Comparative Study of Metakaolin and Zeolite Tuff Influence on Properties of High-Strength Concrete

Composite admixtures which include active pozzolanic components and high-range water reducers, allows to obtain high-strength, particularly dense and durable concrete to achieve a reduction in resources and energy consumption of manufacturing.Zeolite, containing a significant amount of active silica, can serve as one of the alternative substances to resources and energy consuming mineral admixtures like metakaolin and silica fume. The deposits of zeolites are developed in Transcarpathia (Ukraine), USA, Japan, New Zealand, Iceland and other countries. It is known that zeolite tuffs exhibit pozzolanic properties and are capable to substitution reactions with calcium hydroxide.However, the high dispersion of zeolite rocks leads to a significant increase in the water consumption of concrete. Simultaneous introduction of zeolite tuffs with superplasticizers, which significantly reduce the water content, creates the preconditions for their effective use in high-strength concrete.Along with dehydrated (calcined) zeolite, natural (non-calcined) zeolite expresses itself as an effective mineral admixture of concrete. When using non-calcined zeolite, the effect of increasing in compressive strength at the age of 3 and 7 days is close to the effect obtained when using dehydrated zeolite: 8-10% and 10- 12%, respectively, and 28 days the strength growth is 13-22%. The use of non-calcined zeolite has a significant economic feasibility, so it certainly deserves attention. There were compared the effect of zeolite to metakaolinThe results of the research indicate that the use of composite admixtures, consisted of calcined (non-calcined) zeolite tuff of high dispersity and superplasticizer of naphthalene formaldehyde type, allows to obtain concretes classes C50…C65.

Effect of Using Ground Granulated Blast Furnace Slag in Rigid Pavement Overlays

Cement is replaced with Ground Granulated Blast Furnace Slag (GGBS), to produce a cost effective concrete and to gain effective compressive strength. It is produced in iron manufacturing industries. It has pozzolanic properties and has particle size less than 90μ. In this experimental study, cubes of size 150×150×150 mm and cylinders of 150 mm dia and 300 mm height were casted byreplacing GGBS from dosage of 8% up to 65% for curing period of 7days, 14days, 28days and 56days for M 40 grade concrete. Also, Alccofines were added in addition in varying percentage of 3%, 6%, 9% and 12% in order to gain high early strength and increase the workability. Hyper-Plasticizers were also added in order to reduce the water-content of the concrete. The results of GGBSCC were compared with that of normal concrete results.

Natural Fluorite from Órgiva Deposit (Spain). A Study of Its Pozzolanic and Mechanical Properties

This work presents the results of the partial substitution of Portland cement (PC) by natural fluorite (NF) and calcined fluorite (CF) in mortars, at 10%, 25% and 40%. To meet these objectives, a sample of fluorite was initially studied by XRD, SEM and Raman Spectroscopy (RS). A chemical quality analysis (CQA) and a chemical pozzolanicity test (CPT) at 8 and 15 days were carried out in a second stage to establish the pozzolanic properties of the investigated sample. Finally, a mechanical compressive strength test (MCST) at 7, 28 and 90 days was carried out on specimens made up with PC/NF and PC/CF mixes, at a ratio of 10%, 25% and 40%. XRD, SEM and RS results indicated fluorite as the major mineralogical phase. The CPT and CQA showed an increase in the pozzolanicity of the samples from 8 to 15 days. The MCST showed an increase in compressive strength from 7 to 90 days for both PC/NF and PC/CF specimens. The results obtained establish that fluorite produces positive effects in the mortar and contributes to the gain of mechanical strength over time, being a suitable material for the manufacture of cements with pozzolanic addition with a reduction of CO2 emissions, and by reducing the energy costs of production.

