A study of bamboo as reinforcement for rice bins

Abstract

The purpose of this investigation is to study the suitability of bamboo as reinforcement for conical rice bins, and to compare the theoretical analysed structure of conical rice bins as composite and isotropic materials to the field test measurement of deflections and strains of a conical rice bin. The mechanical properties of bamboo and mortar were determined by tests, the result of which will be used in the design. Bamboo, one of the most common materials available in many parts of Thailand, may be proved to be a good substitute for steel because of its high tensile strength and is also the low-cost construction material. In the investigation a variety of bamboo scientifically called Thrsostachys Oliveri Gamble known locally as Pai Ruak in Thailand was used. The test results also showed that the average ultimated tensile strength, the average modulus of elasticity and the average bond stress between bamboo and mortar are 1937 kg/sq.cm, 2.64 x 10⁵ kg/sq.cm and 8.35 kg/sq.cm respectively. The mortar used for all the test samples had cement-sand ratio of 1 : 2 by weight with a water cement ratio of 0.45. The average ultimate compressive strength and the average modulus of elasticity of mortar were determined by cylindrical control specimens (15 cm. dia. X 30 cm.) as 408 kg/sq.cm and 3.0 x 10 kg/sq.cm respectively and from cube control specimens (5.0 cm x 5.0 cm x 5.0 cm) as 325 kg/sq.cm and 3.25 x 10⁵ kg/sq.cm respectively. A prototype rice bin was constructed at the site at Chulalongkorn University. Measurements were carried out, using dial gages for deflections and electrical resistance strain gauges for strains at various positions shown in Figs. (22), (23). Test results showed that the bin occurred higher deflactions than the deflactions calculated from theoretical analysis about 50 percent. The bin did not crack but sparse permeation in the bin occurred. This is because there is a loss of moisture content of mortar during construction, and because the mortar had not been mixed with sealing compound and also because the water pressure was 2.25 m. height which was too high. The compressive strength of mortar occurred lower than the compressive strength calculated from theoratical analysis about 19 percent but the tensile strength of bamboocement was equal to those calculated.