Alkali activation of fly ash (FA) is a chemical process which allows the transformation of the amorphous structure which makes up most of its particles, in compact cementitious skeletons geopolymers are called solid materials usually consist of a alkali hydroxide and solid precursor high content in silicon (Si) and aluminium. This paper presents the effect of temperature and the curing time in the alkali activation in FA pastes with 8M NaOH, geopolymers curing was carried out at room temperature, 60 °C and 80 °C at aged 7 14 and 21 days. Compression tests were conducted to obtain the strength of the geopolymer and analysis by X-ray diffraction to determine the new phases present resulting in higher compression resistance with higher temperature and curing time, a change was detected in the diffractogram because new phases present in the alkaline activation product.
In the search for alternative solutions for the recycling of ceramic waste from both of the industry as the demolition and as contribution to the conservation of the environment, treatment of this waste is being implemented so that they can be incorporated back into the construction industry, both in mortars and concretes. In this work has made an assessment on the properties of mortars containing ceramic waste (as aggregate), focusing on those presented in its fresh State (consistency, density and air content), since these can influence the quality of the execution of the work and even contribute in the properties of hardened state; therefore, mixtures with different percentages of arid ceramic instead of the usual aggregate, as well as with different relationships c/a were performed. The results show that the effect of ceramic aggregate content has greater influence than the relation c/a in the fresh properties of recycled ceramic mortars.
At present generation of domestic and industrial waste is a serious problem that must be controlled, so it is necessary to conduct further research of materials that minimize this problem by incorporating domestic and industrial waste in them; these materials must provide suitable properties, and perform the same function as the traditional material complies with virgin materials. This research focused on explaining the mechanical effects caused by overdose of unsaturated polyester resin made from post-consumer bottles made with polyethylene terephthalate (PET) (R-PET), cement-R- PET pastas and polymer modified mortars (PMM) with total or partial substitution of the recycled fine aggregate (AR) and additions of R-PET. The TGA and XRD results show that there is less development of the hydration products to a higher content of R-PET, causing reduction in the compressive strength of the PMM.
Mechanical and maturation of geopolymers mortars based on fly ash –FA? (FAM), properties are studied. The values of FAM in compressive strength were lower than conventional Portland cement mortars (PCM). For geopolymers were achieved in some cases compressive strengths up to 24.42 MPa, but in another study variables an abnormal behaviour was identified with loss of compressive strengths and elastic modulus (reaching only 14.51 MPa and 1.24 GPa). This behaviour can be attributed to a possible reaction between the aggregate and the alkaline medium, which appears to increase with +age of curing. Involvement implies that the reaction impedes or disrupts the geopolymerization process of FA, causing less compressive strength.
Wear is a complex phenomenon and the most important reason for the damage and consequent failure of machine parts. The dry sliding wear performance of particulate reinforced aluminum metal matrix composites (Al-MMCs) are being investigated by numerous researchers during the last three decades. A lot of experiments have to be conducted in order to study the wear behavior. Artificial Neural Networks help in reducing the cost of experimentation when implemented with care and enough data. In this work, wear behavior of Al7075 aluminium matrix composites reinforced with particulates has been investigated. The Al7075-SiC metal matrix composites were fabricated through liquid metallurgy process containing 2-6 wt% SiC. The dry sliding wear tests were conducted using computerized pin on disc wear testing machine. The wear properties of the composites containing SiC were better than that of the matrix material and further, the composite containing 6 wt% SiC content exhibited superior wear resistance. An ANN model was developed to predict the tribological properties of the Al7075-SiC composites. The predicted values of tribological
Acoustic signals emitted from plastically deformed copper specimens were analyzed with respect to the grain size and strain rate employing a kinematic model. The data are interpreted in terms of an acoustic emission parameter related to the behavior of copper while undergoing plastic deformation.
