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This research aimed to study the mixing ratios of fly ash and rice husk ash on the physical properties and thermal conductivity of soil geopolymer block. Fly ash to rice husk ash ratios for this experiment were 100:0, 80:20, 70:30, 50:50, 30:70, 20:80 and 0:100 %wt, respectively. The properties analysis of soil geopolymer block such as the compressive strength, water absorption, apparent porosity, bulk density and thermal conductivity were tested. The results indicated that soil geopolymer block of 80:20 %wt at 28 days of curing gave the maximum compressive strength of 131.43 kg/cm2. The minimum water absorption of 7.70 %, minimum bulk density of 2, 056.34 kg/cm3, minimum apparent porosity of 15.64 %, minimum thermal conductivity of 1.8674 W/m.K, were obtained. The compressive strength of soil geopolymer block increased up to 87 % and the thermal conductivity has decreased to 35 % compared to commercial cement block. The compressive strength, the water absorption and the bulk density of 80:20 %wt mixtures was in accordance with the standard product community at 602/2547 that can be used in construction applications.

This research was presented the physical and thermal conductivity properties of cement pastes containing nanosilica by mixing three nanosilica particle sizes of 12, 50 and 150 nm, using nanosilica of 1-5 wt%. The water-cementitious ratio (W/C) was 0.5 for all samples. Thermal property coefficients were tested using a direct measuring instrument with surface probe (ISOMET2114). The influence of nanosilica on the physical properties were compressive strength, bulk density, XRD and SEM respectively. The results indicated that the use of nanosilica as an admixture can reduce the thermal conductivity and lowered the bulk density of specimen. The cement paste with nanosilica particle size of 50 nm with 4 wt% nanosilica at the age of 28 days showed the optimized properties. The thermal conductivity was lowest at 0.913 W/m-K, the compressive strength was highest at 51.62 MPa and the bulk density was 1,806 kg/m3respectively. The compressive strength increases more than 50% higher than that of pure paste. The cement pastes with nanosilica particle sizes of 50 and 150 nm, have lower unit weight and thermal conductivity than typical control cement paste about 9% and 15% respectively. The nanosilica mixed cement paste is very interesting for energy saving when used as wall insulating material.

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