Manufacture Of Mortars Research Articles

ANÁLISIS DE LA VIABILIDAD TÉCNICA Y MEDIOAMBIENTAL DE LOS MORTEROS DE CEMENTO ELABORADOS CON ÁRIDO RECICLADO MIXTO

The construction industry is one of the main economic drivers of nations, but it is also an industry that generate a large amount of waste that cause a strong negative environmental impact. This research studies the effect of partial or total substitution of natural aggregate by mixed recycled aggregate in the manufacture of cement mortars. To this end, an experimental study was carried out to examine the mechanical properties and evaluate the shrinkage of mortars made with different proportions of mixed recycled aggregate, to subsequently improve these properties by adding reinforcement fibres to the mortars. The results show how from 50% replacement of natural aggregate the technical performance of the mortars is affected, and how basalt fibre is postulated as a suitable reinforcement for these construction materials. In addition, the carbon footprint derived from the manufacturing process of the mixed recycled aggregate has been determined, which is lower than that obtained for natural aggregate.

The Effect of Acanthocardia tuberculata Shell Powder as Filler on the Performance of Self-Compacting Mortar.

In this research, the feasibility of using Acanthocardia tuberculata shell waste from the canning industry in the manufacturing of self-compacting mortar (SCM) was tested. The seashells were finely ground to be used as filler instead of the limestone filler normally used in this type of SCM. First, a physicochemical and microstructural characterisation of all raw materials was carried out, including the particle size distribution of both fillers. Subsequently, the self-compactability properties in the fresh state of SCM were evaluated using a total substitution by volume of limestone filler for seashell powder, using different self-compactiblity parameters. The mineralogical phases of all the SCM tested were identified once hardened by means of X-ray diffraction technique, thermogravimetric and differential thermal analysis. In addition, the mechanical properties, water absorption capacity, dry bulk density and accessible porosity of water of hardened mortars at 28 days of curing were analysed. The effect of replacing limestone filler by Acanthocardia tuberculata filler resulted in a decrease in compressive strength of 29.43, 16.84 and 2.29%, respectively. The results indicate that it is possible to completely replace natural limestone filler with Acanthocardia tuberculata shell filler without significantly affecting the mechanical properties of SCM.

Tinjauan Kuat Tekan Dan Absorbsi Mortar Yang Mengandung Air Garam

Mortar is a building material that serves to glue bricks, bricks, plaster, and so on. As an adhesive, mortar has a viscosity that is useful in determining compressive strength. In the manufacture of mortar, SNI 03-6882-2002 requires the use of clean fresh water, but in reality, as an archipelagic country, some of the islands in Indonesia are isolated from fresh water. As a result, freshwater becomes an expensive item, because it is imported from other areas, so it requires transportation costs. If the mortar is required to use water according to SNI standards, the project implementation costs will be expensive. In areas that do not have adequate fresh water, mortar is made using water obtained on-site, including brackish, salt, and sea water. Seawater contains elements of NaCl salts which can bind Calcium Hydroxide (CaOH) compounds, reducing the CaOH compounds in the mortar will increase the compressive strength of the mortar. In this study, a review of brine as a mixture of mortar materials was carried out with the aim of knowing the performance of mortar containing salt water by compressive strength test and Absorption test. The amount of salt water added to the mortar mixture is 0%; 0.5%; 1%; 1.5%; 2%; 2.5% ; 3%; 3.5% of the volume of water used as a mortar mix. Cube test object measuring 50x50x50 mm3 in the amount of 5 in each treatment, made from a mixture of 1PC: 2.75 Sand (based on weight ratio), with a water-cement factor (FAS) of 0.45. The test results obtained the compressive strength value of the mortar with the addition of salt water can reduce the compressive strength value but the use of brine with a content of 3.5% is still in the category of minimum permissible pressure according to SNI03-6882-2002. While the absorption value of the mortar can increase fiber strength with increasing addition of 3.0% brine.

