A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science, School of Civil Engineering

Thesis (M.Sc.) - Asian Institute of Technology

Dimensioned stone properties of hornblendite and diorite from Nakhon Ratchasima, northeastern Thailand , were investigated . Both rocks have black color since both are composed mainly of hornblende crystals especially in hornblendite where the large euhedral hornblende crystals comprise almost entirely of the rock and give the rock a very attractive appearance. In diorite, the presence of colorless plagioclase and brassy colored pyrite reduced its black color somewhat. Both hornblendite and diorite are very dense rocks with very low porosity and void ratio as well as water content. The dry density of hor~blendite is 3.18 g/cm3 and the dry density of diorite is 3.28 g/cm · The hornblendite is medium to high-strengthed rock and the diorite is high to very high-strengthed rock. The uniaxial compressive strengths of hornblendite range from74.23 MPa to 149.33 MPa and the uniaxial compressive strengths of diorite range from 196.49 MPa to 331.85 MPa. The mechanical properties of the rocks are not uniform mainly because of the variation of their grain size. The durability tests results of hornblendite showed that it is durable except that its strength will decrease somewhat when it is saturated with water, its softness index is 0.69. The durability tests results of diorite showed that it is very durable but sensitive to acid and so it is not suitable to heavy erosive environment. The softness index of diorite is 0.94. The average raximum thermal expinsion of hornblendite and diorite are 5.6 x 10- ;0c and 6.59 x 10- ; 0c respectively showing that they are heat resistant and no combustible minerals exist in both of the rocks except that very few quartz grains are found in di or i te. Both rocks can be used as good dimensioned stone under conditions of use based on their properties.