The Compressive Strength and Water Absorption of Railway’s Concrete Sleepers Containing Palm Oil Fuel Ash (POFA) as a Cement Replacement Material

Railway’s concrete sleepers demand high consumption of cement which generates higher energy assumption and carbon emission. Meanwhile, in Malaysia, around 100 tonnes of palm oil fuel ash (POFA) were disposed of in the landfill, which endangering environmental health. However, this POFA have pozzolanic properties that can be employed as cementitious material. Therefore, this study aimed to produce a sustainable concrete sleeper by using POFA as a cement replacement material focusing on the compressive strength and water absorption performance. Concrete samples with a strength grade of 55MPa and w/c of 0.35 were prepared with three design mixes containing 0% (control), 20%(POFA20), and 40%(POFA40) of POFA. For the compressive strength test, a compression machine was used. Meanwhile, the water absorption was measured at atmospheric pressure. Both tests were conducted at 7 and 28 days of curing age. The results show that as the curing age increases, their water absorption and compressive strength improves, indicating a pozzolanic reaction. In terms of POFA content, the water absorption increases by 14% and 54% for POFA20 and POFA40, respectively. Meanwhile, the compressive strength reduced by 39% for POFA20 and 67% for POFA40. Since POFA20 meets the standards, it is however applicable in slab tracks.

Optimization of recycled polyethylene terephthalate plastic bottle fibers in grasscrete

Cement and concrete production account for between 5% to 8% of global CO2. Waste PET plastic and glass waste have also brought about rapid environmental degradation. Glasscrete was developed with glass powder of fewer than 75 microns (has pozzolanic properties) that performed 14% better than concrete at 90 days. So, to further this effort, this experimental research considered the glass create C20 (at 10% cement replacement) and added PET fibers (of aspect ratio 25) at different percentages of 1%, 2%, 3%, and 4% the weight of cement in a bid to optimize the grasscrete performance and its ability to absorb PET waste. Glasscrete being extremely brittle alone, failed by cracking at all percentage PET additions, thus improving its safety factor. A 1% PET fiber addition to grasscrete exhibited the highest strength properties compared to other percentage additions while having a durability of 1.5% better than concrete. It is thus recommended for structural uses as it outperforms concrete. Despite this, a 1% fiber addition decreased grasscrete’s compressive strength by at least 3.5% at 28 days and 6% at 90 days but improved the flexural strength by 5.4% at 28 days and 0.8% at 90 days testing.

Mechanical Performance and Acid Resistance of Self Compacting Concrete with Fly Ash and Rice Husk Ash as Cementitious Materials

Self-compacting concrete (SCC) is an extremely flowable, non-segregating concrete that fills every corner of formwork evenly and completely by its own mass and encapsulates reinforcement without vibrating, all while retaining homogeneity. SSC’s mechanical efficiency can be enhanced by using byproducts or waste materials as cement replacements. Rice husk ash (RHA) & fly ash stay very reactive byproducts. Because of its high silica content, Fly ash and RHA have strong pozzolanic properties, used as complementary cementations material in SSC. The automatic properties and Self-compacting concrete has a high acid resistance determined. Mainly the cement is replace by fly ash & rice husk ash with three different percentages variations (10%, 20%, and 30%). In each percentage of replacement, the fly ash and RHA has equal percentages. For example, in 10% of replacement 5% of fly ash and 5% of RHA is replaced. In frequently fly ash is industrial by-product and having the pozzolanic properties. And the RHA (rice husk ash) is also a pozzolanic reactive material. Compared to the adhesive, fly ash & RHA has more silica ingredient. The self-compacting concrete was calculated for M30, and specimens are cast. Compressive strength and split tensile strength, flexural strength, and durability (acid resistance) tests are performed for 7 days, 14 days, and 28 days.

Altered Volcanic Tuffs from Los Frailes Caldera. A Study of Their Pozzolanic Properties

This work presents the results of the study of the physical, chemical, mineralogical and pozzolanic properties of the altered volcanic tuffs (AVT) that lie in the Los Frailes caldera, south of the Iberian Peninsula, and demonstrates their qualities as pozzolans for the manufacturing of mortars and pozzolanic cements of high mechanical strength. The main objective of this research is to show to what extent the AVTs can replace portland cement (PC) in mortars, with standardised proportions of 75:25% and 70:30% (PC-AVT). To achieve these objectives, three AVT samples were studied by a petrographic analysis of thin section (PATS), DRX, FRX and MEB. The pozzolanic properties were determined by three methods: electrical conductivity (ECT), chemical pozzolanicity tests (CPT) at 8 and 15 days and mechanical strength tests (MS) of the specimens at 2, 7, 28 and 90 days. Studies of a PATS, DRX, FRX and MEB showed that the AVT samples’ constitutions are complex where smectite (montmorillonite), mordenite, quartz, halloysite, illite, kaolinite, volcanic glass and lithic fragments coexist. The results of the ECT and CPT tests confirmed the pozzolanic properties of the samples analysed and proved an increase in mechanical strength from 2 to 90 days of testing.

Application of Concretes Made with Glass Powder Binder at High Replacement Rates

Glass is a material that can be reused, except for a small part that, due to its residual characteristics, cannot be reused and becomes a nonbiodegradable waste to accumulate in landfills. The chemical composition and pozzolanic properties of waste glass are encouraging for the use of these wastes in the cement and concrete industries and for providing technically and environmentally viable solutions. In this study, we propose the production of deactivated concretes with a high content of glass powder in the binder. The substitution percentage of glass powder for cement used in this work was between 70% and 80%. Consistency, air content, bulk density, workability, compression strength, and permeability tests were performed. Regarding compressive strength, the results obtained at 90 days for percentages of cement substitution by glass powder of 70 and 80%, respectively, were 14.2 and 8.6. The chemical analysis of leachates showed concentrations of Fe, Cu, V, Ni, and Mo, in mg L−1, of 1.57, 1.38, 0.85, 0.95, and 0.44, respectively. The results obtained, compared with the relevant legislation, have proved that the inclusion of glass powder in a high percentage of substitution and with a granulometry of 20 µm in the manufacture of deactivated concretes is feasible for exterior pavements.

A review of the Effect of Calcination Temperature on the Properties of Calcined Clay Concrete

Naturally occurring clays can produce an amorphous siliceous material possessing pozzolanic properties if is heated at an appropriate temperature. Calcination at the right temperature is crucial since it affects the formation of relevant phases, pozzolanic reactivity, hydration kinetics and consequently, increase the strength and durability of concrete. This paper reviews the effect of calcination temperature on the properties of mortar and concrete corporating calcined clay as partial cement replacement. It is observed that calcination temperatures close to 900°C decrease the specific surface and represent the onset for the structural reorganization of aluminosilicates. Both factors limit the pozzolanic reactivity and can consequently compromise compressive strength. The results show that mortar containing 20% calcined clay obtained compressive strength of 63MPa when calcined at 800oC, surpassing the reference cement by about 8MPa.

Reactivity of Ground Coal Bottom Ash to Be Used in Portland Cement

Ground coal bottom ash is considered a novel material when used in common cement production as a blended cement. This new application must be evaluated by means of the study of its pozzolanic properties. Coal bottom ash, in some countries, is being used as a replacement for natural sand, but in some others, it is disposed of in a landfill, leading thus to environmental problems. The pozzolanic properties of ground coal bottom ash and coal fly ash cements were investigated in order to assess their pozzolanic performance. Proportions of coal fly ash and ground coal bottom ash in the mixes were 100:0, 90:10, 80:20, 50:50, 0:100. Next, multicomponent cements were formulated using 10%, 25% or 35% of ashes. In general, the pozzolanic performance of the ground coal bottom ash is quite similar to that of the coal fly ash. As expected, the pozzolanic reaction of both of them proceeds slowly at early ages, but the reaction rate increases over time. Ground coal bottom ash is a promising novel material with pozzolanic properties which are comparable to that of coal fly ashes. Then, coal bottom ash subjected to an adequate mechanical grinding is suitable to be used to produce common coal-ash cements.