Elaboration of a Self-Compacting mortar based on concrete demolition waste incorporating blast furnace slag

The high consumption of natural sand in the manufacture of mortar and concrete has inevitably led to serious ecological impacts. On the other hand, the steel industry is always accompanied by the production of unused by-products such as granulated blast furnace slag. This research aims to use a fine fraction of construction and demolition (C&D) waste as a substitute for natural sand and, ground granulated blast furnace slag (GGBFS) as a substitute for cement for the manufacture of self-compacting mortars. 15 mortars are formulated where 0, 25, 50, 75 and 100% natural sand (NS) are replaced by recycled concrete sand (RCS) and 0, 20 and 40% ordinary cement are replaced by GGBFS. The obtained results show that it is possible to manufacture self-compacting mortars with RCS, with an optimum of 50%. The use of this type of sand affects negatively the porosity and capillarity water absorption of mortars; this can be compensated by the use of GGBFS as a cement substitute. A 20% slag substitution rate can also improve the long-term compressive strength.

Enhancing the properties of UPOFA-based geopolymer mortar via the incorporation of eggshell ash and silica fume

The aim of this study is to utilize the largest amount of ultrafine palm oil fuel ash (UPOFA) with the incorporation of additives namely eggshell ash (ESA) and silica fume (SF) in the manufacture of geopolymer mortar through the use of a statistical design program (Taguchi). The efficiency of UPOFA source material in the production of geopolymer products has been investigated via four factors, namely the NaOH concentration (moles), Na-silicate: NaOH ratio, eggshell ash (ESA) content, and silica fume (SF) content, where each factor contains three different levels. Each of these factors was examined on three levels in order to obtain an optimal mixture. Nine (9) geopolymer mortar mixtures were prepared according to the proposed [L09 (3 × 4)] matrix by the Taguchi method. The performance of the samples was evaluated by compressive strength, ultrasonic-pulse velocity (UPV), porosity (P%), water absorption (Abs%) and density. The results showed that the optimum mixture consisting of 77 wt% UPOFA, 11.5 wt% of ESA and 11.5 wt% SF, achieved a very high compressive strength of 125.4 MPa after 28 days of curing. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analyses of the optimized UPOFA-based geopolymer mortar mixture indicated that the properties of the mixture were greatly improved with calcium silicate hydrate (C–S–H) gel as the main binding phases within the synthesized UPOFA-based geopolymer mortar. Therefore, through the production of this geopolymer mortar, a large amount of UPOFA in combination with ESA and SF could be one of the solutions for the environmental and landfill disposal problems in Malaysia, besides promoting greener Portland cement free binder with potentially superior properties and performance.

Use of Municipal Solid Waste Incineration Fly Ash in Geopolymer Masonry Mortar Manufacturing

The feasibility of partially replacing pulverized fly ash (PFA) with municipal solid waste incineration fly ash (MSWIFA) to produce ambient-cured geopolymers was investigated. The influence of mixture design parameters on the compressive strength of geopolymer paste was studied. The investigated parameters included MSWIFA dosage, the ratio of sodium silicate to sodium hydroxide (SS/SH), the ratio of liquid to solid (L/S) alkaline activator, and the ratio of SH molar. A water immersion method was selected as a pretreatment process for MSWIFA, leading to effectively maintaining the volume stability of the MSWIFA/PFA geopolymer. The mixture of 30% treated MSWIFA and 70% PFA with 12 M SS, 0.5 L/S ratio, and 3.0 SS/SH ratio produced the highest three-day compressive strength (4.9 MPa). Based on the optimal paste mixture, category four masonry mortars (according to JGJT98-2011) were prepared to replace various ratios of natural sand with fine recycling glasses. Up to a 30% replacement ratio, the properties of the mortars complied with the limits established by JGJT98-2011. The twenty-eight-day leaching rate of mortars containing 30% MSWIFA was lower than the limits proposed by GB5085.3-2007. Microstructural analysis indicated that the main reaction product was a combination of calcium silicate hydrate gel and aluminosilicate gel.

Point load test method for prediction strength of sustainable mortar made from blended cement and fly ash

Fly ash (FA) is a by-product of power plants where a number of serious efforts in the field of sustainable building materials have spawned a recycling method in the form of cementitious material containing FA as raw material, including blended cement. The contribution of blended cement to producing sustainable mortar is presented in this study. The FA at a percentage of 10% to 30% by weight of cement is used instead of blended cement in the manufacture of mortar. The results of the point load strength index (PLSI) at the age of 7 days the percentages of FA-0, FA-10, FA-20, and FA-30 were 0.58, 0.46, 0.41, 0.41 N/mm2 and at the age of 28 days were 0.88, 0.85, 0.79, and 0.78 N/mm2 respectively, indicating that the mortar produced with blended cement and FA is carried the point loads well because it has stiffness and adequate robustness. The contrast test with available methods verifies that PLSI offers an alternative to compressive test and it has high accuracy. The point load test method can be used to predict the strength of mortar produced of blended cement and FA.

