在過去的20年中，混凝土工業增加了流變儀的使用，以表徵水泥基材料（如漿液，常規混凝土和自密實混凝土）的新鮮流動特性。對定量流變學測量的興趣增加主要是業界希望使用日益複雜的建築材料的結果。商業上可用的流變儀可以從用於測量混凝土的糊狀物組分的台式裝置到用於測量混凝土的容量為20L的大型裝置。傳統上使用已知粘度的標準油進行流變儀校準。然而，混凝土材料是非牛頓稠密懸浮液，並且更準確地表徵為具有屈服應力和塑性粘度的賓漢流體。因此，需要開發具有糊劑，砂漿（小骨料漿）和混凝土（大骨料砂漿）特性的SRM進行校準混凝土流變儀。 NIST開發了兩種Bingham類材料SRM 2492（糊劑）和SRM 2493（砂漿 - 其中包含SRM 2492作為糊劑組分）。目前，正在開發SRM 2497（混凝土 - 將SRM 2493作為砂漿部件）。
糊狀SRM 2492使用平行板流變儀進行認證，並且SRM 2493首次使用電腦模擬而不是物理測量進行認證。使用基於由NIST工程實驗室和信息技術實驗室聯合開發的光滑粒子流體動力學的模型計算SRM 2493流變性質。該模型模擬由非牛頓糊（SRM 2492）與小聚集體（1mm玻璃珠）組成的懸浮液的流動。砂漿SRM 2493的流變特性非常重要，因為沒有物理設備可以測量基本單位的材料的流變特性，並且不受流變儀配置的影響。獲得校準因子後，具有SRM 2493認證值的操作員可以獲得基本單位的流變性能，而不受使用的旋轉流變儀的影響。這些系列的SRMs構成了第一個為1毫米至10毫米顆粒的漿糊和懸浮液設計的流變學參考材料。根據C01.22分委員會（目前正在進行投票）的ASTM測試方法將使用這些SRM來校準流變儀。
SRM2493的一個單元由四個容器組成，一個玻璃瓶的玉米糖漿（500g），兩個塑料瓶的石灰石粉末（每個600g）和一個1mm玻璃珠的塑料罐（1500g）。 SRM 2492與SRM 2493相同，但不包含玻璃珠塑料罐。所提供的材料可以生產至少兩批。準備材料和校準流變儀的說明在證書和網站上提供。
Over the past 20 years, the concrete industry has increased its use of rheometers to characterize the fresh flow properties of cement-based materials (e.g., grouts, conventional concrete, and self-compacting concrete). The increased interest in quantitative rheological measurements has been largely the result of the industry wanting to use increasingly complex construction materials. Commercially available rheometers can vary from table-top devices for measuring the paste component of the concrete, to large units with a capacity of 20 L for measuring concrete. Rheometer calibration is traditionally done using standard oils of known viscosity. Concrete materials, however, are a non-Newtonian dense suspension, and are more accurately characterized as a Bingham fluid, having a yield stress and a plastic viscosity. Thus, there was a need to develop a progression of SRMs having the characteristics of paste, mortar (paste with small aggregates), and concrete (mortar with large aggregates) for calibrating concrete rheometers. NIST has developed two Bingham-like materials SRM 2492 (paste) and SRM 2493 (mortar – which incorporates SRM 2492 as the paste component). Presently, SRM 2497 (concrete – which incorporates SRM 2493 as the mortar component) is being developed.
The paste SRM 2492 was certified using a parallel plate rheometer, and the SRM 2493 was certified using, for the first-time ever, computer simulation instead of physical measurements. The SRM 2493 rheological properties were calculated using a model based on a Smooth Particle Hydrodynamics developed jointly by NIST’s Engineering Laboratory and Information Technology Laboratory. This model simulated the flow of a suspension composed of a non-Newtonian paste (SRM 2492) with small aggregates (1 mm glass beads). Modeling the rheological properties of SRM 2493 was essential because no physical device exists that could measure the rheological properties of the material in fundamental units and with no influence of the rheometer configuration. After obtaining the calibration factors, the operator with the certified values of the SRM 2493 can obtain rheological properties in fundamental units, independent of the rotational rheometer used. These series of SRMs constitute the first rheology reference materials designed for pastes and suspensions with 1 mm to 10 mm particles. An ASTM test method under sub-committee C01.22 (currently under ballot) would use these SRMs for calibration of rheometers.
A unit of SRM 2493 consists of four containers, one glass bottle of corn syrup (500 g), two plastic jars of limestone powder (600 g each) and one plastic jar of 1 mm glass beads (1500 g). SRM 2492 is identical to SRM 2493, but does not contain the plastic jar of glass beads. At least two batches can be produced with the materials provided. Instructions for preparing the material and for calibrating a rheometer are provided on the certificate and on the website.