of the strain changes in the beam height during bending) and the respective trigonometric equations & equalities are mainly overshadowed in these systems.

♦ This way, through occurring of the remarked internal deformities in the strengthened matrix during the flexure course, the stresses are more distributed and absorbed, and the rise rate of the internal stresses in the matrix ... reduces.  ...
●●●
► [sites.google.com/site/newstructure1]

The fabrication of cement containing active mineral additives such as the natural Pozzolan presents a definite interest because of reduction of production costs and CO 2 emissions into the atmosphere. The present work focuses on the development of a new hydraulic cement binder by partially substituting the clinker for natural Pozzolan from the volcanic deposit of Difan-Amran in Yemen. The amount added varies with a step of 5 % within the range from 0 % to 40 %. The physical, chemical and mechanical analysis of the different formulations developed shows that the substitution of clinker for natural Pozzolan results in a new hydraulic binder of improved physical, chemical and mechanical properties. The increase of the additive content results in: (i) increase of the Blaine specific surface area facilitating the concrete hydration during the mixing; (ii) increase of the setting time of the paste augments; (iii) decrease of the density providing to prepare a relatively lightweight concre...

Alkali activated cements have recently become an alternative to Portland cement (PC); however, the use of strong alkaline solutions involves safety issues. Natural pozzolans such as volcanic pumice (VP) have been used as partial replacement to PC, in contents lower than 25% as higher contents reduce strength. No reports were found on the use of VP as precursors in hybrid cements, as those described in this research. An experimental design based on the Response Surface Methodology (RSM) was used to explore paste formulations with high VP contents and cured at 20°C; the experimental factors were the VP-PC ratio at 75:25 to 25:75, the %Na2SO4 (NS) at 4 to 12% and Ca(OH)2 (CH) in molar ratios NS/CH from 0.5 to 1.25. The binders with 25% and 50% VP had 28-day compressive strengths between 31 and 43 MPa after dry curing; higher VP contents reduced the strength. The activators had a positive effect strength wise, although the higher Na2SO4 not always was the most effective. XRD, SEM and IR indicated the formation of hydration products of C-S-H and ettringite; which promoted strength and relatively strong microstructures. The VP particles reacted by a mechanism of dissolution and precipitation and the cements had hydraulic behavior and the strength shows a trend to increase with time.

To contribute the minimization of emissions of greenhouse gas (GHG) into the atmosphere which occurs during the production of cement and to improve the physical properties and mechanical performance of mortars and/or concrete, we have incorporated a mineral addition
which is the limestone fillers (F-Lime) in their formulation matrix. While partially substituting the clinker by this one at various percentages ranging from 5% to 40% by weight of cement with a step of 5% in presence of a superplasticizer. The influence of the incorporation of F-Lime on the physical properties (fineness by specific surface Blaine /density/setting of initial and final time/water content) was studied on one hand. The effect of the addition of F-Lime on the mechanical performance (compressive strength/porosity/capillary absorption) was evaluated on the other hand. The obtained results by different formulations prospected showed that the addition of F-Lime in the formulation matrix of a cementitious material increases the fineness.
Moreover, its density was decreased. We observed that the setting time increases with the percentage of F-Lime was increased. Similarly, the compressive strengths at a young age (2 days), median age (7 days) and long-term (28 days) were improved. The W/C report, the porosity, and the capillary absorption have been decreased. These results show that we have succeeded to produce an ecological and durable cementitious material.

Cement factories are found to be one of the major causes of pollution. Cement mist and dusts depositions affect the photosynthesis, secretion and fertility of the plant. Increasing the concentration of airborne dust reduces photosynthetic potential in leaves, closes leaf stomatals and, in general, reduces the growth and fertility of plants. The purpose of this study is to determine the best tree species for absorbing contaminants from the cement plant. Data were analyzed using descriptive statistics and inferential statistics. To determine the normal distribution of metal content in oak, Paliurusspina-christi Phragmitesaustralis, Kolmogorov-Smirnov test was used and one-way analysis of variance was used to determine the difference. The results showed that F calculated for cadmium level (F = 4.123) with degrees of freedom df = 17 and df = 2 at 95% confidence level (α = 0.05) is greater than F from critical table (F = 3.59), therefore difference between cadmium and oak and Paliurusspina-christi and Phragmitesaustralis plants is statistically significant, but the means of other metals in oak and Paliurusspina-christiandPhragmitesaustralisis statistically equal. Also, the amount of cadmium with oak tree was significantly different (P-value = 0.049). It was found that the cadmium content of the Paliurusspina-christi was higher than the oak tree, in other words Paliurusspina-christicadmium others get better.

