Glass waste used in mortars or concretes behaves similar to cement, with resulting environmental benefits. In this light, the behavior of glass powder of various particle sizes has been analyzed as a cement replacement in mortars, in an attempt to minimize the loss of strength and durability, and maximize the amount of materials replaced. The dry density, water accessible porosity, water absorption by immersion, capillary absorption coefficient, ultrasonic pulse velocity and both compressive and flexural strengths were studied in the mortars. Furthermore, a statistical analysis of the obtained results and a greenhouse gases assessment were also performed. In view of the results obtained, glass powder of 38 microns allows up to 30% of the cement to be replaced, due to the filler effect combined with its pozzolanic activity. Moreover, it has been observed that glass powder size is one of the factors with the greatest influence among the properties of porosity, absorption and capillarity. On the other hand, in the mechanical properties, this factor does not contribute significantly more than the amount of glass powder. Finally, the greenhouse gasses analysis shows that the incorporation of glass powder reduces the CO2 emissions associated with mortar up to 29.47%.

It is well known that cement production has a high negative impact on the environment. This fact, in conjunction with the high demand for this product worldwide, has created concern over how to reduce its use. Various materials have been tested as partial or total replacements for cement, one of which is biomass ash. In this article we report the preparation of test samples of mortar using two types of biomass ash, the first of forest origin and the second agricultural; both were used to replace cement in proportions of 10%, 20% and 30%. The test samples were assayed for compression and flexion after 7, 14, 28 and 90 days. After 28 days the apparent density, open porosity, absorption, capillarity and ultrasound velocity were measured. All the results of the series were compared with a control mortar. In the compression and flexion assay, a higher resistance than the control mortar was obtained with 10% replacement of both types of ash after 90 days, however with 20% and 30% ash the results were inferior to traditional mortar. There was an increase in the absorption percentage and porosity as the percentage of cement replacement increased; this increase was smaller for ash from agricultural biomass than ash from forest biomass. The density diminished as the percentage of replacement material increased, but the change was smaller with ash from agricultural biomass; this may be attributed to a filler effect produced by its granulometric distribution.

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