Recycling of bamboo leaves and use as pozzolanic material to mitigate degradation of cementitious composites

The search for agro-industrial residues as supplementary cementitious materials has intensified as a result of the desire for more sustainable products and a reduction in the environmental effect of non-renewable natural resource exploitation. Pozzolanic materials offer a series of advantages, among them, the reduction of porosity and improvement to the attack of external agents, such as the acids present in the rains of industrial regions that accelerate the degradation of concrete structures. Several agro-industrial residues have been studied, including bamboo leaf ash (BLA), which has shown positive results in terms of reactivity and compressive strength. The objective of this work was to evaluate the ability of BLA to act as a mitigating agent of acid attack when incorporated to mortars. The BLA was produced by self-combustion and the physical chemical analysis showed the formation of amorphous material, with a predominance of silicon oxide. BLA was used to partially replace Portland cement ARI V, at 20 and 30%, in the manufacture of mortars. Prismatic specimens of the reference and experimental mortars were cured in an acid environment (5% sulfuric acid). The mechanical tests of resistance to bending and compression, at 7 and 28 days of curing, show that there was no change in these properties, as a result of the replacement (p>0.05). However, when evaluating the loss of mass of the specimens, it was observed that the reference specimens suffered greater loss in relation to those constituted by BLA, in both percentages (p<0.05). In this way, the results of this work demonstrate the feasibility of using BLA as a substitute for Portland cement, with environmental gains, due to use of waste, economy of non-renewable raw materials and energy, in addition to the advantage of mitigating the effects of acid attack on mortars. • Ash from bamboo leaves can be recycled as pozzolanic material • Sustainable alternative mortars with BLA are resistant to aggressive environments • Mortars with OPC replaced by 30% of BLA reached same compressive strength of reference.

Physical and Mechanical Properties of Dune Sand Mortar Reinforced with Recycled Pet Fiber: An Experimental Study

Abstract Polyethylene terephthalate is a synthetic material known as PET. PET strapping bands is a material commonly used in all industries for packaging and bundling. The excessive use of this material has led to the pollution of the urban environment, which necessitated the search for effective solutions to dispose of this waste. The treatment and reuse of these materials is among the best solutions that contribute to reducing environmental pollution on the one hand and enabling the obtaining of economical products on the other hand. The main purpose of this experimental study is to valorize dune sand mortar and PET waste in the manufacture of cement mortar. It also aims to investigate the impact of the inclusion of recycled PET fibers on the physical and mechanical properties of the reinforced mortar. The study was carried out in several phases; after a physical and chemical characterization of the materials used, a method for the composition of mixtures was proposed, which is based on the progressive substitution of dune sand by recycled PET fibers. The quantity of cement added to each mixture is fixed at 450 g, and that of dune sand and fibers is taken as equal to 1350 g. In order to properly examine the influence of the incorporation of fibers on the properties of the reinforced mortar, the substitution rate of dune sand by the fibers varied from 0% to 2.5% with a step of 0.5%. For each mixture, many characteristics of the mortar were tested, such as consistency, bulk density, compressive strength, and flexural strength. The results obtained show that the incorporation of PET fibers has a significant effect on the fresh and hardened properties of the treated mortar.

Physical-mechanical Evaluation of Polyethylene Terephthalate Fiber Dune Sand Mortar Exposed to Elevated Temperature

Abstract The mechanical properties of mortar containing Polyethylene Terephthalate (PET) as Strapping Band Fibers (SBF) replacing natural sand have been studied by many researchers. These studies indicate that when SBF is used as a substitute for sand in mortar, the characteristics in both the fresh and hardened states are altered. This experiment’s purpose is to valorize local materials, which are abundant in the region of Djelfa (Algeria), in cement mortar manufacturing and to discuss the influence of these materials on the mechanical and physical characteristics of the resulting mortar at the room, and at the high temperature. This study presents the results of an experimental investigation into the effects of high temperatures on the properties of dune sand mortar made with strapping band fibers. The method for formulating the mortar mixes was based on the progressive replacement of dune sand by PET fibers, with weight contents of 0%, 0.5%, 1%, 1.5%, 2%, and 2.5%. Several tests have been carried out to study the evolution of the different characteristics of mortar mixtures. The workability, bulk density, compressive and tensile strengths, and all samples were subjected to temperatures of ambient, 100 °C, 200 °C, and 400 °C. The results demonstrate that the inclusion of the recycled fibers and the preservation mode had remarkable effects on the characteristics of the mortar obtained.