Drying cement-based materials is a necessary step to characterize the microstructure by microscopy, adsorption, or mercury intrusion. The isopropanol (IPA) exchange method is commonly used to replace the pore solution prior to drying, as it reduces the capillary pressure and thereby helps to preserve the microstructure of the hydrated cementitious materials. However, some physical and chemical effects of IPA on hydration products have been reported. These effects cannot be completely avoided, but can be reduced by shortening the exchange duration, in particular for effects on ettringite. This study carried out experiments with different exchange durations and IPA removal techniques to address research gaps in the literature. For 1-mm cubes of cement paste with IPA diffusion coefficient of 1 × 10 − 11 m 2 /s, the compared exchange durations are 5 min, 15 min (value from the literature), 40 min (when the mixture at the sample center achieves 95% of the drop in surface tension from water to IPA), 80 min (when the IPA/water mixture at the sample center reaches an azeotrope), 5 h (when over 99% IPA is replaced at the sample center), and 24 h (prolonged exchange). After IPA exchange, samples were either directly dried at 40 • C with flushing N 2 or washed by diethyl ether prior to N 2 drying. Even though the exchange duration of 40 and 80 min, in theory, can reduce the damage from capillary pressure, the nitrogen adsorption results do not show any advantage in preventing microstructural alteration. The 5-h exchange provided results similar to the 24-h exchange, but the latter induced slightly more serious chemical effects resulting from the longer contact of IPA with hydration products. In addition, the compared IPA removal techniques do not show significant differences. Therefore, this study suggests using small samples (~1 mm) for microstructural studies following IPA exchange for a period corresponding to the time when 99% of the water (mole fraction) at the sample center is replaced.

Essential focus of the study has been to acquire thermoanalytical events, incl. enthalpies of decompositions-∆H, of natural minerals of calcium-silicate-sulfate-aluminate hydrates. The thermoanalytical curves of thaumasite and ettringite are fully in line with that reported in reference sources. The values of ∆H calculated from DSC curves in the intervals of key decomposition steps ranging from 50 to 250 °C, achieve (1215 ± 60) J g-1 for thaumasite and (930 ± 40) J g-1 for ettringite. The differing values of decomposition enthalpies ∆H, as presented by various research groups, are indicated and critically discussed in the paper.

The aim of the present work is to valorize a local and natural sources, such as the natural Pozzolan (PN) and the pure limestone (P,Lime) of the region of Amran Yemen in using them in the production of cement and concrete to reduce the energy and raw material consumed in a first time and minimize the emission of the greenhouse gases (GHGS). Therefore, in this work we have studied the influence of mineral additions in PN and P,Lime in cement, partially substituting the clinker by these materials in powder form and fine crushed, while fixing the total addition at 40% of the addition which make up the mixture in PN and P,Lime. The variation of the percentage was fixed at 5% to lead the following formulations: F1(0% PN + 0% P,Lime), F2(40% PN + 0% P,Lime), F3(35% PN + 5% P,Lime), F4(30% PN + 10% P,Lime), F5(25% PN + 15% P,Lime), F6(20% PN + 20% P,Lime), F7(15% PN + 15% P,Lime), F8(10% PN + 30% P,Lime), F9(5% PN + 35% P,Lime), and F10(0% PN + 40% P,Lime) in weight of clinker. The physica...

The alkali-activated slag (AAS) cement is an interesting building material, confronting to the new economical and ecological challenges. In order to enhance its physical properties in comparison with ordinary Portland cement (OPC), we used natural pozzolana as a mineral addition. The parameters studied are: the fineness of the addition (5350 and 5650 cm2/g), and its percentage (0 to 30%). The activator used is NaOH (5M) and the curing temperature was fixed at 20°C. The results show the possibility to obtain compound alkali-activated slag cement with better stability and a compressive strength higher than 35 MPa.

