Two　processing　techniques,　i.e.,　grinding　and　calcination　taken　on　fine　powders　from　recycling　of　concrete　and　clay　bricks　(RCP/RBP)　as　construction　and　demolition　wastes　(CDW)　were　evaluated　in　terms　of　their　efficiency,　energy　consumption,　and　cost.　It　was　found　that　replacing　OPC　with　20　%　non-processed　RCP/RBP　led　to　up　to　22　%　loss　of　compressive　strength　of　mortar,　though　the　fluidity　and　flexural　strength　were　similar　to　that　of　the　OPC　mortar.　By　conducting　the　grinding　treatment,　the　RCP/RBP　particles　were　refined;　cement　hydration　was　found　to　be　more　complete　in　the　blended　mortar　meanwhile　the　pore　structure　was　improved.　Calcination　led　to　the　formation　of　new　active　phases　in　RCP/RBP　which　facilitated　the　early-age　cement　hydration　and　contributed　to　more　complete　hydration　at　later　ages.　Test　results　on　mortar　strength　showed　that　the　compressive/flexural　strengths　can　be　enhanced　by　both　treatments　though　the　28-day　compressive　strength　of　RCP　mortar　was　still　11　%　lower　than　that　of　OPC.　The　optimal　grinding　duration　and　calcination　temperature　in　terms　of　enhancing　mortar　strength　was　20　min　and　600　/800　(for　RCP　and　RBP　respectively),　under　which　the　28-day　compressive　strength　of　the　blended　mortars　can　be　enlarged　by　up　to　10.11　%　and　14.33　%,　respectively.　Basically,　calcination　can　enhance　the　mortar　strength　(28　or　90　days)　better　than　grinding　and　the　enhancement　was　more　significant　for　the　RCP　mortar　than　for　the　RBP.　Further　analysis　on　extra　power　consumption　and　cost　performance　suggests　that　the　calcination　treatment　was　more　energy-efficient　and　cost-effective　than　grinding　to　improve　the　mortar　strength　so　it　should　be　a　better　option　to　process　CDW　powder　for　preparing　lower-carbon　cementitious　materials　with　satisfactory　fluidity　and　strength.　©　2023