Development of a Portland Cement-Based Material with Agave salmiana Leaves Bioaggregate.

Depending on the morphology of the natural fibers, they can be used as reinforcement to improve flexural strength in cement-based composites or as aggregates to improve thermal conductivity properties. In this last aspect, hemp, coconut, flax, sunflower, and corn fibers have been used extensively, and further study is expected into different bioaggregates that allow diversifying of the raw materials. The objective of the research was to develop plant-based concretes with a matrix based on Portland cement and an aggregate of Agave salmiana (AS) leaves, obtained from the residues of the tequila industry that have no current purpose, as a total replacement for the calcareous aggregates commonly used in the manufacturing of mortars and whose extraction is associated with high levels of pollution, to improve their thermal properties and reduce the energy demand for air conditioning in homes. Characterization tests were carried out on the raw materials and the vegetal aggregate was processed to improve its compatibility with the cement paste through four different treatments: (a) freezing (T/C), (b) hornification (T/H), (c) sodium hydroxide (T/NaOH), and (d) solid paraffin (T/P). The effect of the treatments on the physical properties of the resulting composite was evaluated by studying the vegetal concrete under thermal conductivity, bulk density, and compressive strength tests with a volumetric ratio between the vegetal aggregate and the cement paste of 0.36 and a water/cement ratio of 0.35. The hornification treatment showed a 15.2% decrease in the water absorption capacity of the aggregate, resulting in a composite with a thermal conductivity of 0.49 W/mK and a compressive strength of 8.66 MPa, which allows its utilization as a construction material to produce prefabricated blocks.

Partial Replacement of Municipal Incinerated Bottom Ash and PET Pellets as Fine Aggregate in Cement Mortars.

The objective of this study was to examine the optimal mixing ratio of municipal incinerated bottom ash (MIBA) and PET pellets used as a partial replacement of fine aggregates in the manufacture of cement mortars. As a partial replacement for sand, 15 mortar specimens were prepared by mixing 0%, 10%, 20%, 30%, and 40% municipal incinerated bottom ash (MIBA) (A) and 0%, 10%, and 20% PET pellets (P) in 5 cm × 5 cm × 5 cm cube molds. The cement/aggregate ratio was 1:3, and the water/cement ratio was 0.5 for all specimens. The results showed that the compressive strength of cement mortars decreased when increasing the amount of MIBA and PET pellets. The mortar specimens with 10% PET pellets achieved the highest compressive strength (49.53 MPa), whereas the mortar specimens with 40% MIBA and 20% PET pellets achieved the lowest compressive strength (24.44 MPa). Based on this finding, replacing 10% and 20% sand in cement mortar with only MIBA or only PET pellets could result in compressive strengths ranging from 46.00 MPa to 49.53 MPa.

Properties of mortar made with bottom ash and silica fume as sustainable construction materials

PurposeThis study aims to investigate the properties of mortar made from a bottom ash substitute as a sustainable construction material. It is believed that the use of cement in concrete construction contributes to the release of carbon dioxide into the atmosphere, which has been a consistent increase in recent years. The utilization of bottom ash waste is expected to reduce pollution associated with cement production.Design/methodology/approachBottom ash is used as replacement materials for cement and fine aggregate in the manufacture of mortar. Bottom ash substituted for cement of 10%, 20% and 30% of the total weight of the binder, whereas bottom ash substituted for the fine aggregate of 30%, 40% and 50% of the total weight of the sand. Binder properties were determined using scanning electron microscopy and energy dispersive X-ray. Meanwhile, the fresh properties (slump flow) and hardened properties were determined (compressive strength and mass density). In the hardened properties test, two types of curing were used: water and sealed curing.FindingsThe compressive strength of mortar decreased as the amount of bottom ash as cement replacement. However, the compressive strength increased when bottom ash was used as aggregate replacement. Additionally, bottom ash was sufficient as a substitute for fine aggregate than as a substitute for cement.Originality/valueThis research presents test results that are more straightforward to apply in the construction site.