Though Indian cements boast of higher power & heat efficiencies their waste management in terms of fly ash utilization, carbon capture is un-sustainable going by the current rate of  fly-ash utilization as against the 100% utilization prescribed by Government of India. There has been a positive wave of changes across the Indian Cement Industry, significantly on the front of Cement economics and Sustainability with a number of successful studies have been conducted on the use of Nano-Silica in cement-concrete, but the cement industry still faces a broad range of challenges from the ‘nano’ materials in issues of cost, mixing, dosage, compatibility etc. As existing literatures suggest, nano-materials did exist historically but people were ignorant of such science due to the nonexistence of highly sophisticated instruments and today with nano-enabled TiO2 cements, other countries’ cements have gone from ‘low carbon’ to ‘carbon neutral’ to ‘carbon positive’ on the lines of ‘polluter to pay’ principles which we need to focus upon. Also, Fly ash, a coal combustion product, primarily generated from the thermal power plants and originally considered a hazardous waste, which was previously normally discarded into the atmosphere, now requires that it be captured prior to release, as per new pollution norms. Looking at the future projections of fly ash generation it is expected that, coal will continue to be the fuel of choice and in spite of the massive initiatives taken by the government , there will be continued dependence on high ash coal to meet the future targets of power generation  to achieve the objective of ‘power to all'.
As of now, there is not much literature available regarding the compatibility of these two materials i.e. nano-materials with fly ash. Our paper reports that with small addition of nano particles viz.  Nano-Silica (nS) in optimized quantities (w.r.to the weight of cement & water added as per the normal standard consistency formula of the Indian standards) to Portland Pozzolona Cement (PPC) it is observed that the consistency in gain of strength at 28 has been retained in the long term of 365 days, showing a strength of more than 55% increase over that of control PPC.  Thus this Paper aims to explore the fact that fly-ash based cement containing 15%-35% fly-ash (as per Test Certificate), like Portland Pozzolona cement (PPC) have arrested this long term inconsistency to a certain appreciable extent due to addition of Nano-silica by its pozzolanic activity, finely divided spherical form i.e. high surface area and higher residual carbon content measured by loss on ignition (LOI), when compared to OPC.
So Nano’s blend, if it can take off then perhaps we would be leap-frogging into a 2 world if not 1.5.

Abstract
Polymer plaster forms part of a group of spray on products that use polymers to supplement or replace cement as a binder in grout systems. The types include but are not limited to polymer plasters, polymer-impregnated concrete, polymer concrete, and polymer-Portland-cement concrete.

Polymer plaster and concrete has historically not been widely adopted due to the high costs and difficulty associated with traditional manufacturing techniques. However, recent progress has led to significant reductions in cost, meaning that the use of polymer plaster and concrete is gradually becoming more widespread.

This paper will focus on addressing these particular questions:
.
• What are polymers?
• Are polymers a dangerous OHS additive?
• Why polymers should be considered in plaster & concretes underground
• Examples of polymer modified products and their applications

Carbonates are primary minerals of the carbonatites and kamafugites sourced from Toro-Ankole geological region of the East African Rift system. Consequently, these materials are silica undersaturated. They are currently utilized as mineral additions in production of Portland pozzolana cements in Uganda. No published work exists to show how their unique composition might affect their pozzolanic performance and other concrete properties. This study investigated the effect of the carbonate minerals in the natural pozzolans and calcination on setting time, standard consistency, workability, soundness, early heat of hydration and strength development of blended cements. Two (2) samples, a carbonatite and a kamafugite sourced from deposits located in the Toro-Ankole geological region of the East African rift system were calcined in a furnace at 825 °C for one hour. The samples were then subjected to XRD analysis for mineralogical composition characterisation and to establish the effect of calcination at 825 °C on mineralogy. Setting time, standard consistency, workability, soundness and strength development were studied following standard procedures for testing blended Portland cements. Calcination led to a gain in compressive strength for both test pozzolans, the kamafugites showing a higher gain in strength than the carbonatite. The higher gain in pozzolanic performance for the kamafugites is likely due to kaolinite, a secondary mineral in the test pozzolan whose pozzolanic reactivity is activated by thermal destabilization. Calcination also led to pacification of the early age properties of cements blended with test carbonatites and kamafugites. The study reveals the carbonate minerals in the test pozzolans as a considered factor in accelerating early hydration of Portland cement. Hydration progression of Portland cement controls the important properties of fresh concrete (workability, setting and paste microstructure), which in turn directly impacts on the strength and durability properties of hardened concrete. Cements blended with carbonate bearing natural pozzolans therefore present interesting perspectives on how paste microstructure composition and durability performance properties might be impacted.

