Lime mud from a pulp mill was used as an additive in brick clay from the southern part of Thailand. It was mixed with the clay from Cha-Aud district, Nakorn Sithammarat province. The chemical composition of lime mud and the clay was characterised by X-ray fluorescence (XRF), and the mineralogical composition was measured by X-ray diffraction (XRD). The particle size distribution was also measured. The main composition of lime mud is CaO, and Cha-Aud clay consists of SiO2 and Al2O3 as major oxides. The lime mud contains calcite as a major phase when Cha-Aud clay is constituted by quartz, kaolinite, illite and goethite. Particle size distribution of lime mud is in the range of 1-50 μm. After the lime mud was neutralized using hydrochloric acid, it was mixed with Cha-Aud clay at 10 wt%. Samples with and without lime mud were sintered at 700, 800, 900 and 1000°C for 1 hour. The results showed that lime mud can be used as an additive in brick clay. Both types of samples were similar in terms of physical properties when their linear firing shrinkage, water absorption and flexural strength were in the same range.

In this project, limestone dust from a limestone crushing plant was mixed with several pottery clays from the Northeasetern part of Thailand, i.e., Ban Ponsai, Ban Tha Hai, Ban Nanuan and Ban Nam Kamnoi. The limestone dust was sieved and then mixed with 4 sources of clays at 50 wt%. Samples with and without limestone dust were sintered at 700°C for 1 h. Compared to the samples without limestone dust, the samples with limestone dust showed higher flexural strength and slightly higher water absorption, but lower linear firing shrinkage. Furthermore pottery was produced using the mixture of pottery clay and limestone dust.