{"id":65858,"date":"2026-06-20T08:00:31","date_gmt":"2026-06-19T23:00:31","guid":{"rendered":"https:\/\/norimen.net\/?p=65858"},"modified":"2026-06-17T01:18:42","modified_gmt":"2026-06-16T16:18:42","slug":"basics-of-surface-moisture-content-4-states-and-mix-correction","status":"publish","type":"post","link":"https:\/\/norimen.net\/en\/surface-moisture-rate-basics-4-states-mix-correction\/","title":{"rendered":"Basics of Surface Moisture Content | Explaining the Four States of Aggregate Moisture Content and On-Site Mix Design Adjustments"},"content":{"rendered":"

Hello, everyone.<\/p>\n

This is Enta.<\/p>\n

When you\u2019re working on a slope and think, \u201cThe mortar feels unusually runny today,\u201d before you start questioning the mix design,Surface moisture content of sand<\/strong>It's standard practice to be skeptical. (I even doubt the craftsman's water-to-flour ratio, lol.)<\/p>\n

Even if you think you\u2019ve followed the mix ratio listed in the table\u2014\u201cW\/C=50%\u201d\u2014if the sand contains more moisture than expected,<\/p>\n

Since the actual water-to-cement ratio is actually higher, that\u2019s why you end up with super runny mortar lol<\/p>\n

\"Sand<\/p>\n

This time,Basic Knowledge of the Surface Moisture Content of Fine Aggregates<\/strong>I\u2019ll cover everything from the four moisture content states of aggregates to the measurement methods specified by JIS standards and the calculations for on-site mix adjustments\u2014all from a practical, on-site perspective.<\/p>\n

From the same \"Sand Series\"What Is a Chapman Flask?<\/a>\u30fbWhat Does \"1.24 m\u00b3 of Sand for Sprayed Mortar\" Mean?<\/a>If you read this along with the other material, you'll get a complete picture of formulation management.<\/p>\n

The moisture content of aggregates is classified into four levels<\/h2>\n

In civil engineering mix design calculations,Classify the moisture content of aggregates (especially sand) into four categories<\/strong>That's the basic principle.<\/p>\n\n\n\n\n\n\n\n\n
Status<\/th>\nName<\/th>\nDescription<\/th>\n<\/tr>\n<\/thead>\n
\u2460<\/td>\nAbsolutely Dry<\/strong>(Completely Dry)<\/td>\nDried at 105\u00b0C until all moisture is removed. For testing purposes.<\/td>\n<\/tr>\n
\u2461<\/td>\nAir-dried<\/strong><\/td>\nA state in which the substance has been left at room temperature indoors and has reached equilibrium with the air<\/td>\n<\/tr>\n
\u2462<\/td>\nSurface Dry, Saturated<\/strong>(Surface-dried)<\/td>\nThe interior of the granules is filled with water, while only the surface is dry. Basis for formulation calculations<\/td>\n<\/tr>\n
\u2463<\/td>\nMoist<\/strong><\/td>\nThe surface is also wet. This is what the sand at the site usually looks like.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

In the field of mix design calculations, the dry condition shown in Table \u2462 is treated as the \u201creference.\u201d<\/p>\n

The \"apparent dry density,\" which is used to calculate the absolute volume of sand, is also the value obtained by dividing the mass of the sand in its apparent dry state by its apparent dry volume.<\/p>\n

This is specified in JIS A 1109, \u201cTest Methods for Density and Water Absorption of Fine Aggregates.\u201d<\/p>\n

\"Illustration<\/p>\n

What Is Surface Moisture Content?<\/h3>\n

\u300cSurface moisture content<\/strong>\" is based on the surface-dry state,The excess moisture contained in the sand at the job site (in a moist state) compared to the surface-dry condition<\/strong>The percentage.<\/p>\n

In mathematical terms,<\/p>\n

Surface Moisture Content (%) = (Wet Mass \u2013 Surface-Dried Mass) \/ Surface-Dried Mass \u00d7 100<\/strong><\/span><\/p>\n

For example, if you measure 100 g of sand from the site using a Chapman flask and the surface moisture content is 51 TP3T, that means approximately 4.8 g of surface water is adhering to that 100 g of sand.
\n(Strictly speaking, the surface-dry mass is approximately 95.2 g per 100 g of wet mass, and the surface water is approximately 4.8 g)\u2014that\u2019s the general idea.<\/p>\n

How much sand is typically used on a construction site?<\/h3>\n

The sand at the slope construction site had just been delivered from the sand supplier\u2019s plant, andGenerally within the range of 3 to 81 TP3T surface moisture content. Exceeds 101 TP3T first thing in the morning after rain or in uncovered stockyards.<\/strong>That can happen sometimes.<\/p>\n

Conversely, based on our experience in the field, when the air dries out on a midsummer afternoon, the humidity drops to around 1\u201331 TP3T.<\/p>\n

Since it fluctuates throughout the day depending on the season and weather,Measure twice a day\u2014once in the morning and once at noon<\/strong>...is the standard procedure for quality control.<\/p>\n

Generally speaking, covering the area with a blue tarp at all times makes a better impression on the inspector.<\/p>\n

If you measure it every day and gain some experience, you'll come to realize, \"Oh, so this is just how it is,\" lol.<\/p>\n

Two Test Methods in the JIS Standard<\/h2>\n

The method for measuring the surface moisture content of sand is specified in the JIS standardTwo methods are specified in parallel<\/strong>...is being done.<\/p>\n\n\n\n\n\n\n
Specifications<\/th>\nTest Method<\/th>\nEquipment<\/th>\nFeatures<\/th>\n<\/tr>\n<\/thead>\n
JIS A 1111:2015<\/strong><\/td>\nVolume Method \/ Mass Method<\/td>\nChapman flasks, etc.<\/td>\nCan be measured instantly on-site in about 5 minutes<\/td>\n<\/tr>\n
JIS A 1125:2015<\/strong><\/td>\nDry Weight Loss Method<\/td>\nElectronic Balance + Drying Oven<\/td>\nFor Laboratory Use \u00b7 High Precision \u00b7 Time-Consuming<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

\"Chapman<\/p>\n

In the field, the Chapman method specified in JIS A 1111 is the most widely used.<\/h3>\n

At the slope construction site,I want results right away<\/strong>Therefore, the volumetric method using a Chapman flask in accordance with JIS A 1111 is used.<\/p>\n

The test procedure is as follows:<\/p>\n