In the current study, improvement of HAp/Calcined kaolin (CK) strength as a function of its curing regime was studied. The influence of curing temperature and time on the compressive strength of hydroxyapatite combined with calcined kaolin (HAp/CK) samples was investigated using statistical analysis. Curing temperatures were ranged 40, 60, 80°C and curing times were 2, 7, 14, 21, 28 days, respectively. Prolonged curing time and increased curing temperature improved the compressive strength of the samples. The curing time and temperature significantly affected the compressive strength of HAp/CK samples, while there was no interaction between curing time and curing temperature. The highest compressive strength, 37.8 MPa, was realized by curing the sample at 80°C for 28 days. The optimal process was curing HAp/CK at 60°C for 14 days to achieve a high compressive strength.

This study aims at investigating the effect of the main biomass characteristics (moisture content and particle size) on durability of Cassava stalk residues pellets. This durability is necessary to consider design of the material handling, processing equipment, storage and transportation of biomass pellets. The raw biomass materials were ground and screened into four range sizes and pelletization was done at three different percentage levels of moisture conditions defined as percentage of added water by mass of raw material. Pellets in each condition were analysed for durability. The result showed that the highest durability occurred in particle size 1.7 mm but less than 3.35 mm and 10% moisture content by mass of raw biomass material. The mean durability in the best conditions was 99.02%. This information is important for the design and efficient preparation of biomass material for pelletization to achieve the high quality pellets with high durability for handling, transportation and storage.

Cassava (Manihot Esculenta, Crantz) is the third most important source of calories and the sixth most important crop cultivated in tropical and subtropical areas around the globe. The growth in cassava production is likely to accelerate over the current decade (FAO 2008;Burns 2010). In Thailand, cassava has been widely cultivated with a total area of approximately 8,975,865 Rai or 1,436,138.40 ha across the country, which results in annual production of around 30,022,052 t (OAE 2014). In traditional cassava harvesting, the stalks are cut and collected from the field, then the roots are pulled out from the soil either by hand or machine. About 30% of stalks are kept for cultivating in the next season, while the remaining 70% are abandoned in the field as agricultural residues (FAO 2008). These residues can be used as raw materials for biomass applications due to high volume of residues and heating value of 15.40 MJ/kg (DEDE 2009). This could help Thailand to reduce energy imports, carbon emission, improve energy sustainability, and also increase farmer income (Kronbergs, Smits 2009; Khongthong, Sudajan 2014). Despite the aforementioned benefits, biomass material produced from cassava usually suffers from low density and inconsistent size. This affects transportation costs considerably. To solve the problem, the cassava residues must be chopped by chopping machine before becoming biomass energy. As a result, a proper chopping machine must be developed. Also, physi- In an attempt to investigate the potential of using cassava stalk as a biomass material and determine the design requirements for developing a cutting machine, this study aims to investigate physical and mechanical properties of cassavas stalk, under the influence of moisture content and region of cut using statistical techniques. Moisture contents were ranged into three different levels; 54.19, 43.05 and 24.93% wet basis (w.b.) while cutting regions were classified as top (tip of cassava stalk), middle and bottom. Mechanical properties were represented by shearing stress. Physical properties, on the other hand, were represented by length, diameter, and mass. By decreasing moisture levels, all parameter values were reduced, except shearing stress. Moreover, it was found that shearing stress increased when lowering the cutting line. Maximum and minimum shearing stress occurred at bottom and top regions of the stalk, respectively. Most importantly, moisture content and region of cut both had a significant influence (P < 0.05) on shearing stress, although the latter had much larger impact.

In the current study, improvement of HAp/Calcined kaolin (CK) strength as a function of its curing regime was studied. The influence of curing temperature and time on the compressive strength of hydroxyapatite combined with calcined kaolin (HAp/CK) samples was investigated using statistical analysis. Curing temperatures were ranged 40, 60, 80°C and curing times were 2, 7, 14, 21, 28 days, respectively. Prolonged curing time and increased curing temperature improved the compressive strength of the samples. The curing time and temperature significantly affected the compressive strength of HAp/CK samples, while there was no interaction between curing time and curing temperature. The highest compressive strength, 37.8 MPa, was realized by curing the sample at 80°C for 28 days. The optimal process was curing HAp/CK at 60°C for 14 days to achieve a high compressive strength.