In this work new material, durable cement based on the different percentages of pure limestone (P,Lime) and super plasticizer has been developed, partially substituting the clinker by this material in finely ground powder form. The influence of the incorporation of P,Lime on the physical chemical characteristics of cement (finesse by specific surface Blaine and density), on the physical properties of the cement paste (setting time and water content) and on the mechanical performance (compressive strength) of mortar and/or concrete to hardened State has been evaluated. The obtained results by different methods of physical, chemical analysis showed that, the adding of P. Lime in cement increases the fineness. In more its density is decreased. We observed that, the setting time increases in function on the addition of P,Lime in the cement matrix. Similarly, the mechanical resistance to compression at a young age (2 days), median age (7 days) and long term (28 days) improve as a functio...

Thermal activation of Ga'ara kaolin is used to produce a good quality metakaolin. Portland cement clinker is ground and blended with 3% gypsum. In this study, two types of mixes are made: the first using 10% hydrated lime and different percentages of metakaolin as replacement by weight of the blended cement; in the second type, only metakaolin is used, without hydrated lime, in mixes as a replacement by weight of the blended cement. The aim of this study is to make a new type of environmentally friendly, blended cement with good fresh and hardened properties. Energy savings can be achieved by using materials produced as industrial by-products (metakaolin, hydrated lime). The compressive strength is 42·1 MPa for the mix with 12% metakaolin and 0% hydrated lime, and 38·8 MPa for 12% metakaolin with 10% hydrated lime, as compared to the reference mix value of 37·9 MPa at age 90 d. Blended cement can be made with 86% Portland cement fineness, adding 22% metakaolin + hydrated lime as...

The aim of this work is to determine by the experimental design of response surface methodology a model which predicts the compressive strength as a function of the proportion of the constituents of a new hydraulic binder based on a combination of different percentages of Natural pozzolana (PN) and pure limestone ( P,Lime). A second-degree
the polynomial model was therefore used to model the influence of three key parameters which are the water content, the proportion of natural pozzolan and the proportion of pure limestone, related to the  ompressive strength at 28 days, which represents the model of
rupture, while the other components and the operating condition were kept fixed. Our study has three essential phases: in the first phase, the objective is to determine the main physical, chemical, and mechanical characteristics of the materials used, the choice of the method of
formulation and the realization of the different mixes. The second phase, which aims to analyze the effects and interactions between the various factors expected, to predict the most influential factor in response on one hand and to highlight it on the correlations and their interactions on the other hand. As for the last phase, it consists of the search for the optimum which is done by the response surface methodology of experimental design of each factor studied and the validation of the model retained.

The aim of the present work is to valorize a local and natural sources, such as the natural Pozzolan (PN) and the pure limestone (P,Lime) of the region of Amran - Yemen in using them in the production of cement and concrete to reduce the energy and raw material consumed in a first time and minimize the emission of the greenhouse gases (GHGS). Therefore, in this work we have studied the influence of mineral additions in PN and P,Lime in cement, partially substituting the clinker by these materials in powder form and fine crushed, while fixing the total addition at 40% of the addition which make up the mixture in PN and P,Lime. The variation of the percentage was fixed at 5% to lead the following formulations: F1(0% PN + 0% P,Lime), F2(40% PN + 0% P,Lime), F3(35% PN + 5% P,Lime), F4(30% PN + 10% P,Lime), F5(25% PN + 15% P,Lime), F6(20% PN + 20% P,Lime), F7(15% PN + 15% P,Lime), F8(10% PN + 30% P,Lime), F9(5% PN + 35% P,Lime), and F10(0% PN + 40% P,Lime) in weight of clinker. The physical-chemical properties of the new formulations of cement based to PN and P,Lime, to know (the fineness by Blaine specific surface area, the density, the loss on ignition), the physical properties of fresh cement paste, such as (the setting time, the content water) and the mechanical strength of the mortar and/or concrete were studied. The obtained results by the different methods of physical-chemical analyses such as (XRF / XRD / calcination in the air, the absolute density, the fineness by the air permeability), physical properties (the Vicat of water content and setting time) and the mechanical properties of the different formulations show that there was an improvement in the fineness, the setting time and mechanical properties.