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This paper presents a parametric experimental study which investigates the potential use of buckwheat husk wastes (as an aggregate in concrete) and opoka combination for producing a lightweight composite. The study was carried out to investigate the influence of the buckwheat husk extract on the setting and hardening of pastes in which cement was partially replaced by 0, 33, or 50 % of natural pozzolana. The kinetics of hydration up to 48 h was studied using isothermal conduction calorimetry. Some of the physical and mechanical properties of buckwheat husk concrete with various levels of cement replacement of opoka without and with sand (part of buckwheat husk was replaced in the same volume of sand) were investigated. Experimental data on the compressive strength of concrete utilizing buckwheat husk with and without sand and cement at varying proportions are presented. The results suggest that buckwheat husk may be used as an aggregate, particularly in lightweight concrete, panel and blocks for walls at a relatively cheaper price.

This study investigated the possibility of using artificial materials obtained during combustion of mica clay as an additive for Portland cement. The mica clay granules were burned at 700–1100°C for 1 h. It was considered that the pozzolanic activity of the investigated mica clay would depend on the combustion temperature. The highest pozzolanic activity (134 mg calcium oxide (CaO)/g) was observed in the samples calcined at a temperature of 900°C. In the samples, 5, 10, 15 and 25% (by weight) of the Portland cement was replaced with calcined additive at the temperature of 900°C. The samples were then hardened for 28 d under normal conditions. Owing to relatively low pozzolanic activity, the pozzolanic reaction in the samples with the additive up to 28 d of hydration was not noticeable. However, calcined mica clay additive acted as a microfiller and significantly increased the rate of hydration of Portland cement clinker minerals. The calcined mica clay additive had a positive effect on the compressive strength of samples cured for 28 d under normal conditions because up to 15 wt% of ordinary Portland cement can be replaced with the additive being investigated without impairing the strength class of the cement.

During utilization of animal waste meat and bone meal (MBM) is received, realization and use of which has been stopped due to risk for the transmission of the bovine spongiform encephalopathy infection. The MBM must be safely stored or treated. Most often meat and bone meal undergoes thermal treatment. During combustion large quantities of residues (ashes) are received, the recycled use of which has been given a lot of attention lately. In this work it was investigated the impact of the additive of the bottom ash (BA) formed during combustion of the MBM on the properties of forming mass and ceramic body of hydromica clay, and also it was evaluated a possibility to use the MBM BA in manufacturing of building ceramics. After replacing the sand in porous ceramics by this additive the plasticity of the forming mass, drying and firing shrinkage as well as density of ceramic body changed insignificantly whereas the compressive strength increased by 8 % - 22 %. So the MBM BA can be utilized in production of porous ceramics.

http://dx.doi.org/10.5755/j01.ms.17.1.256

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