Experimental Study On Compressive Strength Of Raw Soil Material Modified By Stones,Sand And Cement

As a kind of traditional architectural form,raw soil buildings still exist widely around the world and the vast rural areas of China rely on its advantages,such as convenient to draw on local resources,simple construction,insulation performance,green environmental protection,etc.However,its disadvantages of low strength,poor water resistance and poor stability restrict the development of raw soil building.Therefore,to preserve and inherit the traditional architectural culture,improving the mechanical properties of traditional raw soil materials fundamentally is the only approach.A lot of modified researches have done before,which ignored the phenomenon that raw materials containing stones in the construction of raw soil buildings,and causing some differences between the test result of soil as raw material and the actual force performance of the raw soil dwelling,starting from this point to study on the content of stone in soil and modify raw soil material has more practical significance.In this paper,the loess in Xi'an area was taken as raw material,and stones were used as the basic admixture to modify raw soil.Based on the orthogonal test model of single adding stones,the 90 cube specimens of modified raw soil material with 100 mm in side length were prepared in the test.Based on the simplex lattice formulation experiment model of combined adding sand and stones,combined adding cement and stones,the 120 cube specimens with 100 mm in side length were made.Through the axial compressive strength test,the failure process,the failure form and load-displacement curve of modified raw soil specimens were compared,the compressive strength and deformability were analyzed.The results of single adding stones showed that a certain particle size and content of stones should be allowed existing in the raw soil material when making adobe wall,and the particle size of stones should be controlled under the wall thickness of 1/3.In the same time,the deformability of soil can be improved significantly by the incorporation of stones.When the particle size of stones between 20~30mm,and the mixing amount under 5%,the compressive property and deformation capacity are optimal,which providing reference for modifying raw soil material by stones and selecting particle size of stones in combined adding test.The results of combined adding test showed that the compressive strength and deformability of soil can be improved by combined adding sand and stones,but should control the combined mass of sand and stones not exceed 32% of total quality.The effect of combined admixture of cement and stones on the compressive strength is the most obvious,can reach 1.16~3.55 times to soil,and combined addition is more effective than single addition.When the proportion of sand,stones,raw soil was 0.1,0.05,0.85,and the proportion of cement,stones,raw soil was 0.144,0.078 and 0.778,the combination property of modified soil is optimal.Finally,based on the study of the influence laws of compressive strength with different admixtures and different amount,the regression equations between compressive strength and influencing factors were obtained,which provided the basis for the compressive strength value of the modified raw soil material,and provided a reference for the practical application in engineering.