Blended cements are very uncommon in Pakistan, and most of the supplementary cementitious materials (SCM) are used during the concrete production. With the increasing demand and scarcity of high-quality SCMs, cement industries are exploring new variants of blended cement for meeting the needs of the building and construction industry. Ongoing research on novel LC3 drew the attention of Fauji Cement Company Limited—a leading cement manufacturer in the country. We have explored many areas in the vicinity of the cement plant in search of potential clay reserves and found a vast range of naturally occurring clay containing 40 to 85 wt.% kaolinite mineral, suggesting its qualification for producing LC3 cement blend. During the exploration of kaolinite clay, it was observed that the region is enriched in white China clay and also has massive reserves of reddish clay which contains high kaolinite as well as iron contents. This typical reddish clay is not in the use of any industry, and its potential reserves are best suited to be used for manufacturing LC3. Different grades of fine calcined clay samples were mixed with ordinary Portland cement (CEM I 42,5 R) to prepare LC3-50 and LC3-65. Composition and performance of the resulting building materials were tested using XRF, PSD, standard consistency, setting times, compressive strengths, etc., as well as in an actual civil construction project for the first time in Pakistan by a cement manufacturer. Test results showed excellent compressive strength for up to 50% clinker replacement, indicating that clays of this region are suitable to be used for LC3 cement production.