Strength, electrical resistivity and sulfate attack resistance of blended mortars produced with agriculture waste ashes

The performance of blended mortar mixtures produced with partial replacement of cement with agriculture waste ashes of rice husk, sugarcane bagasse, corncob, and waste wood were evaluated in this investigation. Cement was replaced at 5, 10, and 15 wt% with each of agriculture waste ashes for manufacturing of blended mortars. Fresh mixture properties, compressive strength, electrical resistivity, and sulfate resistance of the mixtures were evaluated at 7, 28, 56, and 90 days of curing ages and compared with that of control mixture.Test results showed a significant improvement in the later age compressive strength, electrical resistivity and sulfate resistance of blended mortar mixtures. Considerable increase in the initial and final setting times of the blended mortar mixtures was noted. Increasing demand for the superplasticizer dosage to achieve the target flow level was recorded with increase in percent replacement of cement with the agriculture waste ashes. Blended mortar mixtures produced with rice husk ash as partial replacement of cement showed superior performance among the four types of mixtures. A replacement level of 10 wt% of cement with the agriculture waste ashes was observed to be the optimum to achieve enhanced strength and durability of the blended mortar mixtures.

Influence of Sand Casting Waste as Substitutor of Quartz Sand in Mortar

Sand casting waste has the potential to replace quartz sand in mortar manufacture because it contains high silica. This study uses sand casting waste from the steel industry in Gresik, Indonesia to observe how it affects the quality of the mortar. Initial characterization were carried out to determine the properties of the material, including; magnetic test which results are not attracted by magnets, moisture content test with a value of 0.328%, XRD test to determine the crystallinity content which results contain 99.52% Silica Quartz, and XRF test to determine the content of the compound in which results are 81.25% Silica dominant. Then observations were made by making mortar with the replacement of quartz sand by sand casting with variations of 0% wt, 25% wt, 50% wt, and 100% wt and then tested its compressive strength at 3 days, 7 days, and 28 days. Based on the research that has been done, the optimum result using sand casting is at 25% wt with a compressive strength of 251.15 kgf/cm2 at 28 days of age which is higher than the standard.

Recycled sand from sandstone waste: A new source of high-quality fine aggregate

The construction industry is facing a shortage issue of river sand, therefore broadening new sources of fine aggregate is imminent. This paper demonstrates the feasibility of a recycled sand from sandstone waste in mortar manufacturing by comprehensive assessment of workability, mechanical properties, water absorption, alkali silica reaction (ASR). The recycled sandstone sand (S-sand) has a smoother microscopic morphology and better particle size distribution than river sand (R-sand). Fine particles smaller than 150 µm in R-sand usually contain a large amount of impurities (such as clay) and are considered harmful. However, the S-sand containing ∼15.7% µm quartz grains <150 µm significantly improves the mortar performance in terms of compressive strength and ASR property. At the same water to binder ratio, the mortar using the S-sand shows worse workability than that using R-sand but a slight increase of water to binder ratio or adding water reducer improves not only the workability but also mechanical properties. For the ASR test, the S-sand shows potential uncertain risk as per ASTM C 1260. Using calcined clay or fly ash to replace 25% cement can effectively inhibit expansion risk. The compressive strength is reduced due to ASR, however, as the ASR progresses, it is somehow restored. This study also finds the good linear relationship between length change of mortar bar and mass change, which can be used to predict the sand ASR property. The results showed that S-sand produced by waste sandstone by-products can be used as high-quality fine aggregate.

Substitution of limestone filler by waste brick powder in self-compacting mortars: Properties and durability

The feasibility of using waste brick powder (WBP) in the manufacture of self-compacting mortar has been investigated in this study. The limestone filler was partially or totally (0%, 50% and 100%) substituted with WBP. The rheological properties, compressive and flexural strengths, drying shrinkage and durability properties (including carbonation resistance, chloride ion diffusion and sulphate resistance) of self-compacting mortars were evaluated. The WBP-mortars presented a higher yield stress and plastic viscosity than that of WBP-free mortar: the additional water has to be added in order to achieve the equivalent workability. The compressive strength of WBP-mortars slightly decreased after 7 days (the compressive strength of series mortars M − BP decreased 5.6% and 9.3% for 50% and 100% WBP based mortars comparing with the reference mortar, respectively; while the compressive strength of series with similar workability mortar M-BP100WA which was based on 100% WBP decreased 16.7% and it could achieve 26.8 MPa), but the decreasing trend seemed to be compensated by the pozzolanic activity of WBP and remained equivalent after 28 days (the compressive strength of series mortar M-BP100WA decreased 5.3% and it could achieve 35.6 MPa). The substitution of limestone filler by WBP didn't seem to impair the durability behavior of mortars (except for the resistance to carbonation). Therefore, it is possible to manufacture self-compacting mortar by partially or totally substituting limestone filler by WBP.

Bacillus Subtilis as Self-Healing Agent in Cement Mortar: The Effect of Curing Time and Amount of Calcium Lactate on Strength

Crack growth is a major cause of failure in structures that are made using cement and concrete. Healing of these cracks can increase the life span of structures. In the present study micro-organism based self-healing of structures is studied. A commonly occurring micro-organism bacterium called Bacillus Subtilis, is used in the manufacturing of cement mortar blocks as a self-healing agent for cement mortar blocks, with the use of Calcium Lactate as feed for bacteria. In the first step, colonies of Bacillus Subtilis were grown and added with calcium lactate to produce a solution. The solution was then kept for one week to observe the metabolic product of Bacillus Subtilis. It was found that the bacterial product was composed of CaCO3 and thus the bacteria is suitable to be used as self-healing agent. Self-healing cement mortar blocks were made by adding Bacteria and Calcium Lactate with usual ingredients of cement mortar, i.e. cement, sand and water. It was found that the bacteria were also effective in converting Calcium Lactate to Calcium Carbonate, when mixed in cement mortar blocks. It was observed that the pores of cement mortar blocks were filled by Calcium Carbonate and that cracks get healed by the deposition of Calcium Carbonate in the cracks. Cement mortar blocks, with and without healing agent, were made to compare the effect of curing time. The samples were tested after seven, fourteen and twenty-eight days to compare the effect of healing agent. All the samples with the healing agent showed a higher compressive strength in comparison with the samples that were made without healing agent. Different percentages of Calcium Lactate, ranging from 1-7% were also used to find the best composition for future use. It was found that the compressive strength was increasing up to 5% while above 5% the increase was marginal thus it is proposed that Calcium Lactate should be used in between 5-7 % to reduce the cost of self-healing cement in construction industry.

Effects of a Natural Mordenite as Pozzolan Material in the Evolution of Mortar Settings.

This paper shows the results of a study focused on the evolution and properties of mortars made with a mixture of portland cement (PC) and natural mordenite (Mor). To begin, samples of mordenite, cement and sand were studied with X-ray diffraction (XRD), X-ray fluorescence (XRF) and granulometric analysis (GA). Next, mortars with a ratio of 75% PC and 25% mordenite were prepared to determine their initial and final setting times, consistency and density. Continuing, the density, weight and compressive strength of the specimens were determined at 2, 7, 28, 90 and 365 days. Finally, the specimens were studied using SEM, XRD and XRF. The results of the study of the mordenite sample showed a complex constitution where the major mineral component is mordenite, and to a lesser degree smectite (montmorillonite), halloysite, illite, mica, quartz, plagioclase and feldspar, in addition to altered volcanic glass. Tests with fresh cement/mordenite mortar (CMM) showed an initial setting time of 320 min and a final setting time of 420 min, much longer than the 212–310 min of portland cement mortar (PCM). It was established that the consistency of the cement/mordenite mortar (CMM) was greater than that of the PCM. The results of the density study showed that the CMM has a lower density than the PCM. On the other hand, the density of cement/mordenite specimens (CMS) was lower than that of portland cement specimens (PCS). The CMS compressive strength studies showed a significant increase from 18.2 MPa, at 2 days, to 72 MPa, at 365 days, with better strength than PCS at 28 and 365 days, respectively. XRD, XRF and SEM studies conducted on CMS showed a good development of primary and secondary tobermorite, the latter formed at the expense of portlandite; also, ettringite developed normally. This work proves that the partial replacement of PC by mordenite does not have a negative effect on the increase in the mechanical strength of CMS. It indicates that the presence of mordenite inhibits the spontaneous hydration of C3A and controls the anomalous formation of ettringite (Ett). All this, together with the mechanical strength reported, indicates that mordenite has a deep and positive influence on the evolution of the mortar setting and is an efficient pozzolan, meaning it can be used in the manufacture of mortars and highly resistant pozzolanic cement, with low hydration heat, low density, stability in extremely aggressive places and a low impact on the